Protocol of a cost-effectiveness analysis of a combined intervention for depression and parenting compared with enhanced standard of care for perinatally depressed, HIV-positive women and their infants in rural South Africa.

INTRODUCTION: Poverty, HIV and perinatal depression represent a triple threat to public health in sub-Saharan Africa because of their combined negative effects on parenting and child development. In the resource-constrained context of low-income and middle-income countries, a lay-counsellor-delivered intervention that combines a psychological and parenting intervention could offer the potential to mitigate the consequences of perinatal depression while also optimising scarce resources for healthcare.Measuring the cost-effectiveness of such a novel intervention will help decision-makers to better understand the relative costs and effects associated with replicating the intervention, thereby supporting evidence-based decision-making. This protocol sets out the methodological framework for analysing the cost-effectiveness of a cluster randomised controlled trial (RCT) that compares a combined intervention to enhanced standard of care when treating depressed, HIV-positive pregnant women and their infants in rural South Africa. METHODS AND ANALYSIS: This cost-effectiveness analysis (CEA) protocol complies with the Consolidated Health Economic Evaluation Reporting Standards 2022 checklist. A societal perspective will be chosen.The proposed methods will determine the cost and efficiency of implementing the intervention as per the randomised control trial protocol, as well as the cost of replicating the intervention in a non-research setting. The costs will be calculated using an appropriately adjusted version of the Standardised Early Childhood Development Costing Tool.Primary health outcomes will be used in combination with costs to determine the cost per improvement in maternal perinatal depression at 12 months postnatal and the cost per improvement in child cognitive development at 24 months of age. To facilitate priority setting, the incremental cost-effectiveness ratios for improvements in child cognitive development will be ranked against six other child cognitive-development interventions according to Verguet et al's methodology (2022).A combination of activity-based and ingredient-based costing approaches will be used to identify, measure and value activities and inputs for all alternatives. Outcomes data will be sourced from the RCT team. ETHICS AND DISSEMINATION: The University of Oxford is the sponsor of the CEA. Ethics approval has been obtained from the Human Sciences Research Council (HSRC, #REC 5/23/08/17), South Africa and the Oxford Tropical Research Ethics Committee (OxTREC #31-17), UK.Consent for publication is not applicable since no participant data are used in this protocol.We plan to disseminate the CEA results to key policymakers and researchers in the form of a policy brief, meetings and academic papers. TRIAL REGISTRATION DETAILS: ISRCTN registry #11 284 870 (14/11/2017) and SANCTR DOH-27-102020-9097 (17/11/2017).