Risk factors for pulmonary mycobacterial disease in South African gold miners - A case-control study

Pulmonary mycobacterial disease is common in miners. Risk factors for nontu berculous pulmonary mycobacterial (NTM) disease and tuberculosis (TB) in go ld miners were identified in a retrospective case-control study that includ ed 206 NTM patients and 381 TB patients of known human immunodeficiency vir us (HIV) status diagnosed between 1993 and 1996. A total of 180 HIV-tested trauma/surgical inpatients were selected as control patients. Both HIV infe ction (odds ratio [OR] 3.6 for NTM and 4.5 for TB patients) and higher grad es of silicosis (OR 5.0 for NTM and 4.9 for TB patients) were significantly more common in NTM and TB patients than in control patients. HIV prevalenc e rose in the control and both case groups during the study period. The ove rall HIV prevalence was 13.1% in NTM patients, 14.2% in TB patients, and 5. 6% in control patients. Previous TB (OR 9.6), premorbid focal radiological scarring (OR 7.4) and a dusty job at diagnosis (OR 2.4) were additional sig nificant risk factors for NTM disease. These findings suggest that the hist orically high incidence of NTM disease in miners is largely attributable to chronic chest disease from silica dust inhalation and prior TB. HIV infect ion has recently become an additional risk factor for mycobacterial disease in miners and is likely to become increasingly important as the HIV epidem ic progresses.