Global trends and inequalities in environmental risk-attributable chronic obstructive pulmonary disease mortality among adults aged 80+ years, 1990-2021: an analysis of the Global Burden of Disease Study 2021.

Background: While the aging global population faces a rising chronic obstructive pulmonary disease (COPD) mortality burden, comprehensive assessments of this burden concerning multiple environmental risks and socioeconomic inequalities among the oldest-old (aged ≥80 years) remain limited. This study aims to comprehensively assess the burden of environmental risk-attributable COPD mortality, its temporal trends, and socioeconomic inequalities among the global population aged ≥80 years. Methods: Data from the Global Burden of Disease (GBD) Study 2021 were used to analyse COPD deaths and age-specific mortality rates attributable to eight environmental risk factors among adults aged 80 years and older from 1990 to 2021. Mortality estimates were derived from multiple GBD data sources, including household surveys, censuses, and vital registration systems. We examined mortality patterns and trends at the global, regional, and national levels. Temporal trends in age-specific mortality rates were assessed using Joinpoint regression, and Socio-demographic Index (SDI) related inequalities across 204 countries were evaluated using the slope index of inequality (SII) and relative concentration index (RCI). Results: In 2021, the leading environmental risk factors for age-specific COPD mortality rates were smoking {351.85 per 100,000 population [95% uncertainty interval (UI): 268.79-433.10]}, ambient particulate matter pollution [241.60 (175.22-299.69) per 100,000 population], and household air pollution from solid fuels (HAP) [157.27 (83.42-292.74) per 100,000 population]. The leading contributor to male COPD mortality was smoking [717.70 (555.94-871.14) per 100,000] and ambient particulate matter pollution [335.99 (245.85-411.01) per 100,000 population], whereas female mortality was primarily driven by ambient particulate matter pollution [181.00 (123.04-234.92) per 100,000 population] and HAP [141.30 (76.19-250.28) per 100,000 population]. From 1990 to 2021, COPD mortality rates attributable to HAP showed the largest reduction [percentage change: -72% (-83% to -53%)]. Joinpoint regression revealed temporal patterns. Smoking attributable mortality increased until 1998, then sustained a decline. Ambient particulate matter pollution attributable mortality rose until 2014 before decreasing. Ambient ozone attributable mortality followed a fluctuating pattern. High temperature was the only factor among the eight assessed with a statistically significant, overall increasing trend throughout 1990-2021 {annual percent change: 1.49% [95% confidence interval (CI): 0.98-2.00]}. In terms of health inequalities, HAP demonstrated the highest degree of socio-demographic inequality in 2021 [RCI: -0.404 (-0.474 to -0.334); SII: -545.59 (-637.30 to -453.89) per 100,000 population], with the relative inequality increasingly concentrated in lower-SDI countries. For ambient particulate matter pollution, absolute inequality shifted increasingly toward disadvantaged settings. Notably, both absolute and relative inequalities in ozone-attributable COPD mortality increased from 1990 to 2021, with mortality disproportionately concentrated in lower-SDI countries. Conclusions: These findings provide a critical evidence base for formulating integrated public health strategies aimed at mitigating burdens of environmental risk-attributable COPD mortality among adults aged 80 years and older. Such strategies entail prioritizing clean energy, clean cooking technologies, and ozone control in lower-SDI regions, along with reinforcing tobacco and climate-related actions globally.