Chinese Systemic Lupus Erythematosus Treatment and Research Group Registry IX: Clinical Features and Survival of Childhood-Onset Systemic Lupus Erythematosus in China.

BACKGROUND: Approximately 15-20% cases of systemic lupus erythematosus (SLE) are diagnosed in children. There have been a few studies reporting the epidemiological data of pediatric-onset SLE (cSLE) in China, neither comparing the differences between cSLE and adult-onset SLE (aSLE). The aim of this study was to describe the impact of age of onset on clinical features and survival in cSLE patients in China based on the Chinese SLE Treatment and Research group (CSTAR) database.
METHODS: We made a prospective study of 225 cSLE patients (aged
Results: The mean age of cSLE patients was 12.16 ± 2.92 years, with 187 (83.1%) females. Fever (P < 0.001) as well as mucocutaneous (P < 0.001) and renal (P = 0.006) disorders were found to be significantly more frequent in cSLE patients as initial symptoms, while muscle and joint lesions were significantly less common compared to aSLE subjects (P < 0.001). The cSLE patients were found to present more frequently with malar rash (P = 0.001; odds ratio [OR], 0.624; 95% confidence interval [CI], 0.470-0.829) but less frequently with arthritis (P < 0.001; OR, 2.013; 95% CI, 1.512-2.679) and serositis (P = 0.030; OR, 1.629; 95% CI, 1.053-2.520). There was no significant difference in SLE disease activity index scores between cSLE and aSLE groups (P = 0.478). Cox regression indicated that childhood onset was the risk factor for organ damage in lupus patients (hazard ratio 0.335 [0.170-0.658], P = 0.001). The survival curves between the cSLE and aSLE groups had no significant difference as determined by the log-rank test (0.557, P = 0.455).
CONCLUSIONS: cSLE in China has different clinical features and more inflammation than aSLE patients. Damage may be less in children and there is no difference in 5- year survival between cSLE and aSLE groups.

Introduction

Systemic lupus erythematosus (SLE) is an autoimmune disease with a broad range of clinical and serological diversity. Although the peak age of onset occurs in middle younger (16–50 years), approximately 15–20% patients are children or adolescents under the age of 16 years.[1] The diagnosis of childhood-onset SLE (cSLE) ranged from 14 to 20 years was defined as 16 years old in the most studies.[23]

According to the previous studies, cSLE presents vary in disease profile.[34567] The cSLE patients have more frequent involvement in renal, hematological system and central nervous system, as well as less pulmonary involvement and arthritis, compared with adult-onset SLE (aSLE) patients.[289] With different evaluation method, the comparison of disease activity between early- and late-onset SLE is not certain.[1011] However, cSLE patients are more likely to receive intensive drug therapies and have a two-fold higher mortality rate.[101112]

The demographic, clinical, and laboratory features of cSLE are variable in different ethnic groups.[1413141516] Meanwhile, the data of Chinese lupus were limited due to lack of prospective multicenter studies.[7] Chinese SLE Treatment and Research group (CSTAR) developed the first nationwide online registry of Chinese lupus. Based on the CSTAR cohort, we analyzed differences of childhood-onset and adult-onset lupus patients in disease profiles, including clinical manifestation and outcomes.

Methods

Ethical approval

This study was approved by the Institutional Review Board of Peking Union Medical College Hospital (Beijing, China), which was the lead research site. All patients had signed informed consent themselves or through their legal guardians before being registered.

Patient recruitment

Our prospective study was based on the CSTAR online registry, which includes patients from 104 high-ranked rheumatology centers, covering 30 provinces in China. Patients were included only if they fulfilled the 1997 revised American College of Rheumatology (ACR) criteria. This online registry was launched in April 2009, and 2104 Chinese SLE patients were registered until February 2010. For this study, we focused on cSLE patients who were under 16 years of age of onset and compared them with aSLE patients whose age of onset was between 16 and 50 years.

Data collection

All CSTAR centers provided uniform evaluations and recorded data with the same protocol-directed methods. Demographic data were generally collected. Clinical data including initial and cumulative manifestations at enrollment were collected. Initial manifestations meant the manifestations that present before the first visit to a rheumatologist. Symptoms that patients had ever had until enrollment were defined as cumulative manifestations which were assessed using ACR classification criteria and the SLE disease activity index (SLEDAI). Disease damage was assessed by the Systemic Lupus International Collaborating Clinics/ACR damage index (SDI) which included 12 different organ systems (ocular, neuropsychiatric, renal, pulmonary, cardiovascular, peripheral vascular, gastrointestinal, musculoskeletal, skin, gonad, endocrine, and malignancy). To be considered in the SDI, most items must persist for at least 6 months. The survival data of follow-up have been collected by April 2016.

Autoantibody levels were also recorded including anti-double-stranded DNA, anti-Smith, anti-SSA/Ro, anti-SSB/La, anti-ribonucleoprotein (RNP), and anti-ribosomal RNP antibodies measured at local laboratories. Antiphospholipid antibodies including anticardiolipin, lupus anticoagulant, and anti-β2-glycoprotein-I antibodies were tested only if antiphospholipid syndrome was suspected. SLE disease activity was evaluated in all patients by SLEDAI at the time of enrollment.

Statistical analysis

Continuous variables were expressed as mean ± standard deviation (SD) for normal distribution or medians (interquartile ranges) for skewed distributions, while categorical variables were presented as numbers (n) and percentages. A Student's t-test was used for comparison of continuous variables, and Chi-square and Fisher's exact tests were used to compare categorical data. After adjusting for gender ratio differences, logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Kaplan-Meier survival analysis and log-rank test were used to compare outcomes. Because cause of death could not always be confidently ascribed, all-cause mortality was analyzed. All tests were two-tailed, and the level of statistical significance (P value) was set at 0.05. Statistical analyses were performed using SPSS version 19.0 software (SPSS Inc., Chicago, IL, USA).

Results

Demographics

Out of 2104 patients, 1984 were < 50 years old. A total of 225 patients were included in the cSLE group with an average age of 12.16 ± 2.92 years (range, 1.4–16.0 years), and 1759 patients comprised the aSLE group with an average age of 30.03 ± 8.85 years (range, 16.0–50.0 years). 83.1% were women in the cohort of cSLE patients, as well as 92.4% in aSLE group. There was no significant difference in the time to diagnosis between cSLE and aSLE group [Mann-Whitney test, P = 0.766; Table 1].

Table 1

Demographic data of patients with different SLE onset ages

Characteristics	cSLE (n = 225)	aSLE (n = 1759)	t/Z/χ2	P
Female, n (%)	187 (83.1)	1625 (92.4)	21.655*	0.001
Age of onset (years), mean ± SD	12.16 ± 2.92	30.03 ± 8.85	−30.049†	<0.001
Age at diagnosis (years), mean ± SD	13.35 ± 3.84	31.17 ± 9.35	−27.867†	<0.001
Time to diagnosis (months), median (range)	29.70 (9.69–62.49)	16.70 (4.00–55.39)	2.164‡	0.766

*χ2 values; †t values; ‡Z values. SD: Standard deviation; cSLE: Childhood-onset SLE; aSLE: Adult-onset SLE; SLE: Systemic lupus erythematosus.

Clinical features

The initial manifestations reported in both groups are summarized in Table 2. Fever (P < 0.001) as well as mucocutaneous (P < 0.001) and renal (P = 0.006) disorders were found to be significantly more frequent in cSLE patients as initial symptoms, while muscle and joint lesions were significantly less common compared to aSLE subjects (P < 0.001).

Table 2

Clinical features of patients with different SLE onset ages

Variables	cSLE (n = 225)	aSLE (n = 1759)	t/Z/χ2	P
Initial manifestation
Fever	134 (59.6)	627 (35.6)	48.234*	<0.001
Musculoskeletal	91 (40.4)	977 (55.5)	18.297*	<0.001
Mucocutaneous	149 (66.2)	941 (53.5)	13.050*	<0.001
Hemocytopenia	76 (33.8)	557 (31.7)	0.410*	0.522
Renal	75 (33.3)	437 (24.8)	7.509*	0.006
Neuropsychiatric	8 (3.6)	64 (3.6)	0.004*	0.950
Respiratory	11 (4.9)	94 (5.3)	0.082*	0.774
Clinical manifestation
Malar rash	134 (59.6)	848 (48.2)	10.274*	0.001
Discoid lesions	11 (4.9)	97 (5.5)	0.152*	0.697
Arthritis	87 (38.7)	994 (56.5)	25.275*	<0.001
Serositis	25 (11.1)	295 (16.8)	4.724*	0.030
Renal disorder	112 (49.8)	833 (47.4)	0.405*	0.525
Neurologic disorder	11 (4.9)	88 (5.0)	0.005*	1.000
ILD	5 (2.2)	70 (4.0)	2.285	0.173
PAH	6 (2.7)	63 (3.6)	0.732*	0.388
Leukocytopenia	43 (19.1)	425 (24.2)	2.823*	0.093
Thrombocytopenia	27 (12.0)	292 (16.6)	3.129*	0.077
Hypocomplementemia	142 (63.1)	1179 (67.0)	1.375*	0.241
SLEDAI	9.39 ± 6.89	9.74 ± 7.07	−0.709†	0.478
Autoantibody-positive
Anti-dsDNA	77 (34.2)	504 (28.7)	2.988*	0.084
Anti-Sm	37 (16.4)	290 (16.5)	0.045*	0.987
Anti-RNP	19 (8.4)	156 (8.9)	0.045*	0.833
Anti-SSA	48 (21.3)	428 (24.3)	0.984*	0.321
Anti-SSB	19 (8.4)	194 (11.0)	1.390*	0.238
APL	47/112 (42.0)	344/775 (44.4)	0.233*	0.629

Values are presented as mean ± SD, n (%) or n/N (%). *χ2 values; †t values. SD: Standard deviation; ILD: Interstitial lung disease; PAH: Pulmonary arterial hypertension; SLEDAI: SLE disease activity index; dsDNA: Double-stranded DNA; Sm: Smith; RNP: Ribonucleoprotein; SSA: Sjögren’s syndrome-related antigen A; SSB: Sjögren’s syndrome-related antigen B; APL: Antiphospholipid antibody; cSLE: Childhood-onset SLE; aSLE: Adult-onset SLE; SLE: Systemic lupus erythematosus.

A comparison of cSLE and aSLE clinical characteristics is shown in Table 2. The cSLE patients were found to present more frequently with malar rash (P = 0.001; OR, 0.624; 95% CI, 0.470–0.829) but less frequently with arthritis (P < 0.001; OR, 2.013; 95% CI, 1.512–2.679) and serositis (P = 0.030; OR, 1.629; 95% CI, 1.053–2.520). There was no significant difference in SLEDAI scores between cSLE and aSLE group (P = 0.478).

Laboratory findings

Autoantibody profiles and percentages of patients positive for different autoantibodies are shown in Table 2. There was no significant difference in laboratory data between the two groups.

Outcomes

In cSLE group, 23 patients had damage at baseline, and at follow-up, 30 had damages including nine new damages. In aSLE group, 207 patients had damage at baseline, and 336 had damages which included 162 new damages at follow-up. After controlling the influence of gender and time from onset to diagnosis, Cox regression indicated that childhood onset was the risk factor for organ damage in lupus patients (hazard ratio [HR] 0.335 [0.170–0.658], P = 0.001).

Until April 2016, the follow-up data of 1409 patients were collected. The 1-, 3-, and 5-year survival rates of cSLE patients were 98.5%, 97.4%, and 97.4%, respectively. As well, the 1-, 3-, and 5-year survival rates of aSLE patients were 99.5%, 98.9%, and 97.9%, respectively. The survival curves between the cSLE and aSLE groups had no significant difference as determined by the log-rank test (0.557, P = 0.455).

Discussion

SLE is a diverse disease varying by the age of onset.[1617] However, the association between age of onset and SLE in Chinese populations remains unclear. Based on the first nationwide multicenter registry,[18192021] our study prospectively investigated the clinical characteristics and survival of cSLE patients from over 30 provinces of China and compared them with adult-onset lupus patients.

Our study showed that fever as well as mucocutaneous and renal disorders occurred more frequently in cSLE patients as initial symptoms relative to adult-onset patient group. This finding was consistent with most previous studies from Asia, Europe, and Latin America[16222324] and supports the notion that cSLE is more active and associated with more inflammation than aSLE patients.[112526]

Previous studies have also reported renal involvement to be more common in cSLE patients.[1124] According to our data, there was a significantly higher incidence of renal involvement as an initial symptom in cSLE (P = 0.006) patients but not as a cumulative symptom (P = 0.569; OR, 0.922; 95% CI, 0.697–1.219). This is in accordance with the research from the Grupo Latino Americano de Estudio de Lupus database that found renal involvement frequency did not significantly differ between cSLE and aSLE patients.[16] Tan et al.[27] suggested that previous reports with positive renal results might be due to a referral bias since many cSLE patients were primarily diagnosed by pediatric nephrologists and not pediatric rheumatologists. Furthermore, since the gender effect was isolated in our analyses, the effect of age of onset on kidney symptoms is more accurately reflected in our study.

We found that the prevalence of neuropsychiatric involvements was not significantly different between Chinese cSLE and aSLE cohorts. Different races had conflicting results in this kind of comparing.[58910121628] Furthermore, this may due to the various definition of “neuropsychiatric.” Recently, the ACR defines 19 syndromes for neuropsychiatric SLE, which is not yet validated in pediatric patients.

The effect of onset age on SLE disease activity remains controversial. Utilizing CSTAR cohort data, we analyzed differences between cSLE and aSLE patients. Unlike previous studies,[11] we did not detect differences in SLEDAI scores between these groups. This might reflect similarities in clinical features among these groups, except for arthritis, rash, and fever, which did not substantially contribute to the total SLEDAI score.

Long-term outcomes were evaluated by assessing organ damages and mortality rate. Our study indicated that less damages were seen in cSLE as compared to that of aSLE (HR 0.335 [0.170–0.658], P = 0.001). This is in accordance with previous studies[29] and is not surprising since many items of damage were due to aging (cataracts, cardiovascular, peripheral vascular, diabetes mellitus, and malignancy). The mortality rate was similar in our two groups. While survival rates are high in our cohort, long-term follow-up is needed.

Limitations of our study include the inability to determine all comorbidities. Given the multicenter nature of data collection, we were unable to accurately capture the exact data about all medical information. Another limitation is that our data come from a prevalent cohort but not an inception cohort. We try to eliminate this error by controlling the variable of time from onset to diagnosis in Cox regression analysis. Moreover, our cohort sample is large enough to neglect this error. We will further validate these in future study.

In conclusion, this is the largest cohort of SLE from multicenter in China, for which demographic, clinical, immunological, and outcome data are available. cSLE has more fever, mucocutaneous and renal disorders as initial symptoms and has less arthritis and serositis as cumulative symptoms than that of aSLE patients. Five-year survival rates were very high for both groups, with a younger age of lupus onset associated with a slightly lower 5-year survival. Long-term study is needed for more information.

CSTAR Co-authors

Peking Union Medical College Hospital: Hong-Mei Song, Xue-Jun Zeng, Wen Zhang, Xiao-Mei Leng, Jin-Mei Su, Qun Shi, Xin You, Wen-Jie Zheng, Ying Jiang, Dong Xu, You Hou, Min Shen, Hua Chen, Xiao-Dan Gan, Chao-Jun Hu, Ai Xu.

The Affiliated Drum Tower Hospital of Nanjing University Medical School: Ling-Yun Sun.

Anhui Provincial Hospital: Xiang-Pei Li, Xiao-Mei Li.

The Affiliated Hospital of Bengbu Medical College: Zhi-Jun Li, Chang-Hao Xie.

The First Affiliated Hospital of Sun Yat-sen University: Xiu-Yan Yang.

The Second Hospital of Shanxi Medical University: Xiao-Feng Li, Jin-Li Ru.

Beijing Hospital Affiliated to the Ministry of Health of PRC: Ci-Bo Huang, Bei Lai.

China-Japan Friendship Hospital Affiliated to the Ministry of Health of PRC: Dong-Hai Wu.

Beijing Chao-Yang Hospital, Capital Medical University: Yi Zheng, Xiao-Hong Wen.

Xuanwu Hospital Affiliated to Capital Medical University: Xiao-Xia Li.

Beijing Friendship Hospital Affiliated to Capital Medical University: Ting Duan.

Beijing Children Hospital Affiliated to Capital Medical University: Cai-Feng Li.

Capital Institute of Pediatrics: Feng-Qi Wu.

Chinese People's Liberation Army General Hospital: Feng Huang, Jian Zhu.

Changhai Hospital Affiliated to the Second Military Medical University: Dong-Bao Zhao.

Changzheng Hospital Affiliated to the Second Military Medical University: Hu-Ji Xu.

Huashan Hospital Affiliated to Fudan University: He-Jian Zou, Hao-Min Qiu.

The First Affiliated Hospital of Anhui Medical University: Jian-Hua Xu, Li Mu.

Qilu Hospital of Shandong University: Xing-Fu Li.

The Second Affiliated Hospital of Zhejiang University School of Medicine: Hua-Xiang Wu.

The Third Affiliated Hospital of Sun Yat-sen University: Jie-Ruo Gu, Ou Jin.

The Second Affiliated Hospital of Guangzhou Medical College: Yi Tao.

Guangdong Provincial People's Hospital: Xiao Zhang, Guang-Fu Dong.

Xiangya Hospital, Central South University: Xiao-Xia Zuo, Yi-Sha Li.

The First Affiliated Hospital of Harbin Medical University: Zhi-Yi Zhang, Yi-Fang Mei.

The First Hospital of China Medical University: Wei-Guo Xiao, Hong-Feng Zhang.

Xijing Hospital Affiliated to the Fourth Military Medical University: Ping Zhu, Zhen-Biao Wu.

The Second Hospital of Lanzhou University: Yi Wang.

West China Hospital Affiliated to Sichuan University: Yi Liu.

The Affiliated Hospital of North Sichuan Medical College: Guo-Hua Yuan.

Sichuan Provincial People's Hospital: Bin Zhou.

The People's Hospital of Xinjiang Autonomous Region: Li-Jun Wu.

Jiangsu Provincial People's Hospital: Miao-Jia Zhang.

The First Affiliated Hospital of Zhengzhou University: Sheng-Yun Liu.

Shengjing Hospital Affiliated to China Medical University: Ning Zhang.

The First Affiliated Hospital of Shantou University Medical College: Qing-Yu Zeng.

Tianjin First Central Hospital: Wen-Cheng Qi, Feng Han.

The Affiliated Hospital of Bengbu Medical College: Zhi-Jun Li, Chang-Hao Xie.

Peking University First Hospital: Zhuo-Li Zhang, Yu Wang.

Peking University Shougang Hospital: Shu-Ling Han.

Beijing Jishuitan Hospital: Hui Song, Shu-Min Yan.

Fuxing Hospital Affiliated to Capital Medical University: Wen Luo, Pei-Lin Li.

Beijing Shunyi Hospital: Xiao-Min Liu.

Peking University Third Hospital: Xiang-Yuan Liu, Xiao-Li Deng.

South-West Hospital Affiliated to Third Military Medical University: Yong-Fei Fang.

The First People's Hospital of Foshan: Guo-Qiang Chen.

Fujian Provincial Hospital: He Lin.

The Second Affiliated Hospital of Fujian Medical University: Ling Lin.

Fuzhou General Hospital of Nanjing Military Region: Yi-Nong Li.

Zhongshan Hospital Affiliated to Fudan University: Lin-Di Jiang, Li-Li Ma.

The First Affiliated Hospital of Guangxi Medical University: Cheng Zhao, Zhan-Rui Chen.

The People's Hospital of Guangxi Autonomous Region: Jin-Ying Lin.

The Affiliated Hospital of Guiyang Medical College: Long Li.

The Second Affiliated Hospital of Harbin Medical University: Yin-Huan Zhao.

Hainan Provincial People's Hospital: Feng Zhan, Shu-Dian Lin.

Hebei Provincial People's Hospital: Feng-Xiao Zhang, Yong-Long Yan.

Bethune International Peace Hospital: Zhen-Bin Li.

Henan Provincial People's Hospital: Feng-Min Shao, Wei Liu.

The First Hospital of Qiqihar: Xiao-Wei Gong.

Tongji Hospital Affiliated to Tongji Medical School of Huazhong University of Science and Technology: Shao-Xian Hu.

Jiangxi Provincial People's Hospital: You-Lian Wang.

No. 202 Hospital of People's Liberation Army: Yi-Ping Lin, Lin Guo.

The Affiliated Hospital of Inner Mongolia Medical College: Hong-Bin Li.

Nanfang Hospital Affiliated to Southern Medical University: Min Yang.

The General Hospital of Ningxia Medical University: Yi Gong, Hong Zhu.

The Affiliated Hospital of Qingdao University Medical College: Ji-Bo Wang.

The Fourth People's Hospital of Shenzhen Affiliated to Guangdong Medical College: Zhi-Zhong Ye, Zhi-Hua Yin.

The General Hospital of Tianjin Medical University: Lu Gong.

Beijing Tongren Hospital Affiliated to Capital Medical University: Zhen-Gang Wang, Li Cui.

The Second People's Hospital of Wuxi: Tian-Li Ren.

The People's Hospital of Wuxi: Yao-Hong Zou.

The Second Xiangya Hospital of Central South University: Jin-Wei Chen, Ni Mao.

The First People's Hospital of Yunnan Province: Qin Li.

The First Affiliated Hospital of Zhejiang University School of Medicine: Jin Lin.

Sun Yat-sen Memorial Hospital, Sun Yat-sen University: Lie Dai, Bai-Yu Zhang.

The First People's Hospital of Changzhou: Min Wu, Wen Xie.

The Affiliated Orthopaedic Hospital of Shandong Linyi People's Hospital: Zhen-Chun Zhang.

Zhejiang Provincial People's Hospital: Zhen-Hua Ying.

The First Affiliated Hospital of Baotou Medical College: Yong-Fu Wang.

The Affiliated Hospital of Nantong University: Zhan-Yun Da, Gen-Kai Guo.

The First Affiliated Hospital of Suzhou University: Zhi-Wei Chen.

Beijing Shijitan Hospital: Mian-Song Zhao.

Shandong Yantai Yuhuangding Hospital: Wei-Ling Yuan.

The General Hospital of Daqing Oilfield: Xiang-Jie Bi.

First Affiliated Hospital of Medical College of Xi’an Jiaotong University: Lan He, Dan Pu.

Provincial Hospital Affiliated to Shandong University, Jinan, China: Yuan-Chao Zhang, Li-Min Zhang.

Ji’nan University Second Clinical Medicine College, Shenzhen People's Hospital: Dong-Zhou Liu, Xiao-Ping Hong.

No. 285 Hospital of People's Liberation Army: Zhu Chen.

The First Hospital of Shanxi Medical University: Xiu-Mei Liu, Yi-Qun Hao.

Kailuan Hospital Affiliated to North China Coal Medical College: Liu-Fu Cui.

Peking University Shenzhen Hospital: Qing-Wen Wang, Yi-Sheng Zhu.

The First Affiliated Hospital of Fujian Medical University: Jun-Min Chen.

The First Hospital of Ningbo: Xia-Fei Xi.

Shanxi Provincial People's Hospital: Li-Hua Fang.

The Second Hospital of Hebei Medical University: Hong-Tao Jin, Hui-Fang Guo.

The First Affiliated Hospital of Wenzhou Medical College: Xiao-Chun Zhu.

The Third Affiliated Hospital of Hebei Medical University: Ping Wei.

The First Affiliated Hospital of Xinjiang Medical University: Li Wei.

Qingdao Municipal Hospital: Hou-Heng Su.

Wuhan Union Hospital Affiliated to Tongji Medical School of Huazhong University of Science and Technology: Ling-Xun Shen.

No. 264 Hospital of People's Liberation Army: Jin-Li Ru, Xiao-Xiang Xie.

Zhongda Hospital Affiliated to Southeast University: Mei-Mei Wang.

The Central Hospital of Sichuan Mianyang: Jing Yang, Yu Zhang.

The Seventh People's Hospital of Shenyang: Zhen Wang, Tie-Nan Li.

Financial support and sponsorship

This work was supported by grants from the Chinese National High Technology Research and Development Program, Ministry of Science and Technology (No. 2012AA020830), the Chinese National Key Technology R&D Program, Ministry of Science and Technology (No. 2008BAI59B02).

Conflicts of interest

There are no conflicts of interest.