Relapses in multibacillary leprosy patients: a retrospective cohort of 11 years in Colombia.

OBJECTIVES To determine the frequency and factors associated with relapse in multibacillary leprosy. DESIGN We performed a retrospective cohort study on multibacillary leprosy patients treated at Centro Dermatologico Federico Lleras Acosta between January 1994 and December 2004. By survival analysis we studied the incidence density for recurrence and bacillary index conversion. The assessment of risk factors associated with the occurrence of relapse was constructed using a Cox regression model. RESULTS We included 299 cases of which 243 received WHO-MB MDT on a regular basis, and followed them up to assess the frequency of relapses. We obtained 490 person-years of follow-up and an incidence density of 6.70 relapses/100 patient-years that was higher than most of the data reported in the literature. The relapse rate was 9.80 per 100 person-years when the initial bacillary index was > or = 2.0 and 5.60 relapses/100 patient-years when it was < 2 (P = 0.03). The relapse rate increased to 7.70/100 patient-years among those treated with WHO-MB 24 month fixed-dose, and it reduced to 5.70/100 patient-years when treated until smear negative. The variables that showed association with relapse were: initial bacillary index > or = 2.0, antireactional treatment and clinical classification of lepromatous leprosy. For each variable, the risk was four to five times more likely to present relapse. We also found that 21 patients' BI became negative per 100 treated for 1 year with WHO-MB MDT. CONCLUSIONS We found a high relapse rate associated with initial high bacillary index in the Colombian population. Among the patients who received MDT on a regular basis 33 out of 165 (20%) relapsed.