Excess lung function decline in gold miners following pulmonary tuberculosis
- 1Mailman School of Public Health, Columbia University, New York, USA
- 2School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa
- 3National Institute for Occupational Safety and Health, West Virginia, USA
- 4Department of Medicine, University of Cape Town, Cape Town, South Africa
- 5Aurum Institute for Health Research, Johannesburg, South Africa
- Correspondence to Rodney Ehrlich, School of Public Health and Family Medicine, University of Cape Town, Observatory 7925, South Africa;
- Received 4 November 2009
- Accepted 5 August 2010
- Published Online First 25 September 2010
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 (FEV1).
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 FEV1 (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.
N White died on 6 November, 2004.
Funding Mine Health and Safety Council, South Africa.
Competing interests RIE has written expert reports for use in silicosis litigation. GJC was employed by the AngloGold Ashanti gold mining company at the time of the study. The remaining authors have no competing interests.
Ethics approval This study was conducted with the approval of the AngloGold Health Services Medical Research Ethics Committee and the University of the Witwatersrand Committee for Research on Human Subjects and all participants gave written informed consent.
Provenance and peer review Not commissioned; externally peer reviewed.