Epidemiology of idiopathic pulmonary fibrosis in northern Italy

Background Idiopathic pulmonary fibrosis (IPF) is the most common and severe form of idiopathic interstitial pneumonia. Despite its clinical relevance, few studies have examined the epidemiology of IPF and temporal variation in disease incidence and prevalence. Aim of the study was to investigate the prevalence, incidence and trends of IPF in Lombardy, a region with nearly 10 million inhabitants, during 2005-2010. Methods For the identification of IPF patients, we used healthcare administrative databases of Lombardy Healthcare System and adopted three algorithms: generic, broad and narrow case definition (GCD, BCD, NCD). IPF cases were identified according to diagnoses reported in inpatient and outpatient claims occurred during 2000-2010. We estimated age- and sex-adjusted annual prevalence and incidence rates from 2005 to 2010, thus allowing for a 5-year washout period. Results The mean annual incidence rate was estimated at 2.3 and 5.3 per 100,000 person-years using NCD and GCD, respectively. IPF incidence was higher among males, and increased with age. Trend remained stable over the years. The estimated annual prevalence rate was 35.5, 22.4, and 12.6 per 100,000 person-years using GCD, BCD and NCD, respectively, and increased with age. Moreover, we observed a positive trend over the years. Using BCD and NCD, prevalence was higher among males. Conclusions The results of this study, which is one of the largest population-based survey ever conducted according to strict criteria, indicated that prevalence of IPF increased across the years while incidence remained stable, thus suggesting that survival with IPF has improved.