The study was large, involving 23,874 miners from four mines, and retrospective in design, drawing its results from the medical records available for each miner. All subjects were black men between 18 and 65 years of age. They were divided into three groups: those who were HIV-negative throughout the study, those who were HIV-positive on study entry, and those whose infection status changed from negative to positive during the study. Miners were followed until they developed pulmonary tuberculosis, left the mines, or died. Tuberculosis incidence not only doubled within the first year of HIV infection but also increased four-fold after two years, with a further slight increase in those infected for longer periods of up to seven years.
Sonnenberg and colleagues explained that several characteristics of the gold mines greatly facilitated their research: a very high incidence of tuberculosis among the miners, due to crowded conditions and other work-related factors; the fact that the miners lived on-site at the mines, making their external environments relatively uniform; and the mines' provision of free, high-quality health care to the miners, including a voluntary HIV testing program and tuberculosis screening and treatment programs. The unique setting of the gold mines also provides a caveat: because the study population was not diverse and was characterized by unusually high rates of tuberculosis, the results may not be appl
Contact: Diana Olson
Infectious Diseases Society of America