Validation of the Michigan Bariatric Surgery Collaborative outcomes calculator in a Hispanic population.

Background: The Michigan Bariatric Surgery Collaborative (MBSC) has developed an app that calculates outcomes, to include predicted weight loss and venous thromboembolism rates. The app is called Weigh the Odds. This app provides an important method for discussing outcomes with patients.

Objective: We sought to determine the validity of the MBSC outcomes calculator in a Hispanic population.

Methods: Community practice in Texas. Methods: A community practice with a large percentage of Hispanic patients was used to validate the MBSC calculator. The correlation coefficient was calculated. A chi-square test was used to compare quantitative variables between the operation types. Lin's concordance correlation along with the Bland-Altman plot were performed to estimate the level of agreement between actual and expected weights at 1 year.

Results: Two hundred seventy-six patients met the eligibility criteria and were included in the study. The average body mass index (BMI) at the time of initial bariatric surgery was 45.2 kg/m2 (standard deviation [SD], 6.68). One hundred seventy-seven patients underwent sleeve gastrectomy (SG), and 99 patients underwent Roux-en-Y gastric bypass (RYGB) as their initial bariatric operation. The mean actual weight at 1 year for the entire cohort was 90.8 kg (SD, 19.6), while the mean expected weight was 89.2 kg (SD, 16.9), leading to a mean difference of 1.6 kg. The concordance correlation coefficient of .80 (95% CI: .76-.84, P < .001) demonstrates a strong agreement between actual and expected weights at 1 year. There was a lower correlation coefficient for RYGB patients.

Conclusions: The concordance correlation coefficient demonstrated a strong agreement between actual and expected weights at 1 year. These findings validate the MBSC outcomes calculator in a Hispanic population.