Chest
Volume 137, Issue 1, January 2010, Pages 129-137
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Original Research
Idiopathic Pulmonary Fibrosis
Incidence, Prevalence, and Clinical Course of Idiopathic Pulmonary Fibrosis: A Population-Based Study

https://doi.org/10.1378/chest.09-1002Get rights and content

Background

Limited data exist regarding the population-based epidemiology of idiopathic pulmonary fibrosis (IPF). The objective of the study was to describe the trends in the incidence, prevalence, and clinical course of IPF in the community.

Methods

We conducted a population-based study of adult patients with IPF in Olmsted County, Minnesota, from 1997 to 2005. Two methods were used to identify IPF cases, as defined by the 2002 American Thoracic Society/European Respiratory Society consensus statement: (1) usual interstitial pneumonia (UIP) on a surgical lung biopsy specimen or a definite UIP pattern on a high-resolution CT image (narrow criteria) and (2) UIP on a surgical lung biopsy specimen or a definite or possible UIP pattern on CT image (broad criteria).

Results

Of 596 patients screened for the possibility of pulmonary disease or pulmonary fibrosis over 9 years of follow-up, 47 cases had IPF. Of these, 24 met the narrow criteria. The age- and sex-adjusted incidence was 8.8/100,000 and 17.4/100,000 person-years, for narrow and broad criteria, respectively. The age-adjusted incidence was higher in men than in women, and among patients aged 70–79 years. During the study period, the incidence of IPF decreased (P < .001). On December 31, 2005, the age- and sex-adjusted prevalence was 27.9/100,000 and 63/100,000 persons by narrow and broad criteria, respectively. Thirty-seven patients experienced a total of 53 respiratory exacerbations (26 IPF related, 27 non-IPF related), and 34 (72%) patients died. The primary cause of death was IPF related in 16 (47%) patients. Median survival for narrow-criteria and broad-criteria incidence cases was 3.5 and 4.4 years, respectively.

Conclusions

The incidence of IPF in Olmsted County decreased over the study period. Nonprimary IPF respiratory exacerbations are as frequent as primary IPF respiratory exacerbations and an important cause of death.

Section snippets

Study Design and Settings

Following approval from the Mayo Foundation and Olmsted Medical Center Institutional Review Board, we conducted a community-based historical cohort study of IPF in Olmsted County (Fig 1). Population-based research is feasible in Olmsted County through the use of the unique resources of the Rochester Epidemiology Project (REP), a medical record linkage system for health-care providers to residents of Olmsted County.13, 14 Medical care is essentially self-contained within this community of

Results

During the 9-year study period, 596 Olmsted County residents aged 18 years or older were initially screened and identified to have possible pulmonary fibrosis (89% > 50 years old). After review of the medical records, 499 patients were excluded because they did not have idiopathic interstitial pneumonia (eg, chronic pulmonary infections), 42 had a known cause for pulmonary fibrosis (eg, connective tissue disease), three had an unlikely UIP pattern on CT image (with no lung biopsy), and five had

Discussion

To our knowledge, this is the first population-based study that provides an epidemiologic update of trends from the recent years in a general population of patients with IPF using ATS/ERS diagnostic criteria. We found that the adjusted incidence rate of IPF decreased during the 9-year study period, with peaks in 1998 and 2001.

The cause of the two distinct peaks observed in IPF incidence rate (1998 and 2001) is uncertain. Several explanations exist and include a reduction in disease latency

Acknowledgments

Author contributions: Dr Fernández Pérez: performed the study conceptualization and design; assisted in data collection; worked on clinical, radiologic, and pathologic case characterization; performed statistical analyses; and assisted in manuscript preparation, revision, and final approval.

Dr. Daniels: worked on clinical, radiologic, and pathologic case characterization and assisted in manuscript preparation, revision, and final approval.

Mr Schroeder: assisted in data collection; performed

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An abstract of this study was presented at the American College of Chest Physicians 74th Congress, October 25–30, 2008, Philadelphia, Pennsylvania.

Funding/support: This study was made possible by the Rochester Epidemiology Project (Grant R01-AR30582 from the National Institute of Arthritis and Musculoskeletal and Skin Diseases).

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/site/misc/reprints.xhtml).

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