Lung Volumes and Emphysema in Smokers with Interstitial Lung Abnormalities

BACKGROUND—Cigarette smoking is associated with emphysema and radiographic interstitial lung abnormalities. The degree to which interstitial lung abnormalities are associated with reduced total lung capacity and the extent of emphysema is not known. METHODS—We looked for interstitial lung abnormalities in 2416 (96%) of 2508 high-resolution computed tomographic (HRCT) scans of the lung obtained from a cohort of smokers. We used linear and logistic regression to evaluate the associations between interstitial lung abnormalities and HRCT measurements of total lung capacity and emphysema. RESULTS—Interstitial lung abnormalities were present in 194 (8%) of the 2416 HRCT scans evaluated. In statistical models adjusting for relevant covariates, interstitial lung abnormalities were associated with reduced total lung capacity (−0.444 liters; 95 % confidence interval [CI], −0.596 to −0.292; P<0.001) and a lower percentage of emphysema defined by lung-attenuation thresholds of −950 Hounsfield units (−3%; 95 % CI, −4 to −2; P<0.001) and −910 Hounsfiel