Cigarette smoking: a risk factor for idiopathic pulmonary fibrosis.

TLDR

The study aimed to evaluate whether cigarette smoking is associated with idiopathic pulmonary fibrosis through a multicenter case‑control design. Researchers recruited 248 IPF cases and 491 matched controls, collected exposure histories via telephone interviews and clinical data, and used conditional logistic regression to assess smoking risk. Smoking history increased IPF risk (OR 1.6 overall; OR 1.9 for former smokers; OR 2.3 for 21–40 pack‑years), with the highest risk among recent quitters.

Abstract

We conducted a multicenter case-control study of clinically and histologically diagnosed idiopathic pulmonary fibrosis (IPF), a chronic diffuse interstitial lung disease of unknown cause. The study included 248 cases, and 491 control subjects identified through random-digit dialing, matched to cases in sex, age, and geographic region. Telephone interviews were conducted with both cases and controls to collect information on potential risk factors for IPF, including smoking and household, occupational, and environmental exposures. Pulmonary function tests, X-rays, computed tomographic (CT) scans of the chest, and lung biopsy reports were submitted by referring centers to support the diagnoses. An a priori hypothesis that smoking is associated with IPF was examined with conditional logistic regression analyses. More cases (72%) than control subjects (63%) had a history of ever smoking. The odds ratio (OR) for ever smoking was 1.6 (95% CI: 1.1 to 2.4). Risk was significantly elevated for former smokers (OR = 1.9; 95% CI: 1.3 to 2.9) and for smokers with 21 to 40 pack-yr (OR = 2.3; 95% CI: 1.3 to 3.8). A history of smoking is associated with an increased risk for the development of IPF. Although there was no clear exposure-response pattern with cumulative consumption of cigarettes, there was a trend for time since cessation of smoking, with the highest risk for those who had most recently quit.