Household energy, tuberculosis, and poverty: which national signals track the rising global burden of interstitial lung disease? A 204-country longitudinal study, 2000–2021, with projections to 2050

Rationale. Global studies show that interstitial lung disease (ILD) and pulmonary sarcoidosis are increasing and unequally distributed, but potentially modifiable national correlates of this burden remain poorly characterized. Our aim is to identify potentially modifiable national factors associated with ILD burden and estimate burden trajectories to 2050. Methods. We linked GBD 2021 estimates with World Bank and WHO indicators for 204 countries, 2000–2021, and directly standardized reconstructed both-sex outcomes. We fitted country and year fixed-effects models with country-clustered standard errors and policy-relevant lags, then projected empirically shrunk country trends to 2030, 2040, and 2050. Results. Four potentially modifiable national factors were associated with ILD burden. Higher tuberculosis incidence (+ 68/100,000) was associated with a 1.00% higher DALY rate at 3 years (95% CI, 0.48–1.53%); greater clean-cooking access (+ 4 percentage points) with a 1.00% lower rate at 10 years (0.32–1.68% lower); higher societal poverty (+ 4.1 percentage points) with a 1.52% higher rate at 5 years (0.04–3.04%); and greater universal health coverage (+ 5.1 points) with a 1.90% lower rate at 1 year (0.32–3.46% lower). Tuberculosis associations reflected partial structural confounding rather than an independent causal effect. Global DALYs rose from 2.09 to 4.04 million (2000–2021), reaching a projected 9.53 million by 2050 under continuation of 2010–2021 trends. Conclusions. Tuberculosis burden, household energy, poverty, and health-service coverage were the principal modifiable national correlates of ILD burden. Their distinct mechanisms support an integrated agenda of infectious-disease control, clean energy, social protection, and equitable respiratory care, though ecological associations do not establish intervention effects.