Interstitial Lung Disease Epidemiology in the Second Millennium: A Narrative Review

Current epidemiological data about interstitial lung disease (ILD) are still poor. The principal cause of the discordant data is associated with a heterogeneous group of respiratory diseases that includes a large number, about 200 families, with low frequency, distinct and sometimes unknown etiology, and different progression. Furthermore, epidemiological data are limited. Scope of the narrative review is to report ILD incidence and prevalence in Registries from different Countries in the second millennium. We identified 16 ILD Registries (14 prospective and 2 retrospective) from major Countries in Europe (n = 10), Asia (n = 7), North America (n =2) and Oceania (n = 1). Significant discrepancies in ILD and ILD subtypes prevalence and incidence among countries are reported in Registries. These discrepancies could be determined by different ethnicities and socio-economic conditions as well as by updates in disease diagnosis and classification. ILD epidemiological Registries are progressively ameliorating through a better adherence to updated Guidelines and Classification codes. An accurate and definite compilation of ILD epidemiological Registries will be useful for a more precise monitoring of disease progression and treatment.