The effect of HIV-associated tuberculosis, tuberculosis-IRIS, and prednisone on lung function

Abstract

Residual pulmonary impairment is common after treatment for tuberculosis. Lung function data in patients with HIV-associated tuberculosis are scarce, especially in the context of paradoxical tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) and prophylactic prednisone. We aimed to determine the prevalence of lung function abnormalities in patients with HIV-associated tuberculosis and CD4 counts ≤ 100 cells/μl and assess the effect of prophylactic prednisone and the development of paradoxical TB-IRIS on pulmonary impairment.We performed spirometry, six-minute walk test, and chest radiography at baseline (week 0), week 4, 12, and 28 in participants of the PredART trial, which evaluated a 28-day course of prednisone to prevent TB-IRIS in patients with HIV-associated tuberculosis commencing antiretroviral therapy. 153 participants underwent spirometry and/or six-minute walk test at one or more time points. Abnormal spirometry measurements were present in 66% of participants at week 0 and 50% at week 28; low forced vital capacity was the commonest abnormality. Chest radiographs showed little or no abnormalities in the majority of participants.Prednisone use resulted in a 42 meters greater six-minute walk distance and a 4.9 % higher percentage of predicted forced expiratory volume in 1 second at week 4; these differences were no longer significantly different from week 12 onwards. TB-IRIS did not significantly impair lung function outcome. Residual pulmonary impairment is common in HIV-associated tuberculosis. In patients with low CD4 counts, neither prophylactic prednisone as used in our study nor the development of TB-IRIS significantly affected week 28 pulmonary outcome.