Background
As a major public health problem, injury is responsible for a large proportion of the global disease burden. In 2015, about 5 million deaths were attributable to injury, which was equivalent to about 9% of total global mortality [
1]. The pattern of injury mortality varies significantly across countries and areas along with the difference in essential demographic characteristics, economy income, customs, and lifestyle, etc. [
2‐
8].
China has experienced dramatic changes in lifestyle, environment and economy (Gross Domestic Product (GDP) increased about 7% per year since 2012). All these changes have substantially resulted in changes in the injury mortality pattern [
5,
6]. Injury-related mortality has decreased from 1990 to 2010, however the mortality of road-traffic injury is increasing in China. In 2010, the age-standardized injury mortality was 57/100,000 in China, with the leading causes of road-traffic injury, drowning, suicide and fall [
5,
6]. The injury spectrums were different among provinces and areas according to the Disease Surveillance Points (DSP) system in China [
7,
8]. The leading causes of injury death cis-position was suicide, road-traffic injury, drowning, falls in rural area, whereas, it was road-traffic injury, falls, suicide and drowning in urban areas of Hubei Province, China [
7].
Guangdong Province, located in southern China, has a population of more than 100 million, making up 1/14 of the counry’s total population. The GDP of Guangdong Province is the first in the country. The injury was the fourth leading cause of deaths in Guangdong Province, which has drawn attention in recent years [
9]. Along with the rapid social developments, the pattern of injury mortality might have changed greatly. However, the mortality patterns of injury in Guangdong Province remain unclear.
In the past 10 years, the number of surveillance areas in Guangdong province has gradually increased, with improved data quality as more resources have been allocated on the prevention and control of injuries. Therefore, we conducted this study using death data from the population-based mortality surveillance system to describe the epidemiological characteristics of injury mortality in Guangdong Province, China in 2015, and estimate the disease burden of injury in the whole province.
Methods
Data collection
The mortality data were collected through the population-based mortality surveillance system in Guangdong Province, China. This system was maintained by the Guangdong Provincial Center for Disease Control and Prevention (CDC). All deaths were reported and re-checked according to a quality control protocol as a part of routine processing operation at provincial, municipal and district levels in Guangdong Province. In 2015, Guangdong Provincial CDC collected the mortality data from 28 areas, 14 of which, including nine urban areas and five rural areas, were used in this analysis since they had a relatively higher data quality, with crude annual overall mortality rates higher than 5%.
Classification of injury deaths
Injury causes were defined using the International Classification of Diseases, Tenth Revision (ICD–10). The codes identified the four major unintentional injury causes of death: transport injuries (V01-V04, V06, V09-V80, V87, V89 and V99), accidental poisonings (X40-X49), accidental falls (W00-W19), drowning (W65-W74), as well as other unintentional causes. In addition, the codes also identified two major intentional injury causes of death: self-inflicted injuries (X60-X84, Y87.0) and interpersonal violence (X85-Y09, and Y87.1), as well as legally interventions, war operations and other intentional causes [
2,
10‐
12].
Population
The number of people of all age groups (0, 1–4, 5–9, 10–14,... 85+), gender and areas (urban and rural) in the population were deduced according to the overall populations of Guangdong Province in 2015 issued by the Bureau of Statistics of Guangdong. The statistics of fifth and sixth population census and the age distribution of population released by the Center of Statistics and Information of National Health and Family Planning Commission.
Data quality
The population size of the 14 areas was 9,959,716 (5,034,197 males and 4,925,519 females), accounting for 11.25% of the total population in Guangdong Province in 2015. Of them, 7,085,724 were from urban areas and 2,873,992 were from rural areas. In 2015, an under-reporting survey was conducted to investigate the completeness of the mortality data. Under-reporting rate is based on the total number of cases (M) in the surveillance and the estimated overall death toll (N) (under-reporting rate = (N-M) × 100%/N) [
13]. The mortality rates were calculated according to the result of the under-reporting survey in 2015:
Adjusted mortality rate = crude mortality rate/ (1- under-reporting rate).
Data analysis
We checked and evaluated data quality according to the under-reporting survey data quality control protocol and criteria. We combined and aggregated the data of 14 areas for the analysis. The mortality was adjusted according to the under-reporting rate. We calculated both crude rates (CR) and age-standardized rates (ASR) with the Chinese standard population and world standard population as standard population [
14].
We estimated the numbers of injury deaths, age and sex-specific mortality for all the injury types from the 14 surveillance areas in Guangdong. For the most common types of injury (road-traffic injury, falls, drowning, suicide, poisoning, violence, and other types), the estimated numbers of injury deaths were stratified by urban/rural areas.
Discussion
In the current study, we provided a comprehensive description of the injury mortality pattern using the latest and most representative data in Guangdong Province, China. The results showed that injury is an important public health problem in Guangdong Province. We summarized the epidemiological characteristics as follows: 1) Crude and age-adjusted injury mortality rates were significantly higher in rural areas than in urban areas, and higher in males than in females. 2) The leading cause of injury deaths was unintentional injuries, but suicide should not be ignored. 3) The mortality spectrum of unintentional injuries was different between rural and urban areas, males and females.
The injury mortality rate in Guangdong Province was lower than that of the global average and national average [
11,
15]. The followings may explain the results: there were abundant health resources in Guangdong Province with higher economy than the national average. In addition, there were sufficient emergency medical services and higher awareness of disease prevention in Guangdong Province.
In comparison to the Third National Retrospective Survey on Causes of Death in 2004–2005 [
16,
17], the injury mortality rate had decreased in Guangdong Province, with similar tendency to that of the national and other areas [
5,
7,
11,
18]. In the past decade, the declining trend of injury mortality may be due to the enforcement of the Traffic Safety Law which provides punishments for both “driving while intoxicated” and “driving after drinking alcohol” in China [
19‐
23].
The mortality spectrum of injuries in Guangdong Province was similar to the global and national situation [
11,
15], the majority of injury deaths was due to unintentional injuries, which constituted 83.93% of all injury deaths in Guangdong Province in 2015. At the same time, suicide could not be ignored, which consisted of 12.67% of all injury deaths. Compared with the global and national suicide mortality rates, the mortality rate of suicide was relatively lower in Guangdong Province [
11,
15,
24,
25]. However, homicide was one of the leading causes of injury deaths in other countries [
4,
26,
27]. In comparison to the 3rd NRSCD, the first leading causes of injury changed from road traffic accidents to falls, suicide became third leading cause of injury. Therefore, we should pay more attention to falls while Guangdong Province enters an aging society.
The top four leading causes of injury deaths (falls, road traffic accidents, suicide, drowning) in Guangdong Province were different from the whole world (road traffic accidents, suicide, falls and violence) [
15], the whole country (road-traffic accidents, falls, drowning, accidental poisoning) [
11,
15,
28] and South Africa (homicide, road traffic injuries, suicide and fires, burns and hot substances) [
4]. One important underlying reason for the high falls mortality rate was aging, we suggest that Guangdong Province should implement more appropriate strategies (the need for improvement of environmental conditions in communities and home) to prevent the occurrence of falls.
In Guangdong Province, crude and age-adjusted injury mortality rates in 2015 were higher in rural areas and in males. It is consistent with other reports in China [
7,
29‐
31], and developed countries, such as Australia, Canada [
32,
33] and Norway [
34]. Generally, individuals in rural areas, are more likely to engage in higher risk work than in urban areas, males were also in higher risk-taking behaviors than females. Limited medical resources and lower levels of health care may also explain the above results. More government-funded health resources and services should be allocated to the injury control in rural areas in Guangdong Province to reduce these apparent urban and rural inequalities.
The injuries mortality rates of road traffic accidents, drowning and accidental poisoning in rural areas were twice of that in urban areas. Similar findings had been reported elsewhere in China [
7,
29,
30]. The mortality rate in males was three times higher than that in females in both urban and rural areas. The falls-related injury mortality rates higher in females, whereas, the injury mortality rates resulting from road traffic accidents, drowning and accidental poisoning were higher in males.
These results will serve as a baseline for future assessment of the overall effectiveness of the injury control efforts in Guangdong Province and will provide insights into the areas of greatest need for prioritization.
A few limitations should be noted. Firstly, the current study was based on the surveillance data in a single year, the injury mortality rates lack longitudinal applicability. Secondly, along with the urbanization, development is evident in the rural areas, including the extension of health services and the change of production structure. Growth and development in the urban and rural areas of Guangdong Province are likely to influence the rate and type of injuries over time. Thirdly, the data from the 14 surveillance areas were composed of nine urban areas and five rural areas, with more population in urban areas than in rural areas.
Acknowledgements
We sincerely thank all staffs of 14 surveilled areas in Guangdong province who have made a great contribution to the study, especially on data collection, supplements, auditing, and database management.