Patient outcomes associated with post-tuberculosis lung damage in Malawi: a prospective cohort study

Abstract

Background: Post-tuberculosis lung damage (PTLD) is a recognised consequence of pulmonary TB (pTB). However, little is known about its prevalence, patterns and associated outcomes, especially in sub-Saharan Africa and HIV-positive adults.

Methods: Adult (≥15 years) survivors of a first episode of pTB in Blantyre, Malawi, completed the St George's Respiratory Questionnaire, 6-minute walk test, spirometry and high-resolution CT (HRCT) chest imaging at TB treatment completion. Symptom, spirometry, health seeking, TB-retreatment and mortality data were collected prospectively to 1 year. Risk factors for persistent symptoms, pulmonary function decline and respiratory-related health-seeking were identified through multivariable regression modelling.

Results: Between February 2016 and April 2017, 405 participants were recruited. Median age was 35 years (IQR: 28 to 41), 77.3% (313/405) had had microbiologically proven pTB, and 60.3% (244/403) were HIV-positive. At pTB treatment completion, 60.7% (246/405) reported respiratory symptoms, 34.2% (125/365) had abnormal spirometry, 44.2% (170/385) had bronchiectasis ≥1 lobe and 9.4% (36/385) had ≥1 destroyed lobe on HRCT imaging. At 1 year, 30.7% (113/368) reported respiratory symptoms, 19.3% (59/305) and 14.1% (43/305) of patients had experienced declines in FEV₁ or FVC of ≥100 mL, 16.3% (62/380) had reported ≥1 acute respiratory event and 12.2% (45/368) had symptoms affecting their ability to work.

Conclusions: PTLD is a common and under-recognised consequence of pTB that is disabling for patients and associated with adverse outcomes beyond pTB treatment completion. Increased efforts to prevent PTLD and guidelines for management of established disease are urgently needed. Low-cost clinical interventions to improve patient outcomes must be evaluated.

Keywords: bronchiectasis; clinical epidemiology; respiratory infection; tuberculosis.

Figure 1

Participant flow diagram.

Figure 2

High resolution CT (HRCT) and chest x-ray imaging from participants with severe bronchiectasis (panel 1) or destroyed lung (panels 2 and 3, paired imaging from the same individuals), captured at TB-treatment completion. Bronchiectasis: Airway lumen diameter greater than accompanying pulmonary artery outer diameter, or airways visible <1 cm of lung periphery, or lack of normal airway tapering. Destroyed lung: ≥1 lung lobe in which ≥90% of parenchyma occupied by atelectasis or parenchymal banding, or destroyed by cavities/cystic airspaces.

Figure 3

The extent of parenchymal and airway pathology seen on high-resolution CT imaging at TB treatment completion, stratified by HIV status (n=385). HRCT data missing for n=25: pregnancy (n=3), unable to travel to CT-scanner (n=6), missed appointments (n=8) and machine errors (n=3). ˆ Bronchial wall thickening: Not reported for those with lobar destruction preventing evaluation of bronchial wall thickness in ≥1 lung lobe (n=58). *p<0.05, **p<0.01, ***p<0.001.