Impact of Nutritional Support for Tuberculosis on Intermediate and Terminal Undernutrition and Treatment Outcomes (INSTITUT) study: a protocol for a quasi-experimental study to assess the impact of nutritional support on tuberculosis treatment outcomes in Benin and Togo.

Introduction: Undernourished persons with tuberculosis (TB) (PWTB) are at increased risk of mortality, treatment failure and relapse. Nutritional support for PWTB has the potential to mitigate the risk of undernutrition. However, given ethical concerns, well-powered randomised control trials of macronutrient support are unavailable to inform policymakers, clinicians and researchers about the impact of nutritional support. However, there is potential to understand the impact of macronutrient nutritional support through a natural experiment. Benin and Togo are neighbouring countries in West Africa. Benin's national TB programme currently provides all PWTB with nutritional support whereas Togo's national TB programme does not provide nutritional support to PWTB with drug-susceptible strains. Comparing treatment outcomes of PWTB treated in Benin and Togo can help us understand the impact of nutritional support for PWTB.

Methods And Analysis: We designed a programmatic, prospective cohort study to assess the treatment outcomes among persons with pulmonary tuberculosis under programmatic conditions. PWTB cared for in Benin served as the exposed populations and those in Togo served as control. We plan to enrol 1050 adult participants across two countries: 700 subjects from Benin and 350 from Togo. We did not alter nutritional services offered to PWTB for the purposes of this study. Participants will be identified by the National Tuberculosis Programs of each country through 13 basic management units and followed until 6 months after treatment completion. The outcome of interest is a composite of all-cause mortality, treatment failure and relapse. Additional secondary outcomes will assess the effects on the rate of sputum conversion, loss to follow-up, weight gain, quality of life and post-TB lung health using surveys and a 6 min walk test. We hypothesise that participants receiving nutritional support will experience fewer unfavourable outcomes, faster sputum clearance, improved weight gain and fewer persistent respiratory symptoms.

Ethics And Dissemination: This study has received approval from the Boston University Medical Campus and Boston Medical Center Institutional Review Board (H-43096). The study also received a favourable decision from the Benin Comité d'Ethique de la Recherche and approval from the Comité de Bioéthique pour la Recherche en Santé of Togo. Informed consent will be obtained from all study participants prior to their engagement in the research. Findings from the study will be disseminated via national and international conferences and through manuscript publications in peer-reviewed journals. Data can be made available upon request to the corresponding author.

Trial Registration Number: NCT06084715. Pre-results.