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Injuries pose a significant public health challenge, accounting for 10.6% of the global burden of disease (1). The elderly population, due to their diminished ability to control their surroundings, are particularly vulnerable to injuries. In fact, injuries are the second leading cause of death among the elderly, resulting in substantial burden and economic loss for individuals, families, and society as a whole (2-3). Given the rapid growth of China’s aging population, these burdens are expected to escalate, underscoring the need for research on elderly injuries (4-5). Previous studies have shown a downward trend in injury-related mortality among Chinese elderly individuals (6). However, there is limited documentation on the long-term patterns of urban-rural disparities in injury mortality by age, period, and cohort (7). This study aims to examine the changing patterns of injury mortality among the elderly in China from 1987 to 2021, while also identifying the age-period-cohort effects on mortality changes. The findings of this study will provide valuable data for informing the development of injury intervention policies by relevant national agencies.
The injury mortality rates were derived from the death registration system of the National Health Commission in China, as previously described (8). Age-standardized mortality rates (ASMR) per 100,000 population were calculated using the direct method and the World Standard Population as a reference. To identify temporal trends in injury ASMR, a Joinpoint regression model was employed. Furthermore, the age-period-cohort model was used to assess the individual effects of age, period, and birth cohort on injury mortality rates in China (9).
The present study discovered a gradual decrease in injury-related mortality rates among the elderly population in China over a span of 35 years. It is noteworthy that older age, male gender, and residing in rural areas all contribute to a higher risk of injury-related death among the elderly. Although there is a contrasting trend in injury mortality rates between urban and rural areas for the elderly, the disparities in period effects and cohort effects are minimal.
Figure 1 shows long-term trends in ASMR for injury in China’s urban and rural populations by sex from 1987 to 2021. The ASMR from injuries among the elderly largely maintained a gentle decline from 1987 to 2002, except for a rebound period (1996–1998) in rural males. From 2002 to 2006, the ASMR for urban elderly males and females experienced two significant fluctuations, while the rate for rural elderly declined more rapidly. Subsequently, the ASMR for urban and rural elderly exhibited a slight increase. There was a fluctuation characterized by an initial decrease followed by an increase around 2010, and the rate has since remained broadly stable.
Figure 1.Trends in age-specific standardized mortality rates of injury among the elderly in urban and rural China by sex: 1987–2021.
The joinpoint results are presented in Table 1. Overall, there was a slight decrease in injury ASMR in both urban and rural areas, although the substage trends varied. In urban areas, ASMR showed a relatively marked decline from 1987–2008, then a slight rebound from 2008–2021. In contrast, ASMR in rural areas showed a slight decline from 1987–2006, and finally a nearly flat rebound from 2006–2021. In addition, all annual percent changes between sexes indicated a slight urban-rural disparity.
Residence Mortality rate† (per 100,000) Entire range§ Segment 1 Segment 2 1987 2021 AAPC (%) 95% CI Period APC (%) 95% CI Period APC (%) 95% CI Urban Total 22.28 11.84 −1.5* (−2.6, −0.6) 1987−2008 −3.2* (−4.1, −2.3) 2008−2021 1.3 (−0.7, 3.3) Male 22.47 14.06 −1.0* (−1.9, −0.0) 1987−2008 −2.6* (−3.6, −1.6) 2008−2021 1.7 (−0.3, 3.8) Female 22.08 9.77 −1.9* (−2.8, −1.0) 1987−2009 −3.4* (−4.3, −2.6) 2009−2021 1.0 (−1.2, 3.2) Rural Total 21.78 17.32 −0.9* (−1.5, −0.4) 1987−2006 −1.7* (−2.2, −0.9) 2006−2021 −0.1 (−1.1, 0.8) Male 25.08 21.09 −0.7* (−1.2, −0.3) 1987−2005 −1.5* (−2.1, −0.8) 2005−2021 0.1 (−0.7, 0.9) Female 18.76 13.70 −1.2* (−1.6, −0.7) 1987−2006 −1.9* (−2.4, −1.4) 2006−2021 −0.2 (−1.0, 0.5) Abbreviation: APC=annual percent change; AAPC=average annual percent change; CI=confidence interval.
* P<0.05.
† Standardization employed is based on the world standard population from the World Health Organization.
§ The time frame considered ranges from 1987 to 2021.Table 1. Joinpoint analysis of age-standardized mortality rates from injury in urban and rural areas.
Figure 2 depicts the net drift and local drift of mortality rates for injury. Both net drift and local drift were calculated separately in the APC model. Net drift represents the time-trend effect on the entire population, while local drift indicates the log-linear trend specific to each age group. In both rural and urban areas of China, there was a similar net drift pattern, with a significant decrease in injury mortality rates over the study period. The decline in mortality rates was more pronounced for females compared to males, both in urban areas (females: −2.12% vs. males: −1.12%) and rural areas (females: −1.33% vs. males: −0.77%). Notably, the local drift curves in urban and rural areas exhibited contrasting patterns. In urban areas, the decline in injury-related mortality became increasingly pronounced with age among the elderly, whereas in rural areas, the opposite trend was observed.
Figure 2.Local drift with net drift values for injury mortality rates and sex disparity by area in China from 1987 to 2021. (A) Net and local drifts in urban areas; (B) net and local drifts in rural areas.
Figure 3 shows the estimates of age, period, and cohort effects on mortality rates for injuries. Age effect patterns are consistent across sexes, as well as urban and rural areas. The older the age group among the elderly, the higher the mortality. The mortality rate for males is generally higher than that for females, but this sex difference is gradually narrowing. However, the mortality rate for rural elderly individuals is consistently higher than that for the corresponding urban group. Period effects in urban and rural areas are largely consistent, except for the period from 2002–2007. Additionally, the earlier the birth cohort, the higher the mortality rate, whether in urban or rural areas. For the birth cohorts between 1902 and 1927, the urban areas consistently have a higher mortality rate compared to rural areas.
Figure 3.The effects of age, period, and cohort on age-standardized mortality rates due to injury among the elderly in China from 1987 to 2021. (A) Age effects in urban areas; (B) age effects in rural areas; (C) period effects in urban areas; (D) period effects in rural areas; (E) cohort effects in urban areas; (F) cohort effects in rural areas.
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