Abstract
Residual pulmonary impairment is common after treatment for tuberculosis (TB). Lung function data in patients with HIV-associated TB are scarce, especially in the context of paradoxical TB-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 TB and CD4 counts ≤100 cells·μL−1 and assess the effect of prophylactic prednisone and the development of paradoxical TB-IRIS on pulmonary impairment.We performed spirometry, 6-min walk test (6MWT) and chest radiography at baseline (week 0) and at weeks 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 TB commencing antiretroviral therapy.153 participants underwent spirometry and/or 6MWT 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 m greater 6-min walk distance and a 4.9% higher percentage of predicted forced expiratory volume in 1 s 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 TB. 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.
Highlights
Tuberculosis (TB) is frequently complicated by lung function impairment
The effect of prophylactic prednisone on pulmonary function was tested using a test of the interaction of prednisone and visit number; participants receiving prednisone as treatment for TBassociated immune reconstitution inflammatory syndrome (TB-IRIS) were analysed in their intention-to-treat arm
The flow of participants is described in figure 1; baseline characteristics are summarised in table 1. 71 (46%) participants developed TB-IRIS: 30 in the prednisone and 41 in the placebo arm; 46 (30%) participants received open-label prednisone as treatment for TB-IRIS: 16 in the prednisone and 30 in the placebo arm
Summary
Tuberculosis (TB) is frequently complicated by lung function impairment. The odds of abnormal spirometric test results are two- to three-fold higher in patients with a history of TB compared to those without a history of TB, with both obstructive and/or restrictive impairments occuring [1, 2]. Two recent studies suggested that TB-IRIS may cause lung function impairment [18, 19]; one showing increased inflammation, as assessed by positron emission tomography (PET)-computed tomography (CT) scan, was associated with worse lung function outcomes [18]. In these cohorts only small numbers of patients developed predefined TB-IRIS, yet the authors hypothesise that increases in pulmonary inflammation can occur as part of not clinically recognised TB-IRIS. The only other study exploring the relationship between TB-IRIS and lung function found worse spirometric outcomes in the three patients who developed TB-IRIS compared to 11 controls [15]
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