High-attenuation areas on chest computed tomography and clinical respiratory outcomes in community-dwelling adults

Rationale: Areas of increased lung attenuation visualized by computed tomography are associated with all-cause mortality in the general population. It is uncertain whether this association is attributable to interstitial lung disease (ILD). Objectives: To determine whether high-attenuation areas are associated with the risk of ILD hospitalization and mortality in the general population. Methods: We performed a cohort study of 6,808 adults aged 45–84 years sampled from six communities in the United States. High-attenuation areas were defined as the percentage of imaged lung volume with attenuation values between 2600 and 2250 Hounsfield units. An adjudication panel determined ILD hospitalization and death. Measurements and Main Results: After adjudication, 52 participants had a diagnosis of ILD during 75,232 person-years (median, 12.2 yr) of follow-up. There were 48 hospitalizations attributable to ILD (crude rate, 6.4 per 10,000 person-years). Twenty participants died as a result of ILD (crude rate, 2.7 per 10,000 person-years). High-attenuation areas were associated with an increased rate of ILD hospitalization (adjusted hazard ratio, 2.6 per 1-SD increment in high-attenuation areas; 95% confidence interval, 1.9–3.5; P, 0.001), a finding that was stronger among men, African Americans, and Hispanics. High-attenuation areas were also associated with an increased rate of ILD-specific death (adjusted hazard ratio, 2.3; 95% confidence interval, 1.7–3.0; P, 0.001). Our findings were consistent among both smokers and nonsmokers. Conclusions: Areas of increased lung attenuation are a novel risk factor for ILD hospitalization and mortality. Measurement of high-attenuation areas by screening and diagnostic computed tomography may be warranted in at-risk adults.