Effectiveness of single dose rifampicin in preventing leprosy in close contacts of patients with newly diagnosed leprosy: cluster randomised controlled trial

Objective To determine the effectiveness of chemoprophylaxis using a single dose of rifampicin to prevent leprosy in close contacts. Design Single centre, double blind, cluster randomised, placebo controlled trial. Setting Leprosy control programme in two districts of northwest Bangladesh with a population of more than four million. Participants 28 092 close contacts of 1037 patients with newly diagnosed leprosy. 21711 contacts fulfilled the study requirements. Interventions A single dose of rifampicin or placebo given to close contacts in the second month of starting the index patient's treatment, with follow-up for four years. Main outcome measure Development of clinical leprosy. Results 18 869 of the 21711 contacts (86.9%) were followed-up at four years. Ninety one of 9452 contacts in the placebo group and 59 of 9417 in the rifampicin group had developed leprosy. The overall reduction in incidence of leprosy using a single dose of rifampicin in the first two years was 57% (95% confidence interval 33% to 72%). The groups did not differ between two and four years. The overall number needed to treat (NNT) to prevent a single case of leprosy among contacts was 297 (95% confidence interval 176 to 537). Differences were found between subgroups at two years, both in reduction of incidence and in NNT. Conclusion A single dose of rifampicin given to contacts of patients with newly diagnosed leprosy is effective at preventing the development of clinical leprosy at two years. The effect was maintained, but no difference was seen between the placebo and rifampicin groups beyond two years. Trial registration Current Controlled Trials ISRCTN61223447.