Excess lung function decline in gold miners following pulmonary tuberculosis

Abstract

Background: Few if any studies of the association between pulmonary tuberculosis (TB) and lung function loss have had access to premorbid lung function values.

Methods: Using a retrospective cohort design, the study recruited employed South African gold miners who had undergone a pulmonary function test (PFT) between January 1995 and August 1996. The 'exposed' group comprised 185 miners treated for pulmonary TB after the initial PFT and the 'unexposed' group comprised 185 age-matched miners without TB. All participants had a follow-up PFT between April and June 2000. The outcome of interest was decline in lung function during the follow-up period as measured by forced vital capacity (FVC) and forced expiratory volume in 1 s(FEV(1)).

Results: After controlling for age, height, baseline lung function, silicosis, years of employment, smoking and other respiratory diagnoses, pulmonary TB during the follow-up period was associated with a mean excess loss of 40.3 ml/year in FEV(1) (95% CI 25.4 to 55.1) and 42.7 ml/year in FVC (95% CI 27.0 to 58.5). Lung function loss was greater among those with more severe or later clinical presentation of TB. Breathlessness was twice as common among TB cases (OR 2.20, 95% CI 1.18 to 4.11).

Conclusion: There is a need for greater clinical recognition of the long-term respiratory consequences of treated pulmonary TB. Early detection of TB would help to reduce these sequelae and remains a priority, particularly in a workforce already subject to silica dust disease. However, strategies such as dust control, worker education about TB and dust and TB preventive therapy are also needed to avert the disease itself.