Variation in attrition at subnational level: review of the Botswana National HIV/AIDS Treatment (Masa) programme data (2002–2013)

OBJECTIVE: To evaluate the variation in all-cause attrition [mortality and loss to follow-up (LTFU)] among HIV-infected individuals in Botswana by health district during the rapid and massive scale-up of the National Treatment Program. METHODS: Analysis of routinely collected longitudinal data from 226 030 patients who received ART through the Botswana National HIV/AIDS Treatment Program across all 24 health districts from 2002 to 2013. A time-to-event analysis was used to measure crude mortality and loss to follow-up rates (LTFU). A marginal structural model was used to evaluate mortality and LTFU rates by district over time, adjusted for individual-level risk factors (e.g. age, gender, baseline CD4, year of treatment initiation and antiretroviral regimen). RESULTS: Mortality rates in the districts ranged from the lowest 1.0 (95% CI 0.9-1.1) in Selibe-Phikwe, to the highest 5.0 (95% CI 4.0-6.1), in Mabutsane. There was a wide range of overall LTFU across districts, including rates as low as 4.6 (95% CI 4.4-4.9) losses per 100 person-years in Ngamiland, and 5.9 (95% CI 5.6-6.2) losses per 100 person-years in South East district, to rates as high as 25.4 (95% CI 23.08-27.89) losses per 100 person-years in Mabutsane and 46.3 (95% CI 43.48-49.23) losses per 100 person-years in Okavango. Even when known risk factors for mortality and LTFU were adjusted for, district was a significant predictor of both mortality and LTFU rates. CONCLUSION: We found statistically significant variation in attrition (mortality and LTFU) and data quality among districts. These findings suggest that district-level contextual factors affect retention in treatment. Further research needs to investigate factors that can potentially cause this variation.