Respiratory symptoms and lung function in patients treated for pulmonary tuberculosis in Malawi: a prospective cohort study

Abstract

Rationale: Pulmonary tuberculosis (PTB) can cause post-TB lung disease (PTLD) associated with respiratory symptoms, spirometric and radiological abnormalities. Understanding of the predictors and natural history of PTLD is limited.

Objectives: To describe the symptoms and lung function of Malawian adults up to 3 years following PTB-treatment completion, and to determine the evolution of PTLD over this period.

Methods: Adults successfully completing PTB treatment in Blantyre, Malawi were followed up for 3 years and assessed using questionnaires, post-bronchodilator spirometry, 6 min walk tests, chest X-ray and high-resolution CT. Predictors of lung function at 3 years were identified by mixed effects regression modelling.

Measurement and main results: We recruited 405 participants of whom 301 completed 3 years follow-up (mean (SD) age 35 years (10.2); 66.6% males; 60.4% HIV-positive). At 3 years, 59/301 (19.6%) reported respiratory symptoms and 76/272 (27.9%) had abnormal spirometry. The proportions with low FVC fell from 57/285 (20.0%) at TB treatment completion to 33/272 (12.1%), while obstruction increased from and 41/285 (14.4%) to 43/272 (15.8%) at 3 years. Absolute FEV₁ and FVC increased by mean 0.03 L and 0.1 L over this period, but FEV₁ decline of more than 0.1 L was seen in 73/246 (29.7%). Higher spirometry values at 3 years were associated with higher body mass index and HIV coinfection at TB-treatment completion.

Conclusion: Spirometric measures improved over the 3 years following treatment, mostly in the first year. However, a third of PTB survivors experienced ongoing respiratory symptoms and abnormal spirometry (with accelerated FEV₁ decline). Effective interventions are needed to improve the care of this group of patients.

Keywords: tuberculosis.

Figure 1

Participant flow diagram.

Figure 2

(A) FEV1 z-score change (non-normalised individual intervals). (B) FVC z-score change (non-normalised individual intervals). (C) Sankey plot showing change of spirometry pattern (using GLI and LLN in those who completed ATS standard spirometry) between each visit from TB treatment completion to the final 3-year visit. FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity.

Figure 3

Coefficient estimates (95% CI) for multivariable regression models with Z-score change in spirometry values in the 3-year follow-up period after TB treatment completion as the outcome and different covariate sets. FEV, forced expiratory volume; FVC, forced vital capacity; SES, socioeconomic status.