Epidemiology of interstitial lung diseases in Asia

The epidemiology of interstitial lung diseases (ILDs) in Asia has gained increasing attention with the emergence of new population- based datasets and national registries. Current evidence demonstrates that the burden and subtype distribution of ILDs vary considerably across regions, reflecting differences in genetic susceptibility, environmental or occupational exposure, and healthcare infrastructure. IPF is the commonest subtype of ILD in Europe and North America. However, Asian epidemiologic data suggest a more heterogeneous distribution, including hypersensitivity pneumonitis and sarcoidosis across the Indian subcontinent, and connective tissue disease-associated ILD among East Asians, comprising substantial disease burden. Although these studies provide important insights, they also reveal substantial methodological heterogeneity, including variable diagnostic code-based disease ascertainment, inconsistent case definitions, and limited availability of longitudinal follow-up. Environmental risk factors unique to Asian settings remain poorly characterized, and molecular or genomic data are sparse despite the fact that regional differences in disease phenotype and severity are evident. This review synthesizes and critically appraises the available epidemiological evidence on major ILD subtypes across Asia, summarizes emerging trends, and highlights key sources of variability in reported incidence and prevalence.