Geographic and socioeconomic factors associated with leprosy treatment default: An analysis from the 100 Million Brazilian Cohort

Background: Although leprosy is largely curable with multidrug therapy, incomplete treatment limits therapeutic effectiveness and is an important obstacle to disease control. To inform efforts to improve treatment completion rates, we aimed to identify the geographic and socioeconomic factors associated with leprosy treatment default in Brazil. Methodology/Principal findings: Using individual participant data collected in the Brazilian national registries for social programs and notifiable diseases and linked as part of the 100 Million Brazilian Cohort, we evaluated the odds of treatment default among 20,063 leprosy cases diagnosed and followed up between 2007 and 2014. We investigated geographic and socioeconomic risk factors using a multivariate hierarchical analysis and carried out additional stratified analyses by leprosy subtype and geographic region. Over the duration of follow-up, 1,011 (5.0%) leprosy cases were observed to default from treatment. Treatment default was markedly increased among leprosy cases residing in the North (OR = 1.57; 95%CI 1.25–1.97) and Northeast (OR = 1.44; 95%CI 1.17–1.78) regions of Brazil. The odds of default were also higher among cases with black ethnicity (OR = 1.29; 95%CI 1.01–1.69), no income (OR = 1.41; 95%CI 1.07–1.86), familial income ≤ 0.25 times Brazilian minimum wage (OR = 1.42; 95%CI 1.13–1.77), informal home lighting/no electricity supply (OR = 1.53; 95%CI 1.28–1.82), and household density of > 1 individual per room (OR = 1.35; 95%CI 1.10–1.66). Conclusions: The findings of the study indicate that the frequency of leprosy treatment default varies regionally in Brazil and provide new evidence that adverse socioeconomic conditions may represent important barriers to leprosy treatment completion. These findings suggest that interventions to address socioeconomic deprivation, along with continued efforts to improve access to care, have the potential to improve leprosy treatment outcomes and disease control. Author summary: While the leprosy new case detection has been decreasing worldwide since the introduction of multidrug therapy (MDT) in the 1980s, treatment default remains an important risk factor for leprosy-associated disability and an obstacle to disease control and elimination. Treatment default occurs when an individual with leprosy does not take the prescribed number of doses required for treatment with MDT. We hypothesized that the frequency of defaulting may be influenced by geographic factors, especially as related to access to care, and socioeconomic factors, such as income, education, and household living conditions. To test this hypothesis, we investigated geographic and socioeconomic factors associated with leprosy treatment default among 20,063 new leprosy cases followed as part of the 100 Million Brazilian Cohort between 2007 and 2014. In total, 5.0% of the leprosy patients defaulted from MDT. Among the associated factors, we found that having residency in the North and Northeast of Brazil, black ethnicity, low familial income, lack of formal electricity, and a high household density were associated with higher odds of leprosy treatment default. Overall, these findings highlight the need for tailoring MDT strategies for vulnerable populations in high-burden communities and suggest that social policies aiming to alleviate poverty should be investigated as potential tools for improving leprosy treatment completion.