MedPage Today (01.22.2014)
Medpage Today reported that a clinical trial using preventive TB therapy with South African gold miners failed. The miners have a high TB risk as they live and work in close quarters and are exposed to silica dust. The researchers, including Gavin Churchyard, MBBCh, PhD, of Aurum Institute in Johannesburg, tested preventive treatment for a large group of miners in a cluster-randomized trial.
The researchers divided 40,981 miners into eight intervention clusters and 37,763 into seven control clusters. The intervention included TB screening and treatment referral if the participants had active disease. Researchers offered participants without active disease nine months of isoniazid preventive therapy. The study outcome was cluster-level TB incidence during the year and after the nine-month intervention; the secondary outcome was TB prevalence at the end of the study. In the intervention cluster, researchers screened 27,126 miners (66.2 percent) and put 23,659 on isoniazid. Also, 79 percent of miners received isoniazid for six months based on the cluster.
Results show that while miners were taking isoniazid, they were less likely to develop TB, but the preventive effect stopped after the study ended. The researchers discussed possible reasons for the results as well as the limits of the study.
The full report, “A Trial of Mass Isoniazid Preventive Therapy for Tuberculosis Control,” was published in the New England Journal of Medicine (2014; 370: 301–310).