A cost effectiveness analysis of the nutritious eating with soul study

ABSTRACT

PURPOSE Historically, African Americans (AA) have been underrepresented in nutrition-related behavioral research despite their disproportionate higher risk of cardiovascular disease (CVD). The Nutritious Eating with Soul (NEW Soul) Study is one of the first of its kind to recruit an AA only study group to examine CVD prevention via a clinical trial to examine changes in CVD risk factors across two cohorts who are randomly assigned to a plant-based, soul food vegan diet or low-fat omnivorous (omni) diet. The purpose of cost effectiveness analysis (CEA) is to inform clinical and policy decisions and the costs of interventions that society is willing to pay for. However, few studies have examined the cost effectiveness of behavioral interventions for AA adults. The purpose of this study was to evaluate the cost effectiveness of the nutrition and behavior change interventions of the NEW Soul Study, from a societal perspective, by examining direct costs to deliver the intervention, and indirect costs reported by participants associated with intervention adherence. METHODS Primary data were collected from AA adults (n=105) between the ages of 18-65 from the Midlands SC region, who enrolled in the NEW Soul Study, across two cohorts, and were identified as having overweight or obesity (BMI 25-49.9 kg/m2). Upon completion of baseline assessment of weight, and other laboratory measures, participants were randomized to follow a vegan or low-fat omni diet. A cost effectiveness analysis (CEA) of this randomized control trial is based on one-year outcomes collected in April 2019 for Cohort 1 and June-July 2020 for Cohort 2. An incremental cost effectiveness ratio (ICER) over the one-year study period was calculated based on the intervention (direct) and societal (indirect) costs and weight loss. Total Costs = Costs to deliver the intervention (ingredients for cooking demonstrations, meals) + participants' average cost of weekly groceries + average weekly costs of dining out. Quality adjusted life year (QALY) was calculated based on Short Form-12 survey responses that were collected at baseline and one year. Variations in weight loss between cohorts 1 and 2 before COVID-19 and during COVID-19 were assessed using a difference-in-difference (DD) study design. RESULTS The incremental cost effectiveness ratio (ICER) was $2,888.57 per pound of weight loss. The results fall within quadrant II of the cost effectiveness plane which indicates that the vegan diet group, as compared to the omni diet group was more cost effective, as participants in that diet group experienced greater weight loss in addition to the intervention costing less. Results from the least squares means estimate from DD models (adjusted for covariates) reveal that both diet groups experienced some gains in QALY from baseline to 12 months (omni baseline = 0.7889;omni 12 months= 0.804;vegan baseline =0.8027;vegan 12 months = 0.808), however there was no statistically significant DD in QALY between diet groups (Pr > t = 0.6485). Pre-COVID, Cohort 1 participants lost an average of 10.2 pounds at 12 months from baseline. During COVID, Cohort 2 participants lost an average of 3.7 pounds at 12 months from baseline. The difference-in-differences in weight loss pre-COVID and during COVID by diet group revealed a statistically significant change in weight loss at 12 months compared to baseline between cohorts 1 and 2 for the vegan diet group (p=0.0408). Pre-COVID (C1), the vegan diet group lost an average of 11 pounds. During COVID (C2), the vegan diet group lost an average of 3.47 pounds.CONCLUSIONS The vegan diet intervention produced clinically relevant weight loss at a lower cost and was therefore cost-effective. Both diet groups experienced similarly minimal gains in QALYs and the DD in QALYs between the vegan and omni groups was not statistically significant. (PsycInfo Database Record (c) 2022 APA, all rights reserved)