Incidence and prevalence of idiopathic pulmonary fibrosis: review of the literature.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrosing interstitial pneumonia of unknown aetiology. It is a rare disease, and its incidence and prevalence are not clear. Therefore, we sought to review the published evidence on the global epidemiology of IPF. A comprehensive review of English language literature was performed by searching Medline and EMBASE for studies on IPF epidemiology published between January 1990 and August 2011. Studies providing quantitative data on IPF incidence and/or prevalence were identified and key data collected. 15 studies reporting on the incidence and/or prevalence of IPF were identified and summarised. IPF prevalence estimates in the USA varied between 14 and 27.9 cases per 100,000 population using narrow case definitions, and 42.7 and 63 per 100,000 population using broad case definitions. In Europe, IPF prevalence ranged from 1.25 to 23.4 cases per 100,000 population. The annual incidence of IPF in the USA was estimated at 6.8-8.8 per 100,000 population using narrow case definitions and 16.3-17.4 per 100,000 population using broad case definitions. In Europe, the annual incidence ranged between 0.22 and 7.4 per 100,000 population. IPF prevalence and incidence increase with age, are higher among males and appear to be on the increase in recent years. IPF is an orphan disease that affects a potentially increasing number of people in Europe and the USA. The observed variability in IPF incidence and prevalence may be explained by the differences in diagnostic criteria used, case definition, study population and study design.