The prevalence of insomnia and restless legs syndrome among Japanese outpatients with rheumatic disease: A cross-sectional study.

The prevalence of symptomatic insomnia and the prevalence of restless legs syndrome (RLS) are known to be higher among patients with rheumatic diseases compared to the general population. The prevalences of insomnia and RLS reported in a questionnaire by Japanese patients with rheumatic diseases at an outpatient clinic were analyzed herein. The association between the patients' disease activity and their sleep quality was analyzed. Of 121 rheumatic disease patients, 70 were enrolled. The median (interquartile range) age at enrollment was 62.0 (47.8-68.0) years. There were 58 women (82.9%) and 12 men (17.1%), and 43 patients (61.4%) with rheumatoid arthritis (RA), nine (12.9%) with systemic lupus erythematosus (SLE), and 18 (25.7%) with other rheumatic diseases. Twenty patients (28.6%) had one or more moderate-to-severe insomnia symptoms, and 10 (14.3%) were diagnosed with RLS. Among the patients with RA, the swollen joint count based on a 28-joint assessment (SJC28) was significantly higher in the insomnia group (n = 13) compared to the non-insomnia group (n = 30) (p = 0.006). A classification and regression tree (CART) analysis showed that the cut-off points of ≥3 mg/day prednisolone (PSL) treatment and <16.54% as the transferrin saturation (TSAT) value would best predict RLS in rheumatic disease. Patients with rheumatic disease had a high prevalence of symptomatic insomnia and RLS. A higher dose of PSL and lower TSAT were associated with the occurrence of RLS.

Introduction

The rheumatic diseases are a diverse group of chronic diseases characterized by the presence of chronic inflammation affecting structures of the musculoskeletal system, blood vessels, and other tissues. Sleep has a strong regulatory influence on immune functions. The disturbance of the body's immunity caused by sleep deprivation is not limited to the suppression of the response to pathogens; it can also result in the collapse of immunological self-tolerance, which can cause the onset of autoimmune disease [1-3]. Cross-sectional studies have shown that sleep disorders in individuals with autoimmune diseases are correlated with pain, fatigue, psychiatric manifestations, and disease activity [4].

The prevalence of symptomatic insomnia among rheumatic disease patients is as high as 47%–65% [5, 6], and the rates of patients' subjective complaints of deteriorated sleep quality are as high [5, 7–9]. Symptomatic insomnia is frequently associated with disease activity, with general symptoms such as arthralgia, and with various medications. However, insomnia sometimes persists even after an individual's original disease has improved [10]. The presence of insomnia increases the risk of developing rheumatic disease [1], and fragmentation of sleep is associated with exacerbation of the original disease [4, 11, 12].

Restless legs syndrome (RLS) may be present in 20%–30% of individuals' with rheumatic diseases [13-16]. RLS is accompanied by abnormal perception(s) such as an unusual, relaxing, or burning feeling or an impulsive feeling based mainly in the lower limbs. These symptoms become prominent at rest and are relieved by moving. Because RLS is often worse at night, RLS may induce severe insomnia, manifesting as difficulty initiating and maintaining sleep [17]. Although the prevalence of RLS in general populations in East Asian countries including Japan is known to be lower than those in Europe and the U.S. [18], the reported prevalence of RLS among Pakistani patients with rheumatic diseases was rather high at 19.1%.

We conducted the present study to determine the association between the disease activity of rheumatic diseases such as rheumatoid arthritis (RA) during patients' visits to an outpatient clinic and their sleep-related problems. The prevalence of RLS among Japanese outpatients with rheumatic diseases was also investigated.

Patients and methods

Patients

We collected 121 consecutive patients with rheumatic disease treated between August 2017 and May 2018 at the outpatient clinic at Nagasaki University Hospital. The quality of the studies was assessed on the basis of elements from the STROBE checklist for cross-sectional studies [19]. The eligibility criteria for patients participating in this study were: (1) having a clinical diagnosis of RA, systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), systemic sclerosis, vasculitis, osteoarthritis, dermatomyositis, or spondyloarthritis by a rheumatologist; (2) a current user of at least prednisolone or an immunosuppressant according to their medical records; (3) >20 years old, and 4) able to provide informed consent. The exclusion criteria were: (1) the presence of any comorbidity of a medical or psychological/psychiatric condition or treatment revealed by a review of the patient's previous or outside medical records, in the opinion of the Principal Investigator, and (2) being unwilling to participate in a research study or provide research samples or data.

Seventy patients met the initial study criteria and were enrolled in the study (S1 Fig). The STROBE reporting guidelines were used in the design and implementation of our research [19]. The patients' subjective sleep quality, sleep disturbance, severity of insomnia, and daytime sleepiness were evaluated. The patients underwent a screening test for RLS by the questionnaire method described below. Patients who declined to provide informed consent to participate in the study were excluded. Written informed consent was obtained from all individual participants included in the study. The study was reviewed and approved by the Medical Ethical Committee of Nagasaki University Hospital (approval no. 16092619).

Data collection

The patients' demographic and clinical characteristics were collected at the time of the RLS screening (Table 1). The demographic data included each patient's gender, age, body mass index (BMI), drinking habit, smoking habit, comorbidities, past history, and history of regular medication. The patients' laboratory data were obtained, including the white and red blood cell counts, hemoglobin, platelet counts, total protein, albumin, sodium, potassium, chlorine, aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase, blood urea nitrogen, serum creatinine (Cr), estimated glomerular filtration rate (eGFR), serum iron (Fe), unsaturated iron binding capacity, transferrin saturation (TSAT), C-reactive protein (CRP), serum ferritin, blood sedimentation (represented by the erythrocyte sedimentation rate [ESR]), glucose, HbA1c, and urine protein/creatinine ratio (Up/Ucr).

Table 1

The patients' demographic and clinical characteristics.

Age, yrs, median (IQR)	62 (47.8–68)
Female, n (%)	58 (82.9)
Diagnosis, n (%):
RA	43 (61.4)
SLE	9 (12.9)
Mixed connective tissue disease	5 (7.1)
Others	13 (18.6)
Disease duration, yrs, median (IQR)	11 (6–18)
BMI, kg/m2, median (IQR)	21.6 (19.9–24.4)
Smoker, n (%)	10 (14.3)
Sleeping pills, n (%)	10 (14.3)
Oral iron preparation, n (%) *	1 (1.5)
Vitamin D preparations, n (%) *	14 (20.6)
Antipsychotic drugs, n (%) *	1 (1.5)
Laboratory data, median (IQR):
Hemoglobin, g/dl	12.8 (11.6–14.1)
BUN, mg/dl	14.0 (11.0–17.0)
Creatinine, mg/dl	0.69 (0.60–0.80)
eGFR, ml/min/1.73m2	74.3 (58.4–85.2)
Total protein, g/dl	7.50 (7.18–8.82)
Albumin, g/dl	4.15 (3.90–4.43)
Ferritin, ng/ml	55.0 (20.0–99.0)
Iron, μg/dl	77.5 (54.0–118)
UIBC, μg/dl	238 (200–303)
TSAT, %	25.3 (14.6–38.2)
ESR, mm/hr	12.0 (8.00–24.0)
CRP, mg/dl	0.08 (0.03–0.20)
Up/Ucr, g/g▪Cr	0.08 (0.05–0.15)

*A total of 68 patients were evaluated. BMI: body mass index, BUN: blood urea nitrogen, CRP: C-reactive protein, eGFR: estimated glomerular filtration rate, ESR: erythrocyte sedimentation rate, IQR: interquartile range, RA: rheumatoid arthritis, SLE: systemic lupus erythematosus, TSAT: transferrin saturation, UIBC: Unsaturated iron binding capacity, Up/Ucr: urine protein/creatinine ratio.

For the RA patients, the following information was also obtained: the tender joint count based on a 28-joint assessment (i.e., the TJC28), the swollen joint count based on a 28-joint assessment (the SJC28), the Medical Doctors' Global Assessment (MDGA) of RA disease activity on a 100-mm visual analog scale, and the Patient's Global Assessment (PGA) of activity on a 100-mm analog scale. Four clinical activity disease indices, i.e., the Disease Activity Score in 28 joints (DAS28)-CRP, the DAS28-ESR, the Simplified Disease Activity Index (SDAI), and the Clinical Disease Activity Index (CDAI) were calculated as described [20-22].

Questionnaires

We evaluated the patients' sleep quality and disturbance retrospectively over a 1-month period by using the self-reported Japanese version of the Pittsburgh Sleep Quality Index (PSQI) [23]. The 19 questions are categorized into seven components, graded with scores that range from 0 to 3. The PSQI components are as follows: subjective sleep quality (C1), sleep latency (C2), sleep duration (C3), habitual sleep efficiency (C4), sleep disturbances (C5), use of sleeping medication (C6), and daytime dysfunction (C7). The PSQI global score (GS) is evaluated as 0 to 21 points, and a higher score indicates low sleep quality and sleep disturbance. The PSQI cut-off value for poor sleep quality was estimated at ≥6 points.

The severity of the patients' insomnia was assessed by the Japanese version of the Insomnia Severity Index (ISI) [24, 25]. The daytime sleepiness was assessed by the Japanese version of the Epworth Sleepiness Scale (ESS) [26, 27]. The total ISI scores are divided into seven items, each providing a five-point Likert scale (0  =  no problem, 4  =  very severe problem), and the items assess the severity of difficulty initiating sleep (DIS), difficulty maintaining sleep (DMS), and waking up too early (WE). A cut-off score of 10 has been used as the threshold for pathological conditions of insomnia [28]. Responders who had 'mild' to 'very severe' symptoms were defined as having DIS, DMS, and/or WE. Responders who had 'moderate' to 'very severe' symptoms were defined as having moderate to severe DIS, DMS, and/or WE. The insomnia group was defined herein as having at least moderate to severe DIS, DMS, and/or WE. The total ESS score ranges from 0 to 24 points, with higher scores indicating stronger subjective daytime sleepiness. ESS scores of ≥10 points represent increasing levels of 'excessive daytime sleepiness.'

For the screening test for RLS, the Japanese version of the Cambridge-Hopkins questionnaire short-form 13 (CH-RLSq13) was used [29, 30]. The CH-RLSq13 is a self-administered questionnaire with high sensitivity and specificity for the diagnosis of RLS. The questionnaire is comprised of 13 items, 10 of which are related to characteristic symptoms and the exclusion of other conditions (e.g., leg cramping, positional discomfort). The remaining three items are related to the severity and onset of symptoms.

Based on the patients' data obtained from the sleep-related questionnaire, the patients were divided into the poor-sleeper group (with a PSQI global score of ≥6 points) and the nonpoor-sleeper group. The patients were also divided into the severe-insomnia group (with an ISI total score of ≥10 points) and the nonsevere-insomnia group. A third division of patients was made: the excessive daytime sleepiness (EDS) group (with an ESS total score of ≥10 points) and the non-EDS group.

Diagnosis of RLS

After the questionnaire screening was conducted, a board-certified physician of the Japanese Society of Sleep Research (H.K.) interviewed the patients who were suspected of having RLS. These patients were screened by a questionnaire for the five essential diagnostic criteria for RLS as defined by the International Restless Legs Syndrome Study Group (IRLSSG) [17].

Multiplex cytokine/chemokine bead assays

We performed a multiplex analysis of undiluted serum supernatants using the Milliplex MAP Human Cytokine/Chemokine Panel 1 Pre-mixed 38 Plex (Merck Millipore, Darmstadt, Germany) according to the manufacturer's instructions. Within 30 min of their collection, the serum samples were centrifuged at 1500 rpm at 4°C for 5 min, and the liquid phase of the serum was stored at −80°C until use. The levels of the following 41 cytokines/chemokines in the liquid phase of the serum were measured: vascular endothelial growth factor (VEGF), tumor necrosis factor-beta (TNF-β), tumor necrosis factor-alpha (TNF-α), transforming growth factor (TGF)-α, macrophage inflammatory protein (MIP)-1β, MIP-1α, myeloid dendritic cells (MDCs)/ C-C Motif Chemokine Ligand 22 (CCL22), monocyte chemotactic protein (MCP)-3, MCP-1, interferon-gamma (IFN-γ)-induced protein (IP)-10, interleukin (IL)-17, -15, -13, -12 (p70), -12 (p40), -10, -9, -8, -7, -6, -5, -4, -3, -2, -1ra, -1β, and -1α, IFN-γ, IFN-α2, growth-related cytokine (GRO), granulocyte macrophage-colony stimulating factor (GM-CSF), granulocyte-colony stimulating factor (G-CSF), fractalkine, Flt-3 ligand, fibroblast growth factor (FGF)-2, eotaxin, epidermal growth factor (EGF), and sCD40L.

The concentrations were calculated based on the respective standard curve for each cytokine's/chemokine's concentration, assayed in the same manner as the serum samples. The detection limit for each molecule was determined by the recovery of the corresponding standard, and the lowest values with >70% recovery were set as the lower detection limits. All samples were analyzed in duplicate.

Statistical analyses

Categorical variables are presented as counts and percentages. Continuous variables are presented as medians and interquartile ranges (IQR) where non-normally distributed. A nonparametric Wilcoxon rank sum test was used for the inter-group comparisons of multiple variables. Fisher's exact test was also used to test the possible association between each variable factor and the subgroups. Decision tree models for predicting RLS were built with the Classification and Regression Trees (CART) algorithm [31]. The statistical analyses were performed using JMP® Pro14 software (SAS Institute, Cary, NC).

Results

The prevalence and insomnia symptoms in rheumatic disease

The prevalence and severity of insomnia in rheumatic disease were determined: the patients' median score on the PSQI was 6 (IQR 4–9), showing multimodality without normal distribution, and higher scores indicate that the patient's sleep quality is severely disturbed (Fig 1). There were 36 patients (51.4%) who had poor sleep. The number of patients who had DIS, DMS, and WA were 30 (42.9%), 28 (40%), and 20 (28.6%), respectively (Table 2). The number of patients with any insomnia symptoms was 38 (54.3%). Twenty patients (28.6%) had one or more moderate-to-severe insomnia symptoms.

Fig 1

Histogram of the patients' Pittsburgh Sleep Quality Index global scores.

Table 2

The patients' sleep characteristics.

PSQI GS, median (IQR)	6 (4–9)
PSQI GS ≥6	36 (51.4)
ISI, median (IQR)	4 (2–6)
ISI ≥10, n (%)	10 (14.3)
Symptoms of insomnia, n (%)
DIS, mild to very severe	30 (42.9)
DIS, moderate to very severe	13 (18.6)
DMS, mild to very severe	28 (40.0)
DMS, moderate to very severe	12 (17.1)
WA, mild to very severe	20 (28.6)
WA, moderate to very severe	1 (1.4)
Any symptoms	38 (54.3)
Any moderate to severe symptoms	20 (28.6)
ESS, median (IQR)	5 (3–8)
ESS ≥10, n (%)	13 (18.6)
RLS, n (%)	10 (14.3)

DIS: difficulty initiating sleep, DMS: difficulty maintaining sleep, ESS: Epworth Sleepiness Scale, ISI: Insomnia Severity Index, PSQI GS: Pittsburgh Sleep Quality Index global score, RLS: restless legs syndrome, WA: wake up too early.

Comparison of the RA patients' disease activity scores between insomnia group and non- insomnia group

In the group of 43 RA patients, the disease activity scores were compared between the patients with and without any moderate-to-severe insomnia symptoms: the SJC28 was significantly higher in the insomnia group (n = 13) compared to the non-insomnia group (n = 30) (p = 0.006) (S1 Table).

The prevalence of RLS and its disease-related features in rheumatic disease

Ten patients (14.3%) with rheumatic disease were diagnosed with RLS, including five RA patients, two SLE patients, and one patient with MCTD. The median age (minimum–maximum) at RLS onset was 40 (15–60) years. Five of the 10 patients with RLS developed RLS after the diagnosis of rheumatic disease: in three of these five patients, the RLS and rheumatic disease had developed at almost the same time; in one patient, the RLS had developed before the diagnosis of rheumatic disease; in the remaining patient, the onset of RLS was not known. Nine patients reported experiencing RLS symptoms <2 days/week during the prior 12 months, and only one patient reported experiencing RLS symptoms 4–5 days/week.

We divided the total series of 70 patients into two groups based on whether they had RLS or not (Table 3). Among the disease-related features at baseline, younger age (p = 0.02), higher PSL dose (p = 0.002), lower total protein (p = 0.02), lower serum level of iron (p = 0.03) and lower TSAT (p = 0.03) were significantly related to RLS.

Table 3

Comparisons of demographic and clinical characteristics between RLS group and non-RLS group.

	RLS (n = 10)	Non-RLS (n = 60)	p-value
Age, yrs, median (IQR)	47.5 (36.0–64.0)	62.5 (49.3–71.0)	0.02
Female, n (%)	8 (80.0)	50 (83.3)	0.80
Diagnosis, n (%)
RA	5 (50.0)	38 (63.3)	0.42
SLE	2 (20.0)	7 (11.7)	0.61
Disease duration, yrs, median (IQR)	15 (7.5–23)	10 (5–18)	0.25
BMI, kg/m2, median (IQR)	21.2 (19.0–27.9)	21.9 (19.9–24.3)	0.87
Smoker, n (%)	9 (90.0)	51 (85.0)	0.68
Sleeping pills, n (%)	2 (20)	8 (13.3)	0.63
Vitamin D preparations, n (%) *	3 (30)	11 (19.0)	0.42
Prednisolone (mg)	6.00 (3.75–8.25)	0.50 (0.00–0.50)	0.002
Prednisolone ≥ 3 mg (%)	9 (90.0)	20 (33.3)	0.001
Laboratory data, median (IQR):
Hemoglobin, g/dl	12.8 (11.7–13.9)	12.7 (11.6–14.15)	0.78
BUN, mg/dl	12.0 (7.0–20.0)	14.0 (12.0–17.0)	0.28
Creatinine, mg/dl	0.63 (0.53–0.83)	0.7 (0.6–0.8)	0.30
eGFR, ml/min/1.73m2	82.0 (74.3–97.5)	72.4 (58.0–95.3)	0.06
Total protein, g/dl	7.2 (7.1–7.4)	7.6 (7.2–7.9)	0.02
Albumin, g/dl	4.05 (3.8–4.325)	4.2 (4.0–4.5)	0.17
Ferritin, ng/ml	23.5 (14.0–64.5)	55.0 (24.5–104)	0.06
Iron, μg/dl	54.0 (35.0–82.0)	84.5 (56.3–128)	0.03
Unsaturated iron binding capacity, μg/dl	292 (261–329)	226 (197–294)	0.10
TSAT, %	14.7 (10.6–25.8)	26.5 (17.0–39.0)	0.03
ESR, mm/hr	10.0 (7.5–27.3)	12.0 (8.0–24.0)	0.92
CRP, mg/dl	0.16 (0.03–0.60)	0.08 (0.03–0.19)	0.48
Up/Ucr, g/g▪ Cr	0.04 (0.06–0.13)	0.08 (0.05–0.17)	0.25

BMI: body mass index, BUN: blood urea nitrogen, CRP: C-reactive protein, eGFR: estimated glomerular filtration rate, ESR: erythrocyte sedimentation rate, IQR: interquartile range, RA: rheumatoid arthritis, SLE: systemic lupus erythematosus, TSAT: transferrin saturation, Up/Ucr: urine protein/creatinine ratio. P-values were determined by nonparametric Wilcoxon rank sum test and Fisher's exact test.

Comparison of the patients' backgrounds evaluated with the PSQI, ISI, and ESS in the RLS and non-RLS groups

The patients' backgrounds evaluated with the PSQI, ISI, and ESS were compared between the RLS group and the non-RLS group (Table 4). Eight of the 10 patients (80%) in the RLS group and 19 of the 60 patients (32%) in the non-RLS group reported getting <6 hr of sleep per night, revealing a significant between-group difference (p = 0.004). There was no significant difference regarding difficulty sleeping in seven of the RLS patients (70%) compared to 23 of the non-RLS patients (38%) (p = 0.06). There was no significant between-group difference in daytime sleepiness assessed by the ESS.

Table 4

Comparisons of sleep characteristics between the RLS and non-RLS groups.

	RLS (n = 10)	Non-RLS (n = 60)	p-value
PSQI
Global score, median (IQR)	8.0 (4.0–14.0)	5.5 (4.0–9.0)	0.16
Global score ≥6, n (%)	6 (60)	30 (50)	0.56
PSQI components, n (%)
C1: subjective sleep quality ≥2	3 (30)	14 (23)	0.64
C2: sleep latency ≥2*	4 (40)	15 (25)	0.32
C3: sleep duration ≥2**	8 (80)	19 (32)	0.004
C4: habitual sleep efficiency ≥2***	1 (10)	4 (6.7)	0.71
C5: sleep disturbances ≥2	7 (70)	37 (62)	0.61
C6: use of sleeping medication ≥2****	2 (20)	12 (20)	1.00
C7: daytime dysfunction ≥2	1 (10)	3 (5.0)	0.53
ISS, median (IQR)	5.5(3.0–8.5)	4.0 (2.0–6.0)	0.25
ISS ≥10, n (%)	2 (20.0)	8 (13.3)	0.63
Symptoms of insomnia, n (%)
Difficulty initiating sleep	7 (70)	23 (38)	0.06
Difficulty maintaining sleep	4 (40)	24 (40)	1.00
Waking up too early	1 (10)	19 (31)	0.16
Any symptoms, mild to very severe	7 (70)	31 (52)	0.28
ESS, median (IQR)	5.0 (3.25–7.75)	5.0 (3.00–8.75)	0.93
ESS ≥10, n (%)	2 (20.0)	11 (18.3)	1.00

*Sleep latency ≥31 min and the presence of difficulty initiating sleep.

**Total sleep time <6 hr.

***Sleep efficiency <85%.

**** >1 time. P-values were determined by nonparametric Wilcoxon rank sum test and Fisher's exact test. ESS: Epworth Sleepiness Scale, ISS: Insomnia Severity Index, PSQI: Pittsburgh Sleep Quality Index.

Assessment of the cut-off values of the predictors of RLS in the rheumatic disease patients

The predicting factors associated with RLS in the rheumatic disease patients as revealed by the CART analysis were examined, with the explanatory variables of age at onset, the daily PSL dose, and the TP, Fe, and TSAT levels (which showed significant differences in a univariate analysis) for the CART analysis. In the decision tree analysis, the calculated minimum number of cases of the child node after the analysis was 10, and the analysis was terminated before the number of cases of the child node became <10. The cut-off point of ≥3 mg/day for the PSL dose and <16.54% for TSAT provided the best performance for predicting RLS in rheumatic disease (Fig 2).

Fig 2

Classification and regression trees (CART) for predicting factors associated with RLS.

Discussion

This study provides the first report of the prevalence of RLS among individuals with rheumatic diseases in Japan. The association between RLS and higher PSL dose in rheumatic diseases has not been discussed, and it is necessary to clarify the significance of this association in pathophysiology; a verification of our findings in further prospective studies of larger multicenter populations is also needed.

The prevalence of RLS among our present patients with rheumatic diseases was significantly higher than that reported in the general populations of Asian countries [18]. The reported prevalence of RLS in the Japanese general population is 1.8% [32]. The reported prevalence of RLS was 27.7% among RA patients in Canada [14], 15.3% among patients with Sjögren's syndrome in Sweden [33], 30.6%–37.5% among subjects with SLE in Turkey and Canada [15, 34], and 19.1% among patients with rheumatic diseases in Pakistan [16]. Compared to previous reports, the prevalence of RLS in our study (14.3%) was similar to that in other countries.

Our study subjects were outpatients with relatively stable conditions. There have been no reports of RLS coexistence in the early stages of or in conditions with high disease activity. Interestingly, half of our patients with RLS developed RLS after the diagnosis of rheumatic disease; in three of these five patients, the RLS and rheumatic disease had developed almost simultaneously; in one patient, the RLS developed before the diagnosis of rheumatic disease, and in the remaining patient, the onset of RLS was unknown. It is necessary to determine whether RLS develops secondarily to rheumatic disease, and to further clarify the association between the disease activity of rheumatic disease and RLS.

It is not yet known whether PSL treatment affects the disease development of RLS in rheumatic disease. Only a single case report showed that oral PSL was effective in a patient with RLS who was resistant to other therapies [35]. However, other reports described an association between PSL treatment and sleep disorder [2, 36]. In our present investigation, the serum levels of GRO (p = 0.01), IL-8 (p = 0.003), and IL-1ra (p = 0.03) measured by multiplex cytokine/chemokine bead assays (S2 Table) were significantly higher in the group with the PSL cut-off point of ≥3 mg/day compared to the PSL <3 mg/day group, suggesting potential roles of inflammation and immunological alteration in the mechanisms of action in RLS [37].

The distances between each pair of cytokines were also analyzed, based on the Spearman's correlation coefficients of the PSL cut-off point ≥3 mg/day; the results are shown as a heatmap (S2 Fig). The correlations of pairs of cytokines/chemokines/growth factors showed different patterns between the PSL ≥3 mg/day group and the PSL <3 mg/day group. The cytokines/chemokines/growth factors including pro-inflammatory cytokines (IL-2, IL-6, IL-15, IFN-γ) were generally lower and correlated with an anti-inflammatory cytokine (IL-1ra) with PSL <3 mg/day group compared to the PSL ≥3 mg/day group. This result may indicate that an anti-inflammatory cytokine might exert control in the PSL <3 mg/day group as a host defense mechanism. Accordingly, our PSL ≥3 mg/day and <3 mg/day groups differed with elevated downstream levels of pro-inflammatory cytokines/chemokines/growth factors, and these variations may have affected the disease activity and mechanism of RLS.

Iron deficiency is associated with RLS pathogenesis, and iron replacement therapy is generally widely used as a treatment for RLS when the patient's level of TSAT, a marker of iron availability, is low [38]. In the present study, the TSAT level was significantly lower in the RLS group (p = 0.03). These data suggest that when iron deficiency is present in a patient with a rheumatic disease, iron replacement therapy is effective. However, under chronic inflammation, increased iron trapping within the macrophages and hepatocytes results in a higher level of ferritin [39, 40], and clinicians should be aware that the administered iron may not be effective for erythropoiesis.

The age of the present RLS group was significantly lower than that of the non-RLS group (p = 0.02). In this study, five of the 10 patients in the RLS group developed RLS before the age of 45 years. It was reported that early-onset RLS (occurring before the age of 45 years) has a high incidence of family history [41, 42]. In the present examination, one or more genetic factors may be involved with the earlier onset of RLS; however, our patients' family histories of RLS were not investigated sufficiently.

RLS often results in a higher prevalence of DIS and DMS compared to subjects without RLS [17]. In our study, the quality of sleep tended to be worse in the RLS group, but it was not clearly related to insomnia. This may be due to the fact that seven of the 10 RLS patients did not experience the symptoms of insomnia every day. In addition, only one RLS patient felt moderately distressed, although the patient was aware of RLS symptoms ≥4 days/week. We speculate that insomnia and RLS had a poor correlation in our study population in part because the severity of RLS was mild.

Vitamin D deficiency has been reported to be associated with RLS, and vitamin D replacement therapy has been effective in reducing the symptoms of RLS patients who had vitamin D deficiency [43-46]. In the present study, 20.6% of the enrolled patients were administered vitamin D, and this therapy may have obscured symptoms of RLS. It is necessary to make an adjustment that includes vitamin D deficiency and replacement therapy.

It was reported that insomnia could be attributed to RA in up to 42% of cases, linking sleep disturbance to pain, mood, and disease activity [47]. Our present findings also showed that the disease activity component of RA was higher in the insomnia group compared to the non-insomnia group. The results of our analyses indicated that insomnia is a consequence of joint pain in patients with RA, and chronic joint pain may result in a vicious cycle in which sleep disturbance activates clinical symptoms of pain, which then contribute to further sleep loss.

The limitations of our study deserve some discussion. First, the study population consisted of a small number of outpatients (n = 70) treated at a single center, with no a-priori statistical power analysis. This was an exploratory study, and we did not determine the number of samples required at the start of the study because the prevalence of RLS in Japanese rheumatic diseases is unknown. Second, there was a potential source of bias at the baseline including confounding (per the STROBE checklist). Because the number of RLS patients in this study was small and a multivariate analysis could not be performed, the adjustment for confounding factors was insufficient. In addition, patients with various rheumatic diseases such as RA and SLE were included in this study, and thus the patients' background characteristics such as being at a susceptible age for a disease and the amount of PSL and concomitant immunosuppressants varied depending on the rheumatic disease. The study population was thus not homogeneous with respect to the patients' backgrounds and treatments, which are likely to affect insomnia and RLS. Additional similar investigations based on each rheumatic disease would be informative.

Third, patients with high disease activity could not be included because this study was of outpatients with stable symptoms, and thus patients with relatively mild symptoms of insomnia and RLS might have participated. However, all of the data are presented in order to avoid selective reporting. In this study, an analysis was performed based on a hypothesis, and there is no evidence of data dredging. Further prospective studies of larger multicenter populations are required to clarify and sufficiently adjust the analyses for RLS and related factors in rheumatoid diseases, including confounding factors.

Conclusions

This is the first report of the prevalence of insomnia and RLS in Japanese patients with rheumatic diseases. The prevalence of RLS in this series of patients with rheumatic diseases was 14.3%, and we consider this value as simply exploratory due to the limitations of the study. The cut-off point of ≥3 mg/day for the PSL dose and <16.54% for TSAT were observed to provide the best performance for predicting RLS in rheumatic disease. The serum levels of GRO, IL-8, and IL-1ra were significantly higher in the group with the PSL cut-off point of ≥3 mg/day compared to the PSL <3 mg/day group, suggesting potential roles of inflammation and immunological alteration in the mechanisms of action in RLS. The relationships among rheumatic disease activity with an imbalance of cytokines/chemokines, RLS, and insomnia should be clarified in large multicenter populations.

Patient enrollment flow chart.

(TIF)

Click here for additional data file.

Heat-maps of nearest-neighbor correlations of cytokines in the PSL cut-off point ≥3 mg/day and <3 mg/day.

For each cytokine analyzed, the distance between the PSL ≥3 mg/day group and the PSL <3 mg/day group was determined based on Spearman's correlation coefficient.

(TIF)

Click here for additional data file.

Insomnia and disease activity scores in the studied RA patients.

(DOCX)

Click here for additional data file.

Cytokine profile of patients treated with prednisolone (PSL) ≥3 mg/day and those treated with <3 mg/day.

(DOCX)

Click here for additional data file.

(XLSX)

Click here for additional data file.

23 Dec 2019

PONE-D-19-29396

The prevalence of insomnia and restless legs syndrome among Japanese outpatients with rheumatic disease: A cross-sectional study

PLOS ONE

Dear Dr. Ichinose,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

In particular, your manuscript was assessed by four reviewers, all experts in sleep and RLS research. I encourage you to revise your manuscript taking account of all the comments made by each reviewer. Please, pay particular attention to highlight the limitations of your manuscript mentioned by reviewers 2 and 3.

In addition, please take account of the following:

- paragraph on patients, page 5-6. Please, specify the "initial study criteria", and in particular the eligibility criteria and the sources and methods of selection of participants, according to the STROBE checklist. Were the patients consecutive?

- please, present differences with P >= 0.05 as non-significant, rather than as trends or tendencies. Please, provide a reference for the Classification and Regression Trees (CART) algorithm. Please, avoid making unsupported inferences about the significance of differences between your study sample and the general population (in this respect, cf. also the comment by reviewer 3 on the lack of a control group in your study).

- In the Discussion section, please describe your efforts to address potential sources of bias, as per the STROBE checklist, addressing in particular confounding variables, lack of generalizability, selective reporting, post hoc analyses, and data dredging. In the paragraph on limitations (page 18), please clarify or correct the sentence "We examined a small number of outpatients (n=41) treated at a single center".

- Please, cite and discuss the following reference: Mod Rheumatol. 2013 Jul;23(4):705-8. doi: 10.1007/s10165-012-0714-x. Epub 2012 Jul 14, which is related to RLS and rheumatic diseases in Asia.

- The last paragraph of the Discussion (page 19) needs be rewritten. The sentence "The patients ... were associated with RLS" is written incorrectly. The following sentence would have been valid even irrespective of  the present manuscript, and would thus seem to support the third reviewer's concern that this manuscript is not characterized by a sufficient level of novelty for the advancement of our knowledge in this field. Please, elaborate and clarify.

- Please, increase the resolution of supplementary figure 2.

- PLOS journals require authors to make all data necessary to replicate their study’s findings publicly available without restriction at the time of publication (cf. https://journals.plos.org/plosone/s/data-availability). You are therefore required to submit the values behind the median and interquartile ranges and other measures reported and the values used to build graphs, either in a public repository (recommended) or as supplementary files.

We would appreciate receiving your revised manuscript by Feb 04 2020 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter.

To enhance the reproducibility of your results, we recommend that if applicable you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). This letter should be uploaded as separate file and labeled 'Response to Reviewers'.

A marked-up copy of your manuscript that highlights changes made to the original version. This file should be uploaded as separate file and labeled 'Revised Manuscript with Track Changes'.

An unmarked version of your revised paper without tracked changes. This file should be uploaded as separate file and labeled 'Manuscript'.

Please note while forming your response, if your article is accepted, you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out.

We look forward to receiving your revised manuscript.

Kind regards,

Alessandro Silvani, M.D., Ph.D.

Academic Editor

PLOS ONE

Journal Requirements:

When submitting your revision, we need you to address these additional requirements:

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at http://www.plosone.org/attachments/PLOSOne_formatting_sample_main_body.pdf and http://www.plosone.org/attachments/PLOSOne_formatting_sample_title_authors_affiliations.pdf

2. Please provide additional details regarding participant consent to collect demographic data, clinical data and serum samples. In the ethics statement in the Methods and online submission information, please ensure that you have specified (1) whether consent was informed and (2) what type you obtained (for instance, written or verbal, and if verbal, how it was documented and witnessed). If your study included minors, state whether you obtained consent from parents or guardians. If the need for consent was waived, please ensure that you have discussed whether all data were fully anonymized before you accessed them and/or whether the IRB or ethics committee waived the requirement for informed consent.

3. We noticed minor instances of text overlap with the following previous publication(s), which need to be addressed:

https://www.sciencedirect.com/science/article/abs/pii/S1521661618304297?via%3Dihub

The text that needs to be addressed involves the last paragraph of the Discussion section.

In your revision please ensure you cite all your sources (including your own works), and quote or rephrase any duplicated text outside the methods section. Further consideration is dependent on these concerns being addressed.

4. Please include additional information regarding the survey or questionnaire used in the study and ensure that you have provided sufficient details that others could replicate the analyses. For instance, if you developed a questionnaire as part of this study and it is not under a copyright more restrictive than CC-BY, please include a copy, in both the original language and English, as Supporting Information.

5. In your Methods section, please provide additional information about the participant recruitment method and the demographic details of your participants.

Please ensure you have provided sufficient details to replicate the analyses such as:

a) the recruitment date range (month and year),

b) a description of how participants were recruited, and

c) descriptions of where participants were recruited and where the research took place.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Partly

Reviewer #3: Yes

Reviewer #4: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: I Don't Know

Reviewer #3: Yes

Reviewer #4: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: No

Reviewer #4: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: In the present study the authors intend to determine the association between patients'

disease activity of rheumatoid arthritis (RA) during their outpatient visits and their sleep-related problems. They investigated the prevalence of RLS among Japanese outpatients (121) with rheumatic diseases.

This was a cross-sectional survey without intervention of 70 patients with

rheumatic disease among 121 eligible outpatients.

Patients' subjective sleep quality, sleep disturbance, severity of insomnia, and daytime sleepiness has been evaluated and a screening test for RLS performed by questionnaire.

Comments:

Inclusion and exclusion criteria should be detailed.

STROBE guidelines must be explained or related to a citation.

The authors correctly approached the queries by an adequate analysis of both scores and laboratory data although the sample size is quite small to generalize the results.

The authors did a good examination of the literature and clearly displayed limits of the study.

the study is well written and contextualized, but not particularly original in the hypothesis and therefore in the conclusions.

in fact, these are clinic-lab data observations that confirm the general literature data applied to rheumatoid arthritis

Reviewer #2: This study by Kayoko Urashima et al, assessed the frequency of insomnia and restless legs syndrome (RLS) in consecutive outpatients with rheumatic diseases (RD). Although the small sample of patients enrolled, this study could be of interest, as insomnia and RLS are both prevalent in patients with RD.

Here are major concerns:

1- The definition of insomnia (primary endpoint of this study) is not clear. Did patients had face to face interview? Was ICSD-3 or DSM-5 criteria used for the diagnostic of insomnia?

2- In the method section, authors defines clinically severe insomnia with threshold of insomnia severity index (ISI) above 10/28, instead of >14/28, the validated cut-off for moderate insomnia, and the cutoff of 22/28 for severe insomnia. Can authors justify why they used different ISI cutoff for this study?

3- The international RLS study group rating scale (IRLSQ) is worldwide used to assess RLS severity. Did authors assess severity with IRLSQ? If not available, is there any data on RLS severity assessment (Clinical global impression)?

Here are minor concerns:

1- In the introduction, it’s stated that sleep deprivation can cause the onset of autoimmune diseases, however, the study cited is on animal model, can authors provide other clincial studies ?

2- The presence of RLS was well done, as RLS was screened with questionnaire, and the diagnostic confirmed by physician, in this population with chronic pain complain, a condition that can mimic RLS symptoms. Can authors provide how many patients met the five essential criteria, and how many have RLS Diagnostic?

3- What was the age at RLS onset and age at daily RLS symptoms? Some patients didn’t had daily RLS symptoms, can authors provide the frequency of RLS for each patients? Did authors considered patients with less than 3 time a week of RLS symptom as sufferer?

4- In case of ferritin below 75µg/l, RLS is considered as secondary to iron depletion. Can authors provide how many patients with RLS were below this cutoff ? is there any difference between RLS and no-RLS patients ?

4- Patients with comorbid RLS and RD were younger than those without RLS. However, RLS frequency increase with age in the general population. How authors explain such result?

5- In the discussion section, there is mistake : “Interestingly, five of the 10 patients in the present RLS group had developed RLS after the diagnosis of rheumatic disease: one patient had developed RLS during almost the same period, and three patients developed rheumatic disease before the onset of RLS (the time course of the fifth RLS patient was unknown).”

How many patients have RLS before RD diagnostic, and how many after ?

6- In the discussion section, this sentence is not clear: “The correlation of pairs of cytokines/chemokines/growth factors showed different patterns between the PSL ≥3 mg/day group and the PSL <3 mg/day group. The correlation of pro- and anti-inflammatory cytokines in serum varied between the PSL ≥3 mg/day and <3 mg/day groups, and these variations may have affected the disease activity and mechanism of RLS.”

Please, can authors explain with more details what is the clinical implication of such finding?

Reviewer #3: While the study has been carried out with sufficient accuracy and especially the doagnosis of RLS was made following appropriate procedures and criteria, this stdy suffers of some problems:

1) The sample size is quite small for a study of this nature:

2) The authors should have included a control group randomly selected from the general population of the same geographical region;

3) The English form needs improvement.

Finally, I doubt that describing an already well.know association (RLS and rheumatic disease) in a different population, together with the problems expressed above, can represent a sufficient level of novelty for the advancement of our knowledge in this field.

Reviewer #4: This is a very interesting cross sectional study assessing the prevalence of RLS and sleep disorders in patients with RA exploring various potential contributing factors.

This is a well designed study with vigorous methodology.

The statistical analysis is sophisticated and appropriate.

Major issue:

the paper is written in a form of English that even though are grammatically correct, do not match a scientific way of writing (e.g. we also analyzed, we next compared, etc)

The discussion is very descriptive with no information regarding potential mechanisms and physiological explanations.

Authors need to critically review their data suggesting potential mechanisms of causes

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

Reviewer #4: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step.

14 Jan 2020

Please see the response to reviewers file.

Submitted filename: Response to reviewers_FINAL VERSION.docx

Click here for additional data file.

4 Feb 2020

PONE-D-19-29396R1

The prevalence of insomnia and restless legs syndrome among Japanese outpatients with rheumatic disease: A cross-sectional study

PLOS ONE

Dear Dr. Ichinose,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

The manuscript improved as a result of the revision. However, the following issues have not been sufficiently addressed:

- 1. Consecutive enrollment should be mentioned in the manucript text and not only in the rebuttal.

- 2. The meaning of the sentence " There was also a lack of generalizability, because all of the rheumatic

diseases were included for the analyses, and it is difficult to generalize in regard to disease

backgrounds and treatments associated with insomnia and RLS" is unclear. Generalizability from the STROBE checklist perspective refers to external validity. How does this relate to "generalize in regard to disease

backgrounds and treatments associated with insomnia and RLS"?

- 3. The meaning of the sentence "In addition, the total sample size at the start of the study was not determined, because the significance of what our findings revealed related to our outcome measurement (efficacy of the protocol or proposed technique) and the comparisons thereof is exploratory and not confirmative" is even less clear. Please, reword, and make specific reference to statistical power analysis.

- 4. In the conclusions, please make it explicit that the results mentioned from line 388 onwards are to be considered as exploratory due to the limitations of the study.

We would appreciate receiving your revised manuscript by Mar 20 2020 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter.

To enhance the reproducibility of your results, we recommend that if applicable you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). This letter should be uploaded as separate file and labeled 'Response to Reviewers'.

A marked-up copy of your manuscript that highlights changes made to the original version. This file should be uploaded as separate file and labeled 'Revised Manuscript with Track Changes'.

An unmarked version of your revised paper without tracked changes. This file should be uploaded as separate file and labeled 'Manuscript'.

Please note while forming your response, if your article is accepted, you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out.

We look forward to receiving your revised manuscript.

Kind regards,

Alessandro Silvani, M.D., Ph.D.

Academic Editor

PLOS ONE

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

Reviewer #3: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: (No Response)

Reviewer #2: Yes

Reviewer #3: No

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: (No Response)

Reviewer #2: I Don't Know

Reviewer #3: I Don't Know

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: (No Response)

Reviewer #2: Yes

Reviewer #3: No

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: (No Response)

Reviewer #2: Yes

Reviewer #3: No

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: (No Response)

Reviewer #2: (No Response)

Reviewer #3: The authors have made little significant changes to their manuscript and my previous concerns have not been addressed adequately.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: Yes: Monica Puligheddu

Reviewer #2: No

Reviewer #3: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step.

21 Feb 2020

Please see the attached file.

Submitted filename: Response to reviewers_R1_022120_FINAL VERSION.docx

Click here for additional data file.

24 Feb 2020

PONE-D-19-29396R2

The prevalence of insomnia and restless legs syndrome among Japanese outpatients with rheumatic disease: A cross-sectional study

PLOS ONE

Dear Dr. Ichinose,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

In particular, the text at line 69 ("We collected the consecutive data of 121 patients...") is unclear. Does the adjective "consecutive" refer to the data or to the patients? This has implications (cf, eg, paper PMID 23846607). Please, reword and clarify.

Moreover, the revised text at lines 189-191 and 342-347 appears statistically inconsequent (cf, eg, papers PMID 11560206 and https://doi.org/10.1080/19312450701641375). I suggest that you delete this text and simply modify the text at lines 341-342 as follows: "The limitations of our study deserve some discussion. First, the study population consisted of a small number of outpatients (n=70) treated at a single center, with no a-priori statistical power analysis."

We would appreciate receiving your revised manuscript by Apr 09 2020 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter.

To enhance the reproducibility of your results, we recommend that if applicable you deposit your laboratory protocols in protocols.io, where a protocol can be assigned its own identifier (DOI) such that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). This letter should be uploaded as separate file and labeled 'Response to Reviewers'.

A marked-up copy of your manuscript that highlights changes made to the original version. This file should be uploaded as separate file and labeled 'Revised Manuscript with Track Changes'.

An unmarked version of your revised paper without tracked changes. This file should be uploaded as separate file and labeled 'Manuscript'.

Please note while forming your response, if your article is accepted, you may have the opportunity to make the peer review history publicly available. The record will include editor decision letters (with reviews) and your responses to reviewer comments. If eligible, we will contact you to opt in or out.

We look forward to receiving your revised manuscript.

Kind regards,

Alessandro Silvani, M.D., Ph.D.

Academic Editor

PLOS ONE

[Note: HTML markup is below. Please do not edit.]

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step.

25 Feb 2020

Please see the attached file.

Submitted filename: Response to reviewers_R2_022520_FINAL VERSION.docx

Click here for additional data file.

26 Feb 2020

The prevalence of insomnia and restless legs syndrome among Japanese outpatients with rheumatic disease: A cross-sectional study

PONE-D-19-29396R3

Dear Dr. Ichinose,

We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements.

Within one week, you will receive an e-mail containing information on the amendments required prior to publication. When all required modifications have been addressed, you will receive a formal acceptance letter and your manuscript will proceed to our production department and be scheduled for publication.

Shortly after the formal acceptance letter is sent, an invoice for payment will follow. To ensure an efficient production and billing process, please log into Editorial Manager at https://www.editorialmanager.com/pone/, click the "Update My Information" link at the top of the page, and update your user information. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, you must inform our press team as soon as possible and no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

With kind regards,

Alessandro Silvani, M.D., Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

2 Mar 2020

PONE-D-19-29396R3

The prevalence of insomnia and restless legs syndrome among Japanese outpatients with rheumatic disease: A cross-sectional study

Dear Dr. Ichinose:

I am pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please notify them about your upcoming paper at this point, to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

For any other questions or concerns, please email plosone@plos.org.

Thank you for submitting your work to PLOS ONE.

With kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Prof. Alessandro Silvani

Academic Editor

PLOS ONE