The Differential Impact of Emphysema on Respiratory Symptoms and 6-Minute Walk Distance in HIV Infection

Background: Emphysema is more prevalent in HIV-infected (HIV+) patients independent of smoking behavior. Nonetheless, health effects of emphysema in this population are poorly understood. We determined whether emphysema is associated with a greater burden of pulmonary symptoms and a lower 6-minute walk distance (6MWD) in HIV+ compared with HIV-uninfected (HIV-) subjects. Methods: We performed a cross-sectional analysis of 170 HIV+ and 153 HIV- subjects in the Examinations of HIV-Associated Lung Emphysema (EXHALE) cohort study. Subjects completed a self-assessment of respiratory symptoms, pulmonary function testing, and 6MWD testing as well as a chest computed tomography to determine emphysema severity. We used regression models to determine the association of emphysema with respiratory symptoms and 6MWD in HIV+ subjects and compared this to HIV- subjects. Results: Models stratified by HIV status demonstrated an association between >10% radiographic emphysema and chronic cough and/or phlegm and 6MWD in HIV+ subjects. These associations persisted among the subset without airflow obstruction: those with emphysema had 4.2 (95% confidence interval: 1.3 to 14) times the odds of chronic cough and/or phlegm and walked 60 m (95% confidence interval: 26 to 93) less distance than those without emphysema. There was no association between >10% emphysema and symptoms or 6MWD in HIV- subjects. Conclusions: In our cohort, >10% radiographic emphysema was associated with chronic cough and/or phlegm and lower 6MWD in HIV+ but not HIV- subjects. These findings were robust even among HIV+ subjects with milder forms of emphysema and those without airflow obstruction, highlighting the clinical impact of emphysema in these patients.