Factors associated with pulmonary impairment in HIV-infected South African adults

BACKGROUND: HIV-infected individuals have increased risk of developing obstructive lung disease (OLD). Studies from developed countries report high viral load, low CD4 counts, and anti-retroviral therapy (ART) to be associated with OLD; but these findings may not be generalizable to populations in resource-limited settings. METHODS: We conducted a prospective cohort study of lung function in 730 HIV-infected black South African adults. Pre-bronchodilator spirometry was performed at enrollment and repeated annually for three years. Logistic regression models were used to identify factors associated with OLD, defined as FEV1/FVC<0.70, at enrollment. Excess annual declines in FEV1 and FVC were modelled as the product-term of follow-up time and exposures using random effects regression. RESULTS: Median (IQR) age at enrollment was 36 (32–41) years, 85% were female and 30% ever-smoked with a median (IQR) exposure of 3 (1–6) pack-years. Median (IQR) CD4 count and viral load at enrollment were 372 (261–518) cells/mm(3) and 2655 (91–13,548) copies/mL respectively. Overall, 25% were receiving ART at enrollment, 16% of whom reported at least 6 months of ART receipt. OLD was found in 35 (5%) at enrollment. Increasing age (aOR = 2.08 per 10-years [95%CI 1.22–3.57], p = 0.007), current smoking (aOR = 3.55 [95%CI 1.20–10.53], p = 0.02), and CRP (aOR = 1.01 per unit-increase [95%CI 1.00–1.03], p = 0.04) were significantly associated with OLD at enrollment; while increasing CD4 count (aOR = 1.02 per-100 cells/mm(3) [95%CI 0.85–1.22], p = 0.82), viral load (aOR = 0.67 per log-increase [95%CI 0.43–1.10], p = 0.12) and receipt of ART (aOR = 0.57 [95%CI 0.18–1.75], p = 0.32) were not. The median (IQR) follow-up time was 18 (12–24) months. Participants with a history of tuberculosis (TB) had a 35 mL (95%CI 2–68, p = 0.03) and 57 mL (95%CI 19–96, p = 0.003) per year excess loss of FEV1 and FVC respectively. CONCLUSION: Prevalent OLD was associated with older age, current smoking and higher CRP levels, but not CD4 counts and ART, in HIV-infected South African adults. Better understanding of the long-term effects of TB, smoking and inflammation on lung function in HIV-infected populations is urgently needed.