Ten-year in-hospital mortality trends among Japanese injured patients by age, injury severity, injury mechanism, and injury region: A nationwide observational study.

The Injury Severity Score (ISS) is widely used in trauma research worldwide. An ISS cutoff value of ≥16 is frequently used as the definition of severe injury in Japan. The mortality of patients with ISS ≥16 has decreased in recent years, owing to the developing the trauma care system. This study aimed to analyze the prevalence, in-hospital mortality, and odds ratio (OR) for mortality in Japanese injured patients by age, injury mechanism, injury region, and injury severity over 10 years. This study used the Japan Trauma Data Bank (JTDB) dataset, which included 315,614 patients registered between 2009 and 2018. 209,290 injured patients were utilized. This study evaluated 10-year trends of the prevalence and in-hospital mortality and risk factors associated with in-hospital mortality. The overall in-hospital mortality was 10.5%. During the 10-year study period in Japan, the mortality trend among all injured patient groups with ISS 0-15, 16-25, and ≥26 showed significant decreases (p <0.001). Moreover, the mortality risk of patients with ISS ≥26 was significantly higher than that of patients with ISS 0-15 and 16-25 (p <0.001, OR = 0.05 and p<0.001, OR = 0.22). If we define injured patients who are expected to have a mortality rate of 20% or more as severely injured, it may be necessary to change the injury severity definition according to reduction of trauma mortality as ISS cutoff values to ≥26 instead of ≥16. From 2009 to 2018, the in-hospital mortality trend among all injured patient groups with ISS 0-15, 16-25, and ≥26 showed significant decreases in Japan. Differences were noted in mortality trends and risks according to anatomical injury severity.

Introduction

Injury has been a major cause of death in Japan over the past few decades [1]. The Japan Trauma Data Bank (JTDB) was established to improve the quality of trauma care by collecting and analyzing data from injured patients [2, 3]. As direct comparison of the outcome of injured patients with different severities of injury is often noninformative and misleading, injury severity is an important factor to be considered when analyzing mortality and morbidity based on a nationwide trauma registry [4]. Therefore, it is essential to consider risk-adjusted outcome measurements such as trauma scores while using a nationwide database, which includes patients with various severities of injury [4, 5].

Trauma scores were developed to describe the injury severity or prognosis of injured patients with a single numerical value. Injury Severity Score (ISS) is the most widely used trauma score in trauma research worldwide [4-6]. As the ISS score is calculated based on an anatomical injury severity and correlates well with the mortality of injured patients, an ISS cutoff value of ≥16 was chosen as the definition of severe injury with high mortality risk based on the Major Trauma Outcome Study (MTOS) from 1982 to 1987, because patients with ISS ≥16 had an expected mortality rate of more than 20% [6-9]. Epidemiological trauma outcome research based on the JTDB data also frequently used an ISS cutoff value of ≥16 as the definition of severe injury [10-12].

The mortality of patients with trauma has decreased in recent years due to the development of the trauma care system [9-11]. Moreover, the mortality trend and risk of severely injured patients vary widely according to age, injury mechanism, injury region, and/or injury severity [3, 10–13]. However, to the best of our knowledge, no long-term study has evaluated the mortality trends and risks of injured patients in a Japanese cohort using detailed classification of age and/or injury severity. Therefore, this 10-year nationwide study aimed to analyze the prevalence, in-hospital mortality, and odds ratio (OR) for mortality in Japanese injured patients by age and injury severity including injury mechanism and injury region.

Materials and methods

Study setting and patient population

This retrospective observational nationwide study used data from the JTDB, which included data on demographic characteristics, comorbidities, means of transportation, injury mechanism, injury region indicated by the abbreviated injury scale (AIS) score, vital signs, prehospital/in-hospital procedures, and clinical outcomes. In 2018, there were 280 participating hospitals in all 47 prefectures in Japan [2]. The Japan Association for the Surgery of Trauma permitted open access and updating of existing medical information, and the Japan Association for Acute Medicine evaluated the submitted data [2].

This study used the JTDB dataset, which included 315,614 patients registered between January 1, 2009, and December 31, 2018. The inclusion criteria for this study were injured patients who were transferred from the scene of injury by an ambulance car and/or helicopter. Patients with burns and missing data on age, gender, injury mechanism, ISS, and/or survival outcome were excluded from this study. Fig 1 presents a flow diagram of the patient selection in this study and S1 Table presents number of patients with missing data by study year.

Fig 1

Flow diagram of the study patient selection for this study.

Ethics statement

The study was conducted in accordance with the guidelines of the Declaration of Helsinki and approved by the Institutional Ethics Committee of Yokohama City University Medical Centre (approval no. B170900003). The approval for data access was provided by the Japanese Association for the Surgery of Trauma (Trauma Registry Committee). The requirement for informed consent from the patients was waived due to the observational nature of the study design.

Data collection and outcome measurements

We collected information on the following variables from the JTDB: demographic characteristics (age in years, gender, year of hospital admission); clinical parameters (injury mechanism, AIS of the injured region, ISS, Glasgow Coma Scale (GCS) score, systolic blood pressure (sBP), and heart rate (HR) at hospital admission); and outcomes (in-hospital mortality). The outcome measurements included the proportion of patients and in-hospital mortality according to the 10 groups categorized based on the hospital admission year from 2009–2018 split into nine age groups (0−4, 5−14, 15−24, 25−34, 35−44, 45−54, 55−64, 65−74, and ≥75 years old), two groups based on injury mechanism (blunt, penetrating injury), nine groups based on two or more injury regions with AIS ≥3 (polytrauma, head injury, facial injury, neck injury, chest injury, abdominal and pelvic injury, spinal injury, upper extremity injury, and lower extremity injury), and three groups based on injury severity (ISS 0−15, 16−25, and ≥26), which were classified according to previous studies [3, 6, 10–13].

Statistical analysis

This study evaluated the following: (1) 10-year trends in prevalence and in-hospital mortality by age, injury mechanism, and injury region with two or more injuries with AIS ≥3; and (2) risk factors associated with in-hospital mortality over 10 years. In the primary analysis, the Jonckheere-Terpstra trend test was used to test for trends in continuous variables, and the Cochran-Armitage trend test was used to test for trends in categorical variables by hospital admission year. In the secondary analysis, the OR (95% confidence interval [CI]) for in-hospital mortality was calculated using a logistic regression model. The following variables were included in the multivariable logistic regression analyses: admission year, age, injury mechanism, two or more injury regions with AIS ≥3, and ISS. The dependent variable in the multivariable logistic regression analysis was in-hospital mortality. The results were expressed as medians and interquartile ranges (IQR, Q1–Q3) for continuous variables, and patient numbers and percentages for categorical variables. All statistical analyses were performed using the STATA/SE software (version 17.0; StataCorp; College Station, TX, USA). Statistical significance was defined as a two-tailed P-value <0.05.

Results

During the 10-year study period, we utilized data from a total of 209,290 injured patients (Fig 1). These patients were categorized into the following age groups: 0–4 years (n = 2021, 1%); 5–14 years (n = 7519, 4%); 15–24 years (n = 20,909, 10%); 25–34 years (n = 16,017, 8%); 35–44 years (n = 19,575, 9%); 45–54 years (n = 21,674, 10%); 55–64 years (n = 26,866, 13%); 65–74 years (n = 33,898, 16%); and ≥75 years (n = 60,811, 29%). The number of patients with ISS 0–15, 16–25, and ≥26 was 1,18,547 (57%), 57,745 (28%), and 32,998 (16%), respectively. The median age and ISS score were 61 years (IQR, 38–77) and 13 (IQR, 9–21), respectively. The median GCS score, sBP, and HR at hospital admission was 15 (IQR, 13–15), 135 (IQR, 114–157), and 20 (IQR, 16–24), respectively. The overall in-hospital mortality rate was 10.5%.

The 10-year in-hospital mortality trends of all injured patients are shown in Table 1. In the Cochran-Armitage trend test, the in-hospital mortality of all injured patients significantly decreased from 13.7% in 2009 to 9.1% in 2018 (p <0.001). Similarly, the in-hospital mortality rates in patients with ISS 0–15, 16–25, and ≥26 showed significant decrease (from 2.5% to 1.8%, p = 0.000; from 15.6% to 10.4%, p <0.001; from 43.1% to 35.0%, p <0.001, respectively; Fig 2).

Table 1

Demographics and characteristics of injured patients by year groups.

Variables	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	p-value
	n = 10,596	n = 13,857	n = 16,833	n = 21,320	n = 25,556	n = 26,627	n = 26,852	n = 21,067	n = 23,247	n = 23,335
Male, n (%)	6869 (65)	9046 (65)	10,894 (64)	13,595 (64)	16,067 (63)	16,833 (63)	16,982 (63)	13,313 (63)	14,621 (63)	14,520 (62)	<0.001
Age in year, (median, IQR)	56 (32−73)	56 (32−73)	58 (35−74)	60 (36−75)	61 (37−77)	62 (38−77)	63 (39−78)	63 (40−78)	65 (42−79)	66 (44−79)	<0.001
Age groups, n (%)
Patient age 0–4	109 (1)	147 (1)	152 (1)	200 (1)	245 (1)	261 (1)	249 (1)	203 (1)	221 (1)	234 (1)	0.812
Patient age 5–14	402 (4)	572 (4)	646 (4)	771 (4)	989 (4)	1005 (4)	889 (3)	768 (4)	785 (3)	692 (3)	<0.001
Patient age 15–24	1328 (13)	1677 (12)	1872 (11)	2251 (11)	2645 (10)	2602 (10)	2620 (10)	1946 (9)	2014 (9)	1954 (8)	<0.001
Patient age 25–34	1078 (10)	1379 (10)	1452 (9)	1829 (9)	2025 (8)	1951 (7)	1942 (7)	1431 (7)	1505 (6)	1425 (6)	0.027
Patient age 35–44	1136 (11)	1531 (11)	1828 (11)	2150 (10)	2482 (10)	2506 (9)	2480 (9)	1779 (8)	1931 (8)	1752 (8)	<0.001
Patient age 45–54	1082 (10)	1417 (10)	1713 (10)	2164 (10)	2578 (10)	2706 (10)	2830 (11)	2243 (11)	2383 (10)	2558 (11)	0.004
Patient age 55–64	1612 (15)	1964 (14)	2447 (15)	2994 (14)	3361 (13)	3372 (13)	3245 (12)	2489 (12)	2698 (12)	2684 (12)	<0.001
Patient age 65–74	1479 (14)	1986 (14)	2536 (15)	3347 (16)	3931 (15)	4346 (16)	4536 (17)	3639 (17)	3987 (17)	4111(18)	0.221
Patient age ≥75	2370 (22)	3184 (23)	4187 (25)	5614 (26)	7300 (29)	7878 (30)	8061 (30)	6569 (31)	7723 (33)	7925 (34)	<0.001
Blunt injury, n (%)	10,110 (95)	13,246 (96)	16,141 (96)	20,438 (96)	24,606 (96)	25,687 (96)	25,940 (97)	20,386 (97)	22,515 (97)	22,654 (97)	<0.001
Injury region, n (%)
Polytrauma	2303 (22)	3071 (22)	3584 (21)	4143 (19)	4613 (18)	4733 (18)	4859 (18)	3998 (19)	4268 (18)	4150 (18)	<0.001
Head injury with AIS ≥3	2307 (22)	2859 (21)	3546 (21)	4412 (21)	5067 (20)	5400 (20)	5443 (20)	4334 (21)	4747 (20)	4974 (21)	0.573
Facial injury with AIS ≥3	18 (0.2)	27 (0.2)	39 (0.2)	41 (0.2)	55 (0.2)	56 (0.2)	56 (0.2)	42 (0.2)	50 (0.2)	41 (0.2)	0.881
Neck injury with AIS ≥3	29 (0.3)	44 (0.3)	51 (0.3)	60 (0.3)	59 (0.2)	61 (0.2)	64 (0.2)	64 (0.3)	53 (0.2)	52 (0.2)	0.079
Chest injury with AIS ≥3	1186 (11)	1452 (10)	1688 (10)	2088 (10)	2583 (10)	2631 (10)	2736 (10)	2299 (11)	2328 (10)	2554 (11)	0.206
Abdominal and pelvic injury with AIS ≥3	274 (3)	335 (2)	367 (2)	446 (2)	513 (2)	484 (2)	433 (2)	347 (2)	350 (2)	413 (2)	<0.001
Spinal injury with AIS ≥3	600 (6)	851 (6)	1137 (7)	1342 (6)	1719 (7)	1851 (7)	1899 (7)	1492 (7)	1752 (8)	1688 (7)	<0.001
Upper extremity injury with AIS ≥3	277 (3)	407 (3)	520 (3)	627 (3)	806 (3)	880 (3)	872 (3)	759 (4)	700 (3)	814 (3)	<0.001
Lower extremity injury with AIS ≥3	1825 (17)	2402 (17)	3062 (18)	3963 (19)	4967 (19)	5406 (20)	5173 (19)	3739 (18)	4670 (20)	4810 (21)	<0.001
ISS, (median, IQR)	14 (9−24)	13 (9−24)	13 (9−24)	12 (9−21)	10 (9−20)	10 (9−20)	11 (9−20)	13 (9−21)	11 (9−20)	11 (9−20)	<0.001
Injury severity groups, n (%)
ISS 0−15	5595 (53)	7374 (53)	9006 (54)	12,071 (57)	14,974 (59)	15,544 (58)	15,539 (58)	11,729 (56)	13,303 (57)	13,412 (57)	<0.001
ISS 16−25	3044 (29)	3923 (28)	4761 (28)	5788 (27)	6785 (27)	7223 (27)	7230 (27)	6004 (29)	5403 (28)	6484 (28)	0.651
ISS ≥26	1957 (18)	2560 (18)	3066 (18)	3461 (16)	3797 (15)	3860 (15)	4083 (15)	3334 (16)	3441 (15)	3439 (15)	<0.001
In-hospital mortality, n (%)	1456 (13.7)	1919 (13.9)	2152 (12.8)	2459 (11.5)	2591 (10.1)	2470 (9.3)	2597 (9.7)	2138 (10.2)	2156 (9.3)	2115 (9.1)	<0.001

IQR, Interquartile range; AIS, Abbreviated Injury Scale; ISS, Injury Severity Score

Fig 2

In-hospital mortality trends among injured patients according to ISS groups.

The in-hospital mortality trends among injured patients by age group, injury mechanism, and injury region according to three groups based on injury severity (ISS 0−15, 16−25, and ≥26) are shown in S2–S4 Tables. Among injured patients with age >15 years, in-hospital mortality of patients with ISS 16–25 and ≥26 significantly decreased over the 10-year study period (S2 Table). The in-hospital mortality among patients with blunt injury showed a significant decrease in all ISS groups (S3 Table). Moreover, in patients with ISS from 16–25, the in-hospital mortality of patients with polytrauma, head, chest, abdominal and pelvic, spinal, upper extremity, and lower extremity injuries with AIS ≥3 showed a significant decrease (S4 Table).

Table 2 shows the results of multivariable logistic analyses. The mortality risk of patients admitted in 2018 (comparative controls) was significantly lower than that of patients admitted before 2016. The mortality risk of patients aged ≥76 years was significantly higher than that of patients in other age categories. Patients with polytrauma, head, neck, chest, abdominal and pelvic, and lower extremity injury with AIS ≥3 were significantly associated with higher OR of in-hospital mortality. Moreover, the mortality risk of patients with ISS ≥26 was significantly higher than that of patients with ISS 0–15 and 16–25 (p <0.001, OR = 0.05, 95%CI = 0.045–0.051 and p <0.001, OR = 0.22, 95%CI = 0.206–0.224, respectively).

Table 2

Multivariable logistic regression analysis of in-hospital mortality among injured patients.

	All patients (n = 209,290)
	OR	95% CI	p value
Admission year groups
2009	1.63	(1.502–1.763)	<0.001
2010	1.66	(1.544–1.791)	<0.001
2011	1.48	(1.377–1.587)	<0.001
2012	1.39	(1.301–1.492)	<0.001
2013	1.26	(1.174–1.343)	<0.001
2014	1.11	(1.035–1.185)	0.003
2015	1.12	(1.052–1.202)	0.001
2016	1.12	(1.042–1.199)	0.002
2017	1.05	(0.976–1.122)	0.201
2018	1.00	–
Age groups
Patient age 0–4	0.43	(0.351–0.518)	<0.001
Patient age 5–14	0.20	(0.175–0.230)	<0.001
Patient age 15–24	0.39	(0.369–0.418)	<0.001
Patient age 25–34	0.49	(0.462–0.526)	<0.001
Patient age 35–44	0.51	(0.483–0.544)	<0.001
Patient age 45–54	0.53	(0.497–0.557)	<0.001
Patient age 55–64	0.56	(0.530–0.588)	<0.001
Patient age 65–74	0.66	(0.634–0.696)	<0.001
Patient age ≥75	1.00	–
Injury mechanism
Blunt injury	0.59	(0.533–0.652)	<0.001
Penetrating injury	1.00	–
Injury region
Polytrauma	2.95	(2.618–3.336)	<0.001
Head injury with AIS ≥3	3.48	(3.094–3.913)	<0.001
Facial injury with AIS ≥3	1.11	(0.492–2.524)	0.794
Neck injury with AIS ≥3	8.73	(6.708–11.350)	<0.001
Chest injury with AIS ≥3	3.13	(2.775–3.536)	<0.001
Abdominal and pelvic injury with AIS ≥3	3.90	(3.326–4.563)	<0.001
Spinal injury with AIS ≥3	0.82	(0.704–0.944)	0.006
Upper extremity injury with AIS ≥3	0.76	(0.572–1.001)	0.051
Lower extremity injury with AIS ≥3	1.48	(1.313–1.674)	<0.001
Injury severity groups, n (%)
ISS 0−15	0.05	(0.045–0.051)	<0.001
ISS 16−25	0.22	(0.206–0.224)	<0.001
ISS ≥26	1.00	–

OR, odds ratio; CI, confidence interval; AIS, Abbreviated Injury Scale; ISS, Injury Severity Score.

Discussion

This 10-year nationwide study in Japan showed that the in-hospital mortality trend significantly decreased in all injured patient groups with ISS 0–15, 16–25, and ≥26. However, there were differences in the mortality trends and risk according to the age, injury mechanism, injury region, and anatomical severity. Moreover, the in-hospital mortality and OR for mortality in the patient group with ISS ≥26 were higher than those in two patient groups with ISS 0−15 and 16−25.

There were significant differences in the mortality risk of injured patients according to the severity of anatomical injury. Previous studies have shown that the mortality of injured patients with ISS ≥16 has been decreasing to below 20% [9–11, 13]. This study also showed that the mortality rate of injured patients with ISS 0–15 and 16–25 in 2018 was 20% or less, regardless of age, injury mechanism, and injury region. Moreover, the OR for mortality of injured patients with ISS 0–15 and 16–25 was significantly lower than that of patients with ISS ≥16 (0.05 and 0.22 vs 1.00, p <0.001). The ISS cutoff value of ISS ≥16 has been commonly used as the definition of severe injury in Japanese trauma research [10–12, 14]. However, it may be necessary to change the definition of severe injury to include those having ISS cutoff values of ≥26 instead of ≥16, since trauma mortality trend has decreased and OR for mortality of injured patients with ISS ≥26 was relatively higher than those of patients with ISS 0−15 and 16−25 in the past decades.

In this study, there were specific injured patients with a high mortality risk in whom the mortality trend also remained unimproved from 2009 to 2018. First, the mortality risk and trend of injured patients varied significantly according to age (S2 Table and Table 2). In patients aged ≥15 years, the mortality risk increased steadily with increasing age, and the mortality rate of elderly patients with ISS ≥26 remained high despite the improvement in mortality trends of elderly patients with ISS ≥16. Japan has the most rapidly increasing number of aging citizens in the world, and the proportion of elderly patients aged > 75 years with the highest mortality risk accounted for 34% of this study cohort in 2018. As Japan is expecting a rapid change in its population structure with a growing elderly population, it is important to establish a trauma care system suitable for such patients to improve mortality by considering their age-related characteristics and various mortality risks. In patients aged younger than 15 years, the mortality trend in injured patients with ISS ≥26 did not significantly improve, and the in-hospital mortality risk of patient aged 0−4 years with ISS ≥26 remained high during the 10 years of study (26.1%−58.3%). Previous studies suggested that injured patients younger than 5 years had a higher mortality risk, because they included a high proportion of severe head injuries [11, 15]. Our results also showed that the OR for mortality in patients with head injury and AIS ≥3 was 3.48. Therefore, it may be important to establish the therapeutic strategies suitable for patients with severe head injuries to decrease the mortality risk of younger injured patients in Japan. Second, our results showed that the mortality risk of patients with penetrating injury was 1.7 times higher than that of patients with blunt injury (Table 2), as shown in a previous study that used JTDB data from 2004 to 2011. The mortality trend in patients with penetrating injuries with ISS 0−15 and ≥26 did not decrease significantly, and the mortality rate of patients with penetrating injuries with ISS ≥26 remained extremely high from 40.0% to 51.3%, despite the improvements seen in blunt injury patients regardless of the anatomical severity. Furthermore, in patients with a significantly high mortality risk due to polytrauma or injury regions with AIS ≥3, such as head, neck, chest, abdominal and pelvic, or lower extremity injury, the mortality trends in those with neck injury and abdominal/pelvic injury and ISS ≥26 did not improve. A previous study suggested that the survival benefit in patients with severe head injury, penetrating injury, pelvic injury, and solid organ injury may be improved by centralization to trauma centers with a higher quality of trauma care [16]. Several studies have also suggested that centralizing patients with penetrating injury or pediatric injured patients to higher-volume hospitals may contribute to the survival benefit [17, 18]. Therefore, it is necessary to achieve a trauma care system that centralizes specific severely injured patients to hospitals with a high volume and quality to improve their outcomes, based on the results of a nationwide clinical research based on the injury mechanism and region.

Our study had some limitations. First, there was a selection bias, as not all Japanese hospitals participated in the JTDB registry, and the number of participating hospitals varied across the 10-year study period. Moreover, there were missing data in the JTDB dataset. Second, the results of the trend test analyzing the small study cohort resulted in biased conclusions. Third, with regards to the trauma score for predicting injury severity and mortality, several studies have reported that are based on not only anatomical severity, but also on physiological factors and results of blood test, which may be more useful and accurate to define severe injury in patients with high mortality risk [6, 13, 18]. In the future, it is necessary to evaluate not only anatomical severity but physiological variables and examination results as the predictor of trauma mortality.

Conclusions

From 2009 to 2018, the in-hospital mortality trend among all injured patient groups with ISS 0–15, 16–25, and ≥26 showed significant decreases in Japan. Differences were noted in mortality trends and risks according to age, injury mechanism, injury region, and anatomical injury severity. For specific patients with older age, those with penetrating injury, and/or those with specific injury regions with AIS ≥3, it may be necessary to change the definition of these patients according to trauma mortality.

(XLSX)

Click here for additional data file.

Number of patients with missing data by study year.

Some fitted into more than one variable.

(DOCX)

Click here for additional data file.

In-hospital mortality trends among injured patients by age groups and ISS groups.

ISS, Injury Severity Score.

(DOCX)

Click here for additional data file.

In-hospital mortality trends by injury mechanism and ISS groups.

ISS, Injury Severity Score.

(DOCX)

Click here for additional data file.

In-hospital mortality trends by injury region and ISS groups.

AIS, Abbreviated Injury Scale; ISS, Injury Severity Score.

(DOCX)

Click here for additional data file.

22 Apr 2022

Please addressed questions and comments raised by the reviewer 1, especially related to abstract and methods.

Data should be made available as per PLOS's data policy.

==============================

Please submit your revised manuscript by Jun 06 2022 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're 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.

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). You should upload this letter as a separate file labeled 'Response to Reviewers'.

A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.

An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Tze-Woei Tan, M.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

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

2. Thank you for stating the following financial disclosure:

“C.T. received a grant from the General Insurance Association of Japan [Grant No.21-08].”

Please state what role the funders took in the study.  If the funders had no role, please state: "The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript."

If this statement is not correct you must amend it as needed.

Please include this amended Role of Funder statement in your cover letter; we will change the online submission form on your behalf.

[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: Partly

Reviewer #2: Yes

**********

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

Reviewer #1: Yes

Reviewer #2: 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: No

Reviewer #2: No

**********

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

**********

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: The Injury Severity Score (ISS) is an established scoring system for accessing the severity of injury across the world. In Japan, ISS score > 16 is used to define severe trauma. Authors performed a 10 year analysis retrospective analysis of the Japanese Trauma National Bank (JTNB) stratifying patient based on ISS score. They determined the mortality over the years stratifying by ISS score and found a decreasing trend in the mortality and higher mortality with higher ISS score. Based on the mortality rate, they recommended using a higher ISS score cut off to define severely injured trauma patients. The authors do good job in the study to help answer the question they sought out to answer however, I have a few questions and revision regarding the study

P2 L24: The authors mention ISS Score > 16 is used to define severe trauma in Japan. In the United States and across the world, ISS Score of > 15 is used to define severe trauma. Can you clarify why this difference

P2 L28: The aim cannot be to validate. To validate, you need a different dataset.

P2 L29: Please write down the full form of JTNB

P2: The abstract is missing methods section and details of the study as the authors jump into results

P2: L32: Please add p value

P2: L33-37 can be deleted and kept for the manuscript. It confuses the reader and not relevant for the aim

P2: L40: The conclusion needs to be what they find and not another hypothesis. The found lower mortality in the ISS group 16-25 and has been decreasing. Based on this they suggest a change in cut off to ISS score of > 26

P3 L58-60: The authors mention ISS Score > 16 is used to define severe trauma in Japan. In the United States and across the world, ISS Score of > 15 is used to define severe trauma. Can you clarify why this difference

P3: L63-65: The mortality has decreased and other factors like mentioned by authors are contributing. Multiple scoring systems have been used like Revised Trauma Score (RTS), Trauma Injury Severity Score (TRISS) and New Injury Score. What do the authors think about comparing ISS with TRISS which has becoming the standard scoring system.

P4: L69-71: Please edit the aim as per the abstract

P4: L86-88: Can you please include the excluded patient each year. It would be good to know that so missing bias may be limited. Do not want a lot of patient missing in the earlier years compared to recent years. I would anticipate the proportion of missing patients be equal across the years.

P4: Do you have GSC score or patient admission BP and HR data? That may be useful to add

P4: L88: The figure 1 is excellent and adding excluded patient based on year will be helpful

P4L L92: Please change sex to gender

P5: L95: Why divide into 9 groups age groups? Is that the way data reported in the JTNB?

P5: A very good description of the methods

P6: Ethics statement can be moved after study settling and patient poplutation

P6: Result paragraph one, can some of the statement deleted. Most of the information is in the table

P7-14: Please edit result. Focus on the aim result decrease mortality with increasing ISS. The stratification by age, AIS, blunt etc

P7: May be a figure demonstrating Mortality rate and ISS score will help to make the point stronger. The table looks overwhelming

P9: Table 2 although a lot of work, does not add more much to the aim of the study

P12: Table 4 although a lot of work, does not add more much to the aim of the study

P11-12: May be change the table 3 and 4 into figures or have them as supplement

P15: L188-194: Please edit to focus on 1: decrease mortality with increasing ISS. The age, AIS etc are all subanalysis.

P15: L195-202: the paragraph does not add much context to the study. I would add a paragraph focusing on the main result regarding ISS and mortality

P16: L219: Please move this paragraph above the paragraph about the age and mortality as that was not the focus. Also please edit to clear to focus how it aligns with your study

P17: L238-: please move this paragraph as a second paragraph as this is the focus

P17: L250: There are more limitations to the study like GCS, vitals not recorded, missing data, not compared to other major scoring system like TRISS

P17: L261: I think defining ISS > 26 as the new cut off without validation is a strong statement. May be it can be a suggestion or more studies need to be performed.

**********

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

[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.]

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 PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

6 Jun 2022

June 6, 2022

Dr. Tze-Woei Tan, M.D.,

Academic Editor

PLOS ONE

Dear Editors,

On behalf of all the authors, I would like to thank you for your response and we thank the reviewers for their comments regarding our manuscript (PONE-D-22-05214) titled “Ten-year in-hospital mortality trends among Japanese injured patients by age, injury severity, injury mechanism, and injury region: A nationwide observational study.” We hope that the revised version of the manuscript will be moved closer to publication in PLOS ONE.

The manuscript has been modified in accordance with the extensive and insightful comments from the reviewers. The point-by-point responses to all comments have been prepared and given below. The revised manuscript is attached herewith. Please find the modifications in the revised manuscript marked in red font. Moreover, please permit that the number of words of the abstract exceeded the recommended limit because of having revised it according to reviewers’ comment.

C.T. received a grant from the General Insurance Association of Japan [Grant No.21-08]. The funders had no role in this study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Please do not hesitate to contact us for further clarifications regarding our manuscript. Thank you for your consideration. I look forward to hearing from you.

Sincerely,

Chiaki Toida

Department of Disaster Medical Management, University of Tokyo

7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan

Phone: +81-3-3815-5411

Fax: +81-3-3814-6446

E-mail: toida-ygc@umin.ac.jp

Reviewer’s comments (in blue) and Answers (in black) follow.

We wish to express our deep appreciation for the valuable comments from the Reviewer regarding our manuscript. We believe that our manuscript has benefited greatly from these comments.

Reviewer: 1

1. P2 L24: The authors mention ISS Score > 16 is used to define severe trauma in Japan. In the United States and across the world, ISS Score of > 15 is used to define severe trauma. Can you clarify why this difference

Response: We thank the Reviewer for this comment. We used patients with ISS ≥16 and ISS >15 as the same meaning, because the groups were divided into three, based on injury severity (ISS 0−15, 16−25, and ≥26). We included the definition of severe trauma as ISS ≥ 16 not ISS > 15.

2. P2 L28: The aim cannot be to validate. To validate, you need a different dataset.

Response: We thank the Reviewer for this suggestion. We agree with this suggestion. We revised the aim of this study in the Abstract as follows.

This study aimed to analyze the prevalence, in-hospital mortality, and odds ratio (OR) for mortality in Japanese injured patients by age, injury mechanism, injury region, and injury severity over 10 years.

3. P2 L29: Please write down the full form of JTNB

Response: Thank you for your comment. JTDB has been spelled out in the Abstract as follows.

the Japan Trauma Data Bank (JTDB)

4. P2: The abstract is missing methods section and details of the study as the authors jump into results

Response: We thank the Reviewer this suggestion. We added the details of this study method in the Abstract as follows.

This study evaluated 10-year trends of the prevalence and in-hospital mortality and risk factors associated with in-hospital mortality.

5. P2: L32: Please add p value

Response: As you pointed out, we added p value as p < 0.001.

6. P2: L33-37 can be deleted and kept for the manuscript. It confuses the reader and not relevant for the aim

Response: We thank the Reviewer for this valuable suggestion. We strongly agree with your comment. We deleted these sentences.

7. P2: L40: The conclusion needs to be what they find and not another hypothesis. The found lower mortality in the ISS group 16-25 and has been decreasing. Based on this they suggest a change in cut off to ISS score of > 26

Response: We thank the Reviewer suggestion. We revised the Conclusion according to your comment 7 and 24 as follows.

From 2009 to 2018, the in-hospital mortality trend among all injured patient groups with ISS 0–15, 16–25, and ≥26 showed significant decreases in Japan. Differences were noted in mortality trends and risks according to anatomical injury severity.

8. P3 L58-60: The authors mention ISS Score > 16 is used to define severe trauma in Japan. In the United States and across the world, ISS Score of > 15 is used to define severe trauma. Can you clarify why this difference

Response: As mentioned above, we used patients with ISS ≥ 16 and ISS > 15 as the same meaning. Because we split into three groups based on injury severity (ISS 0−15, 16−25, and ≥ 26), we mentioned the definition of severe trauma with ISS ≥16 not ISS >15.

9. P3: L63-65: The mortality has decreased and other factors like mentioned by authors are contributing. Multiple scoring systems have been used like Revised Trauma Score (RTS), Trauma Injury Severity Score (TRISS) and New Injury Score. What do the authors think about comparing ISS with TRISS which has becoming the standard scoring system.

Response: We thank the Reviewer for this valuable comment. In Japan, Epidemiological trauma outcome research based on the JTDB data also frequently used an ISS cutoff value of ≥16 as the definition of severe injury [10-12]. However, there is no long-term study evaluating the mortality trends and risk of injured patients in Japanese cohort by detailed classification of injury severity. Therefore, we aimed to analyze the prevalence, in-hospital mortality, and odds ratio (OR) for mortality in Japanese injured patients by anatomical injury severity, which is one of the predictors used to calculate the probability of survival by TRISS method. We revised the Introduction section as follows.

The mortality of patients with trauma has decreased in recent years due to the development of the trauma care system [9-11]. Moreover, the mortality trend and risk of severely injured patients vary widely according to age, injury mechanism, injury region, and/or injury severity [3, 10–13]. However, to the best of our knowledge, no long-term study has evaluated the mortality trends and risks of injured patients in a Japanese cohort using detailed classification of age and/or injury severity. Therefore, this 10-year nationwide study aimed to analyze the prevalence, in-hospital mortality, and odds ratio (OR) for mortality in Japanese injured patients by age and injury severity including injury mechanism and injury region.

10. P4: L69-71: Please edit the aim as per the abstract

Response: We thank the Reviewer for this suggestion. We agree to this suggestion. We revised the aim of this study in the Text as follows.

Therefore, this 10-year nationwide study aimed to analyze the prevalence, in-hospital mortality, and odds ratio (OR) for mortality in Japanese injured patients by age and injury severity including injury mechanism and injury region.

11. P4: L86-88: Can you please include the excluded patient each year. It would be good to know that so missing bias may be limited. Do not want a lot of patient missing in the earlier years compared to recent years. I would anticipate the proportion of missing patients be equal across the years.

Response: We thank the Reviewer for this comment. We showed the proportion of missing data across the study year in S1 Table, because it is difficult to show these data in Figure 1. Regrettably, there are not differences in the proportion of missing data by study years.

12. P4: Do you have GSC score or patient admission BP and HR data? That may be useful to add

Response: As you pointed out, we analyzed the data of GCS score, systolic BP, and HR at hospital admission. We revised the Method and Result section as follows.

Method

We collected information on the following variables from the JTDB: demographic characteristics (age in years, gender, year of hospital admission); clinical parameters (injury mechanism, AIS of the injured region, ISS, Glasgow Coma Scale (GCS) score, systolic blood pressure (sBP), and heart rate (HR) at hospital admission);…

Result

The median GCS score, sBP, and HR at hospital admission was 15 (IQR, 13–15), 135 (IQR, 114–157), and 20 (IQR, 16–24), respectively.

13. P4: L88: The figure 1 is excellent and adding excluded patient based on year will be helpful

Response: As mentioned above, we showed the proportion of missing data across the study year in S1 Table.

14. P4L L92: Please change sex to gender

Response: As you pointed out, we revised sex in gender.

15. P5: L95: Why divide into 9 groups age groups? Is that the way data reported in the JTNB?

Response: Owing to aging issues in Japan, the definition of the elderly was classified into two groups; early-stage elderly (person between 65-74 years old) and later-stage elderly (person over 75 years old). The annual report showed that these two groups have differences in the mortality and morbidity.

https://www8.cao.go.jp/kourei/english/annualreport/2021/pdf/2021.pdf

Moreover, in children, previous study showed that preschool children had higher mortality than the other age groups.

J Clin. Med. 2021, Clin. Med. 2021, 10, 1072. https://doi.org/ 10.3390/jcm10051072

Therefore, we divided in 9 age groups (0−4, 5−14, 15−24, 25−34, 35−44, 45−54, 55−64, 65−74, and ≥75 years old) in this study, as it is predicted that the mortality rates are different by age group.

16. P5: A very good description of the methods

Response: Thank you for your kindly comment.

17. P6: Ethics statement can be moved after study settling and patient poplutation

Response: As you pointed out, we moved the ethics statement to after the study setting and patients population.

18. P6: Result paragraph one, can some of the statement deleted. Most of the information is in the table

Response: We thank the Reviewer comment. We delated the most of information including the table 1 as follows.

A total of 201,723 patients (96%) had a blunt injury. The number of patients with two or more injury regions with AIS ≥ 3 was as follows: polytrauma (n = 39,722, 19%); head injury (n = 43,089, 21%); facial injury (n = 425, 0.2%); neck injury (n = 537, 0.3%); chest injury (n = 21,545, 10%); abdominal and pelvic injury (n = 3962, 2%); spinal injury (n = 14,331, 7%); upper extremity injury (n = 6662, 3%); lower extremity injury (n = 40,017, 19%).

19. P7: May be a figure demonstrating Mortality rate and ISS score will help to make the point stronger. The table looks overwhelming

Response: As you pointed out, we demonstrated 10-years mortality trends by ISS groups in Figure 2.

20. P7-14: Please edit result. Focus on the aim result decrease mortality with increasing ISS. The stratification by age, AIS, blunt etc

P9: Table 2 although a lot of work, does not add more much to the aim of the study

P12: Table 4 although a lot of work, does not add more much to the aim of the study

P11-12: May be change the table 3 and 4 into figures or have them as supplement

Response: We thank the Reviewer valuable comments. We agree that we focus on the mortality trend by ISS groups, decreasing the quantity of data presentation. Therefore, we added the Figure 2 which showed the mortality trends by ISS groups, and changed Table 2, 3 ,4 to Supplement Table 2, 3, 4. We revised the results as follows.

The in-hospital mortality trends among injured patients by age group, injury mechanism, and injury region according to three groups based on injury severity (ISS 0−15, 16−25, and ≥26) are shown in Table S2, S3, and S4. Among injured patients with age >15 years, in-hospital mortality of patients with ISS 16–25 and ≥26 significantly decreased over the 10-year study period (Table S2). The in-hospital mortality among patients with blunt injury showed a significant decrease in all ISS groups (Table S3). Moreover, in patients with ISS from 16–25, the in-hospital mortality of patients with polytrauma, head, chest, abdominal and pelvic, spinal, upper extremity, and lower extremity injuries with AIS ≥3 showed a significant decrease (Table S4).

22. P15: L188-194: Please edit to focus on 1: decrease mortality with increasing ISS. The age, AIS etc are all subanalysis.

Response: As you pointed out, we revised the Discussion as follows.

This 10-year nationwide study in Japan showed that the in-hospital mortality trend significantly decreased in all injured patient groups with ISS 0–15, 16–25, and ≥26. However, there were differences in the mortality trends and risk according to the age, injury mechanism, injury region, and anatomical severity. Moreover, the in-hospital mortality and OR for mortality in the patient group with ISS ≥26 were higher than those in two patient groups with ISS 0−15 and 16−25.

23. P15: L195-202: the paragraph does not add much context to the study. I would add a paragraph focusing on the main result regarding ISS and mortality

P16: L219: Please move this paragraph above the paragraph about the age and mortality as that was not the focus. Also please edit to clear to focus how it aligns with your study

P17: L238-: please move this paragraph as a second paragraph as this is the focus

Response: We thank the Reviewer for valuable suggestion. We agree with your suggestion. We deleted the second paragraph and revised the Discussion to focus on the main results regarding ISS and mortality by changing the order of paragraphs.

24. P17: L250: There are more limitations to the study like GCS, vitals not recorded, missing data, not compared to other major scoring system like TRISS

Response: As you pointed out, we added the limitation about other major scoring systems, including physiological factors and/or results of blood test as follows.

Third, with regards to the trauma score for predicting injury severity and mortality, several studies have reported that are based on not only anatomical severity, but also on physiological factors and results of blood test, which may be more useful and accurate to define severe injury in patients with high mortality risk [6,13,18]. In the future, it is necessary to evaluate not only anatomical severity but physiological variables and examination results as the predictor of trauma mortality.

25. P17: L261: I think defining ISS > 26 as the new cut off without validation is a strong statement. May be it can be a suggestion or more studies need to be performed.

Response: We thank the Reviewer for this valuable suggestion. We revised the Conclusion as follows.

From 2009 to 2018, the in-hospital mortality trend among all injured patient groups with ISS 0–15, 16–25, and ≥26 showed significant decreases in Japan. Differences were noted in mortality trends and risks according to age, injury mechanism, injury region, and anatomical injury severity. For specific patients with older age, those with penetrating injury, and/or those with specific injury regions with AIS ≥3, it may be necessary to change the definition of these patients according to trauma mortality.

Submitted filename: response report20220606.docx

Click here for additional data file.

22 Jul 2022

Ten-year in-hospital mortality trends among Japanese injured patients by age, injury severity, injury mechanism, and injury region: A nationwide observational study

PONE-D-22-05214R1

Dear Dr. Toida,

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

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. 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 help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- 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.

Kind regards,

Tze-Woei Tan, M.D.

Academic Editor

PLOS ONE

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

**********

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: Yes

Reviewer #2: Yes

**********

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

Reviewer #1: Yes

Reviewer #2: Yes

**********

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

Reviewer #2: Yes

**********

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: Yes

Reviewer #2: Yes

**********

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: The authors have addressed all the concerns raised and provided satisfactory explanation for the questions. They have revised the manuscript based on the concerns. The manuscript reads better. I have no further questions.

Reviewer #2: (No Response)

**********

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: No

Reviewer #2: Yes: Navdeep Samra, MD, FACS

**********

12 Aug 2022

PONE-D-22-05214R1

Ten-year in-hospital mortality trends among Japanese injured patients by age, injury severity, injury mechanism, and injury region: A nationwide observational study

Dear Dr. Toida:

I'm 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 let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, 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.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Tze-Woei Tan

Academic Editor

PLOS ONE