Idiopathic pulmonary fibrosis--a systematic review on methodology for the collection of epidemiological data.

Background: Recent studies suggest that the incidence of idiopathic pulmonary fibrosis (IPF) is rising. Accurate epidemiological data on IPF, however, are sparse and the results of previous studies are contradictory. This study was undertaken to gain insight into the various methods used in the epidemiological research of IPF, and to get accurate and comparable data on these different methodologies.

Methods: A systematic database search was performed in order to identify all epidemiological studies on IPF after the previous guidelines for diagnosis and treatment were published in 2000. Medline (via Pubmed), Science Sitation Index (via Web of Science) and Embase databases were searched for original epidemiological articles published in English in international peer-reviewed journals starting from 2001. After pre-screening and a full-text review, 13 articles were accepted for data abstraction.

Results: Three different methodologies of epidemiological studies were most commonly used, namely: (1) national registry databases, (2) questionnaire-based studies, and (3) analysis of the health care system's own registry databases. The overall prevalence and incidence of IPF varied in these studies between 0.5-27.9/100,000 and 0.22-8.8/100,000, respectively. According to four studies the mortality and incidence of IPF are rising.

Conclusions: We conclude that there are numerous ways to execute epidemiological research in the field of IPF. This review offers the possibility to compare the different methodologies that have been used, and this information could form a basis for future studies investigating the prevalence and incidence of IPF.