Evaluating the effectiveness of a conditional food voucher programme on antiretroviral therapy adherence among food-insecure people living with HIV in the Lesotho highlands: a methodological framework

Food insecurity is a significant barrier to antiretroviral therapy (ART) adherence among people living with HIV (PLHIV) in sub-Saharan Africa. While conditional food voucher programmes integrated with HIV care are being implemented, rigorous methodological frameworks for evaluating them in remote, highland settings such as Lesotho remain scarce. This methodology article presents a framework for evaluating the effectiveness of a conditional food voucher programme on ART adherence among food-insecure PLHIV in the Lesotho highlands. Its primary objective is to detail the design of a mixed-methods, quasi-experimental study for assessing the programme’s impact. The framework employs a quasi-experimental, longitudinal design with intervention and comparison groups. It integrates quantitative measures, including pharmacy refill data for adherence and the household food insecurity access scale, with qualitative components comprising in-depth interviews and focus group discussions. The design specifies sampling, data collection tools, and procedures tailored to the highland context. The analysis plan incorporates propensity score matching and thematic analysis. As a methodology article, it presents no empirical results. However, the proposed framework is designed to detect a hypothesised minimum 15-percentage-point improvement in optimal ART adherence (≥95% of doses) within the intervention group relative to the comparison group. This methodological framework offers a rigorous and contextually adapted blueprint for assessing the impact of a conditional food voucher programme on ART adherence. It addresses key challenges in evaluating complex public health interventions within resource-limited, remote settings. Researchers and programme implementers should consider this framework when designing evaluations of integrated nutrition-HIV interventions in similar contexts. Emphasis is placed on the need for robust comparison groups, mixed methods, and context-specific adherence measures. HIV, antiretroviral therapy adherence, food insecurity, conditional vouchers, Lesotho, methodology This article contributes a detailed methodological framework for evaluating food voucher programmes in remote, highland settings, aiming to strengthen the evidence base for integrated nutrition and HIV care interventions.