Development and Progression of Radiologic Abnormalities in Individuals at Risk for Familial Interstitial Lung Disease
Margaret L. Salisbury, J.C. Hewlett, Guixiao Ding, Cheryl Markin, Katrina Douglas, Wendi R. Mason, Adam Guttentag, John A. Phillips, Joy D. Cogan, Sara Reiss, Daphne B. Mitchell, Pingsheng Wu, Lisa R. Young, Lisa Lancaster, James E. Loyd, Stephen M. Humphries, David A. Lynch, Jonathan A. Kropski, Timothy S. Blackwell
Abstract
Abstract Rationale The preclinical natural history of progressive lung fibrosis is poorly understood. Objectives Our goals were to identify risk factors for interstitial lung abnormalities (ILA) on high-resolution computed tomography (HRCT) scans and to determine progression toward clinical interstitial lung disease (ILD) among subjects in a longitudinal cohort of self-reported unaffected first-degree relatives of patients with familial interstitial pneumonia. Methods Enrollment evaluation included a health history and exposure questionnaire and HRCT scans, which were categorized by visual assessment as no ILA, early/mild ILA, or extensive ILA. The study endpoint was met when ILA were extensive or when ILD was diagnosed clinically. Among subjects with adequate study time to complete 5-year follow-up HRCT, the proportion with ILD events (endpoint met or radiographic ILA progression) was calculated. Measurements and Main Results Among 336 subjects, the mean age was 53.1 (SD, 9.9) years. Those with ILA (early/mild [n = 74] or extensive [n = 3]) were older, were more likely to be ever smokers, had shorter peripheral blood mononuclear cell telomeres, and were more likely to carry the MUC5B risk allele. Self-reported occupational or environmental exposures, including aluminum smelting, lead, birds, and mold, were independently associated with ILA. Among 129 subjects with sufficient study time, 25 (19.4%) had an ILD event by 5 years after enrollment; of these, 12 met the study endpoint and another 13 had radiologic progression of ILA. ILD events were more common among those with early/mild ILA at enrollment (63.3% vs. 6.1%; P < 0.0001). Conclusions Rare and common environmental exposures are independent risk factors for radiologic abnormalities. In 5 years, progression of ILA occurred in most individuals with early ILA detected at enrollment.