HIV Infection Is Independently Associated with Increased CT Scan Lung Density.

RATIONALE AND OBJECTIVES: Noninfectious pulmonary complications are common among HIV-infected individuals and may be detected early by quantitative computed tomography (CT) scanning. The association of HIV disease markers with CT lung density measurement remains poorly understood.

MATERIALS AND METHODS: One hundred twenty-five participants free of spirometry-defined lung disease were recruited from a longitudinal cohort study of HIV-infected and HIV-uninfected individuals to undergo standardized CT scan of the chest. Parenchymal density for the entire lung volume was calculated using computerized software. Qualitative assessment of CT scans was conducted by two radiologists masked to HIV status. Linear regression models were developed to determine the independent association of markers of HIV infection on inspiratory scan mean lung density (MLD).

RESULTS: HIV-infected participants had a significantly higher MLD (denser lung) compared to HIV-uninfected participants (-815 Hounsfield unit [HU] vs -837 HU; P = 0.002). After adjusting for relevant covariates, HIV infection was independently associated with 19.9 HU higher MLD (95% CI 6.04 to 33.7 HU; P = 0.005). In qualitative assessment, only ground glass attenuation and cysts were noted more commonly among HIV-infected individuals compared to HIV-uninfected individuals (34% vs 17% [P = 0.045] and 27% vs 10% [P = 0.03], respectively). No qualitative radiographic abnormalities attenuated the association between HIV infection and increased MLD.

CONCLUSIONS: HIV infection is independently associated with increased lung density. Although qualitative CT abnormalities were common in this cohort, only ground glass attenuation and cysts were noted more frequently in HIV-infected participants, suggesting that the increased lung density observed among HIV-infected individuals may be associated with subclinical inflammatory lung changes.