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Tuberculosis (TB), caused by Mycobacterium tuberculosis (1), globally has a mean incidence rate of approximately 106.7 per 100,000 (2). It also emerges as one of the primary causes of death across the world (3). Despite longstanding preventive and control measures for TB in China (4), the nation ranks third-highest in TB incidence among the 30 countries with the highest TB burden (2). The urgent necessity to explore the disease’s epidemiology and trajectory caters to shortcomings in the breadth of studies assessing long-range trends of respiratory TB mortality in China across geographical areas and genders. Our study seeks to furnish an all-encompassing scrutiny of temporal patterns to aid policymakers in responsibly devising optimization strategies. Data were derived from the National Health Commission (1954–2013, Ministry of Health; 2013–2018, National Health and Family Planning Commission), categorizing deaths in line with the International Classification of Disease 9th revision (ICD-9) and ICD-10 standard — the former being applied until 2002, followed by ICD-10. Utilizing National Health Commission data, via Joinpoint regression analysis and age-period-cohort (APC) models, we investigated the respiratory TB annual mortality rate estimates spanning 1987 to 2021. The Joinpoint regression model, endorsing a timeline trend evaluation method, facilitates a segmented regression formulation based on disease distribution time characteristics — thereby facilitating a more detailed appraisal of varying time spans within the aggregate respiratory TB mortality trend. To tackle the linear functional interrelationship problem between age effects, period effects, and cohort effects, APC models were deployed. Our outcomes indicate a persistent decline in mortality rates over time, particularly in rural zones. However, the gender divide has expanded over the years. For further abatement of respiratory TB mortality rates and to align with global control objectives, focused interventions should strategically prioritize key clusters like men and the elderly.
Table 1 illustrates the longitudinal trends of respiratory TB in China, disaggregated by region and gender. The data spans from 1987 to 2021 and reveals a compelling decrease in both crude and age-specific mortality rates across all specific populations. Higher mortality rates were observed in males versus females and in rural regions as compared to metropolitan ones. However, the disparity between urban and rural areas progressively lessened over time. In 1987, the age-specific mortality rate (ASMR) associated with respiratory TB in urban areas was 12.22 per 100,000, with a breakdown of 16.27 for males and 7.69 for females. Up to the year 2021, the rates witnessed a commendable average annual decline of −7.2%, −6.8%, and −8.3% respectively. As for rural regions, the ASMR stood at 25.16 per 100,000 in 1987 with notable rates of 33.06 per 100,000 for males and 18.41 per 100,000 for females. By 2021, the average annual decline had reached −8.3%, −7.9%, and −9.9%, respectively. Strikingly, despite initiating with higher respiratory TB mortality rates than their urban counterparts, rural regions demonstrated a faster rate of decline.
Tuberculosis Mortality rate
(per 100,000)Total study period§ Period 1 Period 2 Period 3 Period 4 1987 2021 AAPC (%) 95% CI Years APC (%) Years APC (%) Years APC (%) Years APC (%) Crude mortality Urban areas Total 9.83 1.25 −5.5* (−8.5, −2.4) 1987–2000 −9.0* 2000–2003 12.8 2003–2006 −19.2 2006–2021 −2.7* Male 12.88 1.93 −5.3* (−6.4, −4.2) 1987–1997 −8.5* 1997–2021 −3.9* – – – – Female 6.58 0.56 −6.8* (−10.4, −3.0) 1987–2000 −11.1* 2000–2003 18.6 2003–2006 −25.5 2006–2021 −3.3* Rural areas Total 20.21 1.65 −6.6* (−8.4, −4.8) 1987–2001 −6.9* 2001–2005 −21.1* 2005–2021 −2.4* – – Male 25.07 2.52 −6.1* (−7.6, −4.6) 1987–2001 −6.9* 2001–2005 −18.6* 2005–2021 −1.9* – – Female 15.17 0.74 −8.2* (−10.2, −6.2) 1987–2001 −7.4* 2001–2008 −19.9* 2008–2016 2.9 2016–2021 −9.7* Age-standardized mortality† Urban areas Total 12.22 0.78 −7.2* (−10.9, −3.3) 1987–2000 −10.9* 2000–2003 18.5 2003–2006 −26.6 2006–2021 −4.1* Male 16.27 1.29 −6.8* (−10.4, −3.2) 1987–2000 −10.0* 2000–2003 14.7 2003–2006 −23.9 2006–2021 −4.1* Female 7.69 0.32 −8.3* (−13.1, −3.3) 1987–2000 −12.6* 2000–2003 24.7 2003–2006 −31.4 2006–2021 −4.8* Rural areas Total 25.16 1.05 −8.3* (−9.9, −6.6) 1987–2001 −7.7* 2001–2006 −20.1* 2006–2021 −4.6* – – Male 33.06 1.71 −7.9* (−10.0, −5.7) 1987–2002 −8.0* 2002–2005 −23.9* 2005–2021 −4.4* – – Female 18.41 0.44 −9.9* (−12.2, −7.4) 1987–2001 −7.8* 2001–2008 −22.0* 2008–2016 0.5 2016–2021 −12.8* Note: “–” means no joinpoints identified.
Abbreviation: APC=annual percent change; AAPC=average annual percent change; CI=confidence interval.
* Significantly different from zero (P<0.05).
† Standardized to the WHO world standard population.
§ Years 1987 to 2021.Table 1. Joinpoint analysis of crude and age-standardized mortality rates from tuberculosis in urban and rural areas.
Figure 1 depicts the net-drift and local-drift of respiratory TB. net-drift refers to the average annual trend for the entire population throughout the research period, while local-drift signifies the average trend within specific age groups. The Net-drift demonstrated a significant reduction in respiratory TB mortality in both rural and urban areas of China for the time from 1987 to 2021. The mortality rate decreased by 9.21% [95% confidence interval (CI): −9.77% to −8.64%] in rural regions and 6.32% (95% CI: −6.82% to −5.81%) in urban areas. A more pronounced annual shift in overall respiratory TB mortality was noted among females compared to males. The Net-drifts for urban men and women were −5.81% (95% CI: −6.43% to −5.19%) and −7.76% (95% CI: −8.33% to −7.18%), respectively. The figures for rural men and women were −8.27% (95% CI: −8.83% to −7.70%) and −10.90% (95% CI: −11.58% to −10.22%), respectively. The local-drift showed a general enhancement in China’s respiratory TB mortality control, particularly noteworthy among women aged 30–60. However, progression in reducing respiratory TB fatalities was relatively slight for the age groups 10–20 and those 70 years and over, although it remained generally below the 0 lines.
Figure 1.Local-drift and net-drift for tuberculosis mortality and urban-rural difference by sex in China from 1987 to 2021. (A) Urban area; (B) Rural area.
Figure 2 illustrates the influence of age, period, and cohort on the mortality rate of respiratory TB. The age-related effect revealed significant disparities between urban and rural areas. Mortality amongst urban males increased before declining with age, peaking at 75. Conversely, the mortality rate for women steadily decreased after reaching its apex at approximately age 20. For rural men and women, a consistent decline in the rates became apparent from age 25 onwards. Period effects demonstrated similar trends between rural and urban populations but showed a quicker decrease in rural areas than in metropolitan ones. Furthermore, the situation improved remarkably for females. Prior to 2003, females had higher rates than males, however, this pattern inverted post-2003, indicative of the significant success of respiratory TB control, particularly amongst rural females. The cohort effect exhibited similar patterns across both genders and locations. From 1900 to 1955, the mortality rate ratio of Chinese birth cohorts saw a significant reduction, especially in rural regions. As for the post-1960 birth cohorts, this decline has somewhat decelerated, yet continues to trend downward. The rural female birth cohort experienced the most substantial improvement.
Figure 2.Parameter estimates of age, period, and cohort effects on tuberculosis mortality rate in urban-rural 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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