Twelve months fixed duration WHO multidrug therapy for multibacillary leprosy: incidence of relapses in Agra field based cohort study

BACKGROUND & OBJECTIVES: The reported low relapse rates after 24 months multidrug therapy (MDT) for multibacillary leprosy (MB) led to the recommendation of reducing duration of therapy to 12 months. However, only a few reports exist on long term follow up data after 12 months fixed duration therapy (FDT). The present study was done to assess the incidence of relapse in MB leprosy patients after 12 months treatment. METHODS: The leprosy patients detected in field surveys during 2001-2006 in Agra district, Uttar Pradesh, India, were put on WHO-MDT and followed up for treatment completion, relapse, reactions and development of disability. The assessment was done clinically by following up the patients until January 2011. Data collected were analyzed for risk and survival analysis. RESULTS: The incidence of relapse was found to be 1.97/100 person years of follow up. The incidence of relapse by age (34 yr vs >34 yr), sex (male vs female), delay in detection (<36 months vs >36 months) and smear status (smear +ve vs -ve) was not found to be significantly different but patients with no nerve involvement were observed to have significantly higher relapses than those with three or more nerve involvement (P<0.05). Similarly, borderline-borderline and BB with reaction (BB/BBR) patients were observed to have significantly high relapses than among those with borderline tuberculoid or BT with reaction (BT/BTR) or borderline lipromatous/lepromatous/neuritic (BL/LL/N) type of leprosy (P<0.01). INTERPRETATION & CONCLUSION: From the observations in the study, it can be suggested that relapses occur in 12 months FDT and almost as much as reported in 24 months FDT for MB leprosy. Although, early relapses may be due to insufficient treatment, late relapses may be due to persistent dormant mycobacteria. However, a study relating to immunological response of treatment and change in immunological profile relating to the occurrence of relapses and its clinical correlates may suggest better information on causes of relapses.