National and provincial burden of interstitial lung disease mortality in China, 2013–2021: a nationwide analysis of trends and underlying cause of death

The national and provincial epidemiological characteristics of interstitial lung disease (ILD) mortality remain unknown in China. To assess ILD mortality trends, causes, and regional disparities in China (2013–2021). All death cases with ILD coded as the underlying cause or cause in any part of the cause of death chain from the National Mortality Surveillance System (NMSS) during 2013–2021 were included. Annual crude and age-standardized mortality rates (ASMR) were estimated by gender, age group, urban/rural, and province from 2013 to 2021. Joinpoint regression models were applied to calculate the average annual percentage change (AAPC) and corresponding 95% confidence intervals (CIs) in China during the study period. The distribution of different ILD subtypes with the broad category of ILD as the underlying cause of death was analyzed. We also analyzed the ranking of underlying cause of death for all ILD-associated deaths. In 2021, the ASMR for ILD in China was 2.90/100,000 (95%CI: 2.84, 2.96), decreasing by 45.18% (AAPC: -7.65, 95% CI: -13.46, -1.45) compared with 2013 (5.29/100,000; 95%CI: 5.19, 5.39). Eighty percent of ILD deaths in China were 60 years or older. Nationally, ILD ASMR declined consistently across sexes, urban-rural divides, and eastern, central, and western regions during the study period. Among those who died with ILD in 2021, the top four underlying causes of death were other respiratory diseases (J98) (11.54%), sequelae of cerebrovascular disease (I69) (10.18%), other ILD (J84) (7.61%), and malignant neoplasm of bronchus and lung (C34) (7.01%). The mortality burden of ILD stayed relatively high in males, those in economically developed regions, and the elderly. We recommend enhancing disease activity monitoring in high-risk groups or patients with specific ILD subtypes to lower mortality risk.