Background Evidence suggests an association between HIV infection and the presence of obstructive lung disease (OLD). However, the associations between specific markers of HIV infection and OLD remain unclear. A study was undertaken to determine the independent associations of HIV infection, CD4 cell count and plasma HIV viral load with the presence of OLD in an urban cohort.

Methods Clinical, laboratory and spirometric data from the AIDS Linked to the Intravenous Experience (ALIVE) study, an observational study of current and former injection drug users in Baltimore, Maryland, were analysed. Multivariable logistic regression models were generated to identify HIV infection indices independently associated with OLD.

Results Of 1077 participants (mean±SD age 48±8 years), 89% were African-American, 65% were men and 86% were current smokers. A total of 303 (28%) were HIV infected and 176 (16%) had spirometry-defined OLD. Higher viral load was independently associated with OLD. HIV-infected individuals with viral load >200 000 copies/ml had a 3.4-fold increase in the odds of OLD compared with HIV-negative participants (95% CI 1.24 to 9.39; p=0.02). The association between higher HIV viral load and OLD persisted after accounting for antiretroviral therapy use (OR 4.06, 95% CI 1.41 to 11.7; p=0.01). No association was observed between HIV serostatus or CD4 cell count and the presence of OLD.

Conclusion In a cohort at risk for OLD and HIV infection, high viral load but not CD4 cell count was associated with an increased prevalence of spirometry-defined OLD. These findings suggest that higher viral load may contribute mechanistically to the increased risk of OLD in patients with HIV infection.