(HealthDay News) — Community-wide isoniazid preventive therapy does not improve tuberculosis (TB) control in miners, according to a study published in the Jan. 23 issue of the New England Journal of Medicine.

Gavin J. Churchyard, M.B., B.Ch., Ph.D., from University of the Witwatersrand in Johannesburg, and colleagues randomized 15 clusters of miners to either an intervention (40,981 miners; eight clusters) or control (37,763 miners; seven clusters). The intervention involved offering all miners TB screening and referral for treatment if diagnosed. For those in the intervention not diagnosed, isoniazid preventive therapy was offered.

The researchers found that 66.2% of the miners in the intervention cluster underwent screening, 87.2% of whom (23,659 miners) initiated isoniazid. The incidence of TB was not reduced with the intervention (TB rates: 3.02 per 100 person-years with intervention and 2.95 per 100 person-years for controls; P = 0.98; adjusted rate ratio [aRR], 0.96; P = 0.71). The prevalence of tuberculosis was also similar between groups (2.35% versus 2.14%; adjusted prevalence ratio, 0.98; P = 0.90). In 10,909 miners assessed for the direct effect of isoniazid, there was a reduced incidence of TB during treatment (1.10 cases per 100 person-years versus 2.91 cases per 100 person-years among controls; aRR, 0.42; P = 0.03), but there was a subsequent rapid loss of protection.

“In conclusion, we found that a nine-month course of community-wide isoniazid preventive therapy did not improve tuberculosis control in South African gold mines,” Churchyard and colleagues write.

The isoniazid used in the study was donated by Sanofi-Aventis.

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