Relapses in multibacillary leprosy patients: effect of length of therapy.

Two groups of MB leprosy patients, one treated to the point of smear negativity (TSN) and the other given therapy for fixed duration (24 doses of WHO MB regimen) (FDT), were compared for relapse rates during treatment and in the post-treatment period. During the follow-up of 980.2 person years in 260 patients treated with FDT, 20 relapses (2.04/100 patient years) were observed. In the other group of 301 patients, who received therapy till smear negativity, 12 relapses in 1085.46 person years (1.10/100 patient years) occurred. Comparison of survival rates (without relapse) has shown that although there is no difference up to 4 years, the risk of relapse was significantly higher on longer follow-up in the FDT group. In addition, when patients were compared on the basis of initial bacterial load, it was found that the relapse rates in patients with BI > or = 4 was significantly higher (P < 0.01) in the FDT group as compared to those receiving treatment till the point of smear negativity (4.29 versus 1.27/100 patient years). All the relapsed patients responded to retreatment with the same drug combination, indicating that the exacerbation in their condition was because of insufficient treatment. It is suggested that to prevent or reduce relapses, treatment where feasible would be continued till smear negativity, at least in patients with high BI.