Abstract
Severe acute malnutrition (SAM) affects 12.2 million children globally. Integrating a water, sanitation and hygiene (WASH) kit in outpatient SAM treatment can improve recovery rates by preventing WASH-related diseases and complications, but its cost at scale remains unknown. This study estimates the cost of integrating a WASH kit, composed of chlorine-based water treatment, safe water storage with a lid, soap, and a hygiene promotion component into Senegal's national protocol for treating uncomplicated SAM. This costing study was nested within the TISA randomised controlled trial, which evaluated the addition of a WASH component to standard SAM treatment for children aged 6-59 months. Cost data were collected from 660 participants enroled between December 2020 and December 2021. We took a societal perspective and used a micro-costing approach to estimate direct medical, non-medical and indirect costs. The WASH component led to a 2021 international $105.32 additional cost per child treated, with the WASH kit, transportation and management representing $33.03. Sensitisation to hygiene and water treatment cost $13.46 at health posts and $29.63 for two at-home visits. No additional out-of-pocket expenses were incurred by households, but $1.58 in opportunity costs (income loss) was observed. Human resources were the main cost driver for the WASH component, exceeding the human resources for standard SAM treatment. The total societal cost per child treated was $338.77, ranging from $238.09 to $517.29 in sensitivity analysis, with the SAM treatment representing 69% ($233.40) of this total cost. The main expense for this component was Ready-to-Use-Therapeutic Food (RUTF) ($154.39). The absence of additional costs for households induced by the WASH component is encouraging, as it suggests that it would not represent an obstacle to integration into the national protocol. We produced a robust and comprehensive cost estimate for integrating a WASH kit and hygiene promotion into Senegal's SAM treatment protocol. This increased the treatment cost by 45% which was lower than estimates from a previous study. Results inform budget planning and support future cost-effectiveness analyses of integrating WASH interventions into SAM protocols.