Reliability and Validity of the Duke Activity Status Index in Bariatric Surgery Individuals Living with Obesity: Insights into Prognostic Value

Background Obesity is a global health issue that complicates surgical outcomes, particularly in bariatric/metabolic surgery candidates. Assessing functional capacity is critical for optimizing preoperative planning and postoperative care. The Duke Activity Status Index (DASI) is a simple, self-administered questionnaire that estimates functional capacity based on daily activities. This study evaluates the reliability and clinical applicability of the DASI as an alternative to the 6-min walk test (6-MWT) for bariatric/metabolic surgery individuals living with obesity. Methods This cross-sectional study included 126 individuals who are candidates for bariatric/metabolic surgery. Participants completed the DASI and 6-MWT. Test-retest reliability was assessed using intraclass correlation coefficients (ICCs), and validity was evaluated through correlations with 6-MWT results. The agreement was measured using the standard error of measurement (SEM) and minimal detectable change (MDC). Results The DASI demonstrated excellent internal consistency (Cronbach's alpha = 0.86) and test-retest reliability (ICC = 0.97, 95% CI: 0.96-0.98). A strong correlation was observed between DASI and 6-MWT scores (r = 0.603; p < 0.001). ROC analysis showed an optimal cut-off score of 24.1 (AUC = 0.836), with 72.2% sensitivity and 74.1% specificity. The SEM and MDC values were 2.36 and 6.54 points, respectively. Conclusions The DASI is a reliable, accessible tool for bariatric surgeons to assess functional capacity in candidates for bariatric/metabolic surgery. Its simplicity, strong correlation with performance-based measures, and minimal resource requirements make it ideal for preoperative evaluations, particularly in resource-limited settings.