Traumatic spinal cord injury mortality from 2006 to 2016 in China

Abstract

Purpose: To report on the national traumatic spinal cord injury (TSCI) mortality of China population, and assess sex-, age-, location-, and cause-specific mortality rates, respectively.

Methods: A population-based longitudinal study based on mortality data from the Disease Surveillance Points system of China, 2006–2016. TSCI was defined according to the 10th International Classification of Disease. Negative binomial regression was used to test the significance of the change in overall and subgroup mortality rate.

Results: Age-adjusted TSCI mortality rate increased by 64% from 2006 to 2016, ranging from 0.19 to 0.34 per 100,000 population. The crude mortality was 0.31 per 100,000 population in 2016. Males and rural residents had higher TSCI mortality rates than females and urban residents. The age-adjusted TSCI mortality rate increased 53% for males, 107% for females, 75% in an urban area, and 59% in a rural area. In comparison with insignificant change in the age group of 0–44 years, TSCI mortality increased 56% and 147% in age groups of 45–64 years and 65 years. Falls accounted for 45.4% of total mortality.

Conclusions: TSCI mortality rates were higher in males and in rural residents than in females and in urban residents during the study time period. TSCI mortality increased quickly as age increased; adults aged 65 years and older had the highest mortality rate. Falls and motor vehicle crashes were the two most common causes of TSCI mortality. More prevention efforts are needed to reduce a number of deaths from TSCI injury considering a substantial increase in TSCI mortality.

Introduction

Traumatic spinal cord injury (TSCI) is a sudden and unexpected event. Although the incidence rates of TSCI are not very high, it has been associated with high mortality. A pooled population-based analysis of 22 European countries revealed age-standardized TSCI mortality rate ranging from 1.0 (95% confidence interval [CI]: 0.7–1.4) in Turkey to 21.4 (95% CI: 17.6–25.7) in Finland.¹ Motor vehicle crashes (MVCs), falls, and violence were reported as the major causes of TSCI.^2,3

TSCI mortality rates had been reported for many developed countries.^4–10 But TSCI mortality estimates were not reported for China, the country with the largest population over the world.

Using mortality data from the China Disease Surveillance Points (DSP) system, we examined changes in TSCI mortality from 2006 to 2016 in China.

Materials and methods

Ethics concerns

This secondary analysis was approved by the ethics committee (No. XYGW-2017-01) of Xiangya School of Public Health, Central South University. Data analyses were de-identified and informed consent was not required.

Study population

The study population was limited to the nationally representative surveillance sample covered by the DSPs of China. Details about the DSPs have been described in previous publications.¹¹ The DSPs have ever experienced substantial adjustments in 1989 and 2004–2005, to improve the coverage and representativeness of the surveillance samples to the total national population.¹² We used the data of 161 surveillance points that were continuously surveilled during 2006–2016 to eliminate the impact of changes to the DSPs in 2004–2005.

Definition of TSCI

The 10th International Classification of Diseases (ICD-10) is used by the DSPs to code deaths from 2004.¹³ Following the recommended TSCI codes by the U.S. Centers for Disease Control and Prevention (CDC), we used the following diagnosis codes to count TSCI deaths, including S12.0-S12.7, S13.0-S13.1, S13.4, S14.2, S14.0-S14.2, S15.1, S22.0, S22.1, S23.0-S23.1, S23.3, S24.0-S24.2, S32.0-S32.2, S33.0-S33.2, S33.5-S33.7, S34.0-S34.1, S34.3, S34.2, S34.4, T08, T09.3, T09.4, T91.1, and T91.3.

According to the classification of the underlying external causes of TSCI-induced deaths, we further classified TSCI mortality into three categories: (1) MVCs (V30-V78, V79 .4-V79.9, V81.1, V82.1, V83-V85, V86.0-V86.3, V20-V27, V28.3-V28.9, V29.4-V29.9, V12-V13, V14.3-V14.9, V19.4-V19.6, V02-V03, V04.1, V04.9, V09.2, V80.3-V80.5, V87.0-V87.8, V89.2, X82, Y03, Y32), (2) falls (W00-W19, X80, Y01, Y30), and (3) all others (remaining ICD-10 codes for all other causes).

Statistical analyses

The census population in 2010 was adopted as a reference population to calculate age-standardized mortality rates. Mortality rate ratio between 2006 and 2016 and 95% CIs were calculated via negative binomial regression to quantify mortality change over the year. Sex-, age-, location-, and cause-specific mortality rates were calculated, respectively. Considering extremely low mortality rates of many age groups when the classification with more age groups was adopted, we divided age into three subgroups: 0–44 years, 45–64, and 65 years and older. All statistical analyses were performed using Stata 12.1. All statistical tests were two-sided at a significant level of 0.05.

Results

From 2006 to 2016, a total of 2368 TSCI-induced deaths were reported. Age-adjusted TSCI mortality rate increased by 64% during the study time period, ranging from 0.19 to 0.34 per 100,000 population. The crude mortality was 0.31 per 100,000 population in 2016 (Table 1).

Table 1. Mortality rates (standard error) of traumatic spinal cord injury by location, sex, age group, and external cause in China, 2006–2016.

Variable	2006	2007	2008	2009	2010	2011	2012	2013	2014	2015	2016	% change in rate (95% CI)
Total	0.19 (0.02)	0.24 (0.02)	0.27 (0.02)	0.26 (0.02)	0.24 (0.02)	0.23 (0.02)	0.24 (0.02)	0.24 (0.02)	0.28 (0.02)	0.34 (0.02)	0.31 (0.02)	64 (34–100)
Location
Urban	0.18 (0.02)	0.24 (0.03)	0.26 (0.03)	0.23 (0.03)	0.20 (0.03)	0.18 (0.02)	0.20 (0.02)	0.20 (0.02)	0.25 (0.03)	0.32 (0.03)	0.31 (0.03)	75 (26–144)
Rural	0.20 (0.02)	0.24 (0.02)	0.27 (0.02)	0.28 (0.02)	0.28 (0.02)	0.27 (0.02)	0.27 (0.02)	0.28 (0.02)	0.31 (0.03)	0.37 (0.03)	0.32 (0.03)	59 (23–106)
Sex
Male	0.27 (0.03)	0.33 (0.03)	0.38 (0.03)	0.32 (0.03)	0.35 (0.03)	0.34 (0.03)	0.29 (0.03)	0.31 (0.03)	0.38 (0.03)	0.44 (0.03)	0.42 (0.03)	53 (20–95)
Female	0.11 (0.02)	0.15 (0.02)	0.15 (0.02)	0.19 (0.02)	0.14 (0.02)	0.12 (0.02)	0.19 (0.02)	0.17 (0.02)	0.18 (0.02)	0.23 (0.02)	0.23 (0.02)	107 (44–198)
Age group (years)
0–44	0.10 (0.01)	0.11 (0.01)	0.12 (0.01)	0.10 (0.01)	0.08 (0.01)	0.07 (0.01)	0.08 (0.01)	0.07 (0.01)	0.10 (0.01)	0.08 (0.01)	0.08 (0.01)	−21 (−47–19)
45–64	0.21 (0.04)	0.26 (0.04)	0.35 (0.04)	0.30 (0.04)	0.36 (0.04)	0.29 (0.04)	0.23 (0.03)	0.24 (0.03)	0.35 (0.04)	0.39 (0.04)	0.33 (0.04)	56 (5–133)
≥65	0.81 (0.12)	1.17 (0.14)	1.16 (0.13)	1.37 (0.15)	1.14 (0.13)	1.25 (0.13)	1.43 (0.14)	1.58 (0.14)	1.45 (0.13)	2.17 (0.16)	2.01 (0.15)	147 (80–237)
External cause
MVCs	0.03 (0.01)	0.04 (0.01)	0.05 (0.01)	0.05 (0.01)	0.05 (0.01)	0.03 (0.01)	0.04 (0.01)	0.04 (0.01)	0.05 (0.01)	0.05 (0.01)	0.04 (0.01)	29 (−24–118)
Falls	0.08 (0.01)	0.09 (0.01)	0.11 (0.01)	0.13 (0.01)	0.11 (0.01)	0.11 (0.01)	0.12 (0.01)	0.12 (0.01)	0.13 (0.01)	0.17 (0.01)	0.17 (0.01)	107 (54–177)
All others	0.08 (0.01)	0.11 (0.01)	0.11 (0.01)	0.08 (0.01)	0.08 (0.01)	0.09 (0.01)	0.08 (0.01)	0.09 (0.01)	0.10 (0.01)	0.12 (0.01)	0.10 (0.01)	31 (−6–83)

Notes: (1) Mortality rates for all and subgroup traumatic spinal cord injury (except for age groups) were age-standardized based on the population of China in 2010. (2) MVCs: Motor vehicle crashes. (3) % change in rate (95% CI) between 2006 and 2016 was calculated as “mortality rate ratio – 1” based on negative binomial regression model.

Males and rural residents had higher TSCI mortality rates than females and urban residents. Between 2006 and 2016, the age-adjusted TSCI mortality rate increased 53% (95% CI: 20%, 95%) for males, 107% (95% CI: 44%, 198%) for females, 75% (95% CI: 26%, 144%) in urban area, and 59% (95% CI: 23%, 106%) in rural area (Table 1, Fig. 1(A)).

Figure 1.

Mortality rates from traumatic spinal injury by location (urban/rural), sex, age group, and external cause in China, 2006–2016. (A) Mortality rates from traumatic spinal injury by location (urban/rural), sex and age group (China, 2006–2016). Both the TSCI mortalities of rural and urban residents showed a rising tendency from 2006 to 2016, but the urban residents showed a trough period from 2009 to 2014, compared to a relatively stable trend of the rural residents. TSCI mortality for males showed a completely different pattern of change comparing to females. Males were at least taking two-fold risk of dying of TSCI over time in the study period. Both 0–44 years old subgroup and 45–64 years old subgroup showed nearly unchanged in study period. 75+ years old subgroup showed noticeable increases at 2006–2016. (B) Mortality rates from traumatic spinal injury by location, sex, and external cause (China, 2006–2016). Compared to in urban, the motor vehicle crashes contributed more, though the general trend of TSCI mortality keeps similar. Contrast to females, males with a noticeable higher mortality were suffering higher proportion lethal factor caused by motor vehicle crashes. MVC: Motor vehicle crash. (C) Mortality rates from traumatic spinal injury by age group and external cause (China, 2006–2016). In the three age groups, falls began to contribute more and more to total TSCI mortality as age increased, while motor vehicle crashes contribute less and less. MVC: Motor vehicle crash.

TSCI mortality rates increased substantially as age got older. In comparison with insignificant change in the age group of 0–44 years, TSCI mortality increased 56% and 147% in age groups of 45–64 years and ≥65years (Table 1 and Fig. 1(A)).

Falls were the most common cause of TSCI mortality from 2006 to 2016, accounting for 45.4% of total mortality. Strikingly, only TSCI mortality from falls significantly increased by 107% (95% CI: 54%, 177%) between 2006 and 2016 (Table 1). The cause spectrum of TSCI somewhat differed across sex and place. Compared to males, TSCI mortality from motor vehicle crashes explained a much lower proportion in females (Fig. 1(B)).

The cause spectrum of TSCI mortality varied greatly across three age groups. As age increased, TSCI mortality from falls increased substantially; it became the dominating cause of TSCI mortality in the oldest age group in 2016 as its rate increased from 0.55 to 1.31 per 100,000 population (Table 2 and Fig. 1(C)).

Table 2. Mortality rates from traumatic spinal injury per 100,000 population (standard error) by external cause and age group in China, 2006–2016.

Cause	Age group (years)	2006	2007	2008	2009	2010	2011	2012	2013	2014	2015	2016
MVCs	0–44	0.02 (0.01)	0.03 (0.01)	0.04 (0.01)	0.03 (0.01)	0.03 (0.01)	0.02 (0.01)	0.03 (0.01)	0.03 (0.01)	0.03 (0.01)	0.03 (0.01)	0.03 (0.01)
	45–64	0.05 (0.02)	0.05 (0.02)	0.06 (0.02)	0.07 (0.02)	0.10 (0.02)	0.07 (0.01)	0.05 (0.01)	0.04 (0.01)	0.11 (0.02)	0.08 (0.02)	0.07 (0.02)
	≥ 65	0.03 (0.02)	0.06 (0.03)	0.08 (0.03)	0.09 (0.04)	0.06 (0.03)	0.05 (0.03)	0.09 (0.03)	0.08 (0.03)	0.10 (0.04)	0.10 (0.03)	0.07 (0.03)
Falls	0–44	0.03 (0.01)	0.02 (0.01)	0.03 (0.01)	0.03 (0.01)	0.03 (0.01)	0.02 (0.01)	0.02 (0.01)	0.02 (0.01)	0.04 (0.01)	0.02 (0.01)	0.02 (0.01)
	45–64	0.05 (0.02)	0.06 (0.02)	0.12 (0.03)	0.11 (0.02)	0.11 (0.02)	0.12 (0.02)	0.07 (0.02)	0.10 (0.02)	0.12 (0.02)	0.15 (0.03)	0.17 (0.03)
	≥ 65	0.55 (0.09)	0.67 (0.10)	0.72 (0.11)	0.94 (0.12)	0.76 (0.11)	0.70 (0.10)	0.96 (0.11)	0.90 (0.11)	0.87 (0.10)	1.35 (0.13)	1.31 (0.12)
All other	0–44	0.04 (0.01)	0.05 (0.01)	0.05 (0.01)	0.03 (0.01)	0.03 (0.01)	0.03 (0.01)	0.03 (0.01)	0.02 (0.01)	0.04 (0.01)	0.03 (0.01)	0.03 (0.01)
	45–64	0.11 (0.03)	0.15 (0.03)	0.17 (0.03)	0.12 (0.03)	0.15 (0.03)	0.10 (0.02)	0.11 (0.02)	0.09 (0.02)	0.12 (0.02)	0.17 (0.03)	0.10 (0.02)
	≥ 65	0.23 (0.06)	0.43 (0.08)	0.36 (0.07)	0.34 (0.07)	0.32 (0.07)	0.50 (0.08)	0.38 (0.07)	0.60 (0.09)	0.48 (0.08)	0.72 (0.09)	0.63 (0.08)

Note: MVCs: Motor vehicle crashes.

Discussion

This study has three major findings: (1) the overall age-standardized TSCI mortality rate increased from 0.19 per 100,000 population in 2006 to 0.31 per 100,000 population in 2016; (2) males, rural residents and age group≥65 years had comparatively higher TSCI mortality rate than females, urban residents and younger age groups; and (3) falls was the leading cause of TSCI mortality in China during the study time periods.

In our study, the crude TSCI mortality rates were 0.31 per 100,000 population in 2016, lower than other countries, for instance, the Europe¹ (0.67 per 100,000 population). Discrepancies in definitions of TSCI-induced deaths, study population, inclusion criteria, and data completeness might be the cause of data differences across countries. However, the real TSCI mortality may be substantially underestimated in this study because up to 46% of injury deaths on the death certificate did not have S- or T-code for nature of injury (N-code) between 2006 and 2016, which is far higher than that for the United States (0.6%).^10,11

Notably, the overall age-standardized TSCI mortality rate significantly increased by 64% between 2006 and 2016. Similar increases in the same time period were also observed for unintentional suffocation mortality among children aged 1–4 years.¹⁴ The recent increase likely reflects the threat from growing motorization over the country and much-lagged injury prevention. According to the official statistics, the number of motor vehicles increased from 37 million in 2006 to 186 million in 2016 in China.¹⁵ However, the China government has not paid enough attention to injury prevention and no specific agency is assigned to take charge of supervising and coordinating injuries prevention efforts, severely restricted the national investment in injury research.¹⁶ In the future, it is necessary to strengthen the intervention in this area, especially the intervention in road traffic accidents and falls. The previous study suggested that higher TSCI mortality among males might be linked to high likelihood of taking on high-risk occupations, such as aloft work employees, construction workers, truck drivers and others.¹⁷ Relatively higher TSCI mortality in a rural area can be partially explained poor first aid and hospital treatment compared to an urban area.¹⁸ The highest TSCI mortality is mainly because of declines in physical and cognitive functions due to aging and having chronic diseases.¹⁹

Cause-spectrum analysis displayed similar results to those from Austria,⁷ India,²⁰ and Turkey²¹; but our results differed from those from USA,²² Canada,²³ and Botswana,²⁴ where MVCs were the leading cause of TSCI deaths. These differences are probably due to the combined effects of various exposure likelihoods to specific injury risks, and differences in injury prevention efforts, first aid, and hospital treatment for TSCI patients.

Our findings underline the significance and urgency of prevention of TSCI, especially for the leading causes (e.g. falls and MVCs) and high-risk populations (e.g. old adults, males, and rural residents). As mentioned above, prevention efforts for TSCI, as well as for other injuries, have not been systematically implemented in the last few decades in China. The government of China must take the leading role in preventing TSCI. Evidence-based interventions for the leading injury causes and pre-hospital and hospital treatment should be implemented nationwide, including designing safe and sustainable road traffic systems, reducing exposure to risks through transport and land-use policies, reducing law violations, modifying residential environments to reduce risks for falls prevention.²⁵ If possible, cost-effective and highly feasible interventions should be included the national laws and regulations, such as child restraint or seatbelt use for motor vehicle passengers, and exercise, risk assessment, and multifactorial interventions for fall-induced injury among the elderly.

Limitations

Our study was mainly limited by the DSPs data. The change of DSPs reporting methods from paper-based reporting to Internet-based reporting in 2008 may lead to unexpected fluctuations in the TSCI mortality around 2008,¹¹ but we could not quantify its contribution due to lack of detailed data. Second, we cannot examine the contributions of important influencing factors to the observed increases in TSCI mortality because the DSPs does not collect the data of influencing factors, such as risk exposure factors, history of illness and injury, pre-hospital care and hospital emergency treatment, and relevant policy variables. Thus, we could not reasonably interpret the recent increase in TSCI mortality. These could be considered in future studies.

Conclusions

TSCI has remained a serious threat to the health of the Chinese population. The TSCI mortality rate was keeping a steady increase from 2006 to 2016 in China. Our study presents the national TSCI mortality in China for the first time. It would be very valuable for public health and intensive care medicine studies. Meanwhile, efficient precaution, response, and treatment interventions for TSCI, according to the World Health Organization, should be popularized and implemented in our health delivery system. This study will offer more evidence for critical care medicine to improve more rescuing measures for TSCI victims.

Disclaimer statements

Contributors None.

Funding This work was supported by the National Natural Science Foundation of China [grant number 81672174], the Natural Science Foundation of Hunan Province, China [grant number 2017JJ3507] and the Postdoctoral Science Foundation of Xiangya Hospital, Central South University, China [grant number 175817].

Conflict of interest None.