Incidence and prevalence of idiopathic pulmonary fibrosis: a systematic literature review and meta-analysis.

Background: Idiopathic pulmonary fibrosis (IPF) is a progressive and serious lung disease with a poor prognosis and severe clinical and humanistic burden. This systematic literature review and meta-analysis aimed to summarize and quantify the data on IPF incidence and prevalence among adults within the general population and to compare regional differences.

Methods: Comprehensive searches of MEDLINE^®, Embase, and the Cochrane Database of Systematic Reviews were conducted to capture available studies published in English from January 1, 2000, to November 7, 2023, that reported on the incidence or prevalence of IPF. Pooled weighted-mean incidence and prevalence estimates were calculated from studies reporting adequate epidemiological data using a DerSimonian-and-Laird random-effects model.

Results: Of 4,077 records identified, 26 studies were included in the meta-analysis (17 reported both prevalence and incidence, 6 reported incidence only, 3 reported prevalence only). Most studies were retrospective, with study periods ranging from 1984 to 2021. Pooled global incidence per 100,000 (95% confidence interval) was 5.8 (4.8, 6.8; 23 studies). Pooled incidence in Asia was 4.4 (1.6, 7.2; 5 studies), 5.1 (3.9, 6.3; 13 studies) in Europe, and 9.0 (6.9, 11.1; 5 studies) in North America. Pooled prevalence (per 100,000) was 17.7 (14.0, 21.5; 20 studies) globally, 14.8 (7.1, 22.6; 6 studies) in Asia, 14.6 (9.4, 19.7; 9 studies) in Europe, and 27.2 (21.0, 33.4; 6 studies) in North America.

Conclusion: This analysis confirms that IPF is a rare condition globally, but substantial heterogeneity exists across studies. Incidence and prevalence were notably high in North America compared with Europe and Asia. This finding may be explained by the use of selective source populations in North American studies, in contrast to the more general populations used in European or Asian studies. Additional contributing factors include variations in case identification algorithms, differences in diagnostic definitions and regional differences in occupational and environmental exposures. While recent multi-societal guidelines have advanced the standardization of the IPF diagnostic process, variability in clinical practice remains a challenge that affects comparisons of incidence and prevalence across regions and over time.