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

Methods

A community practice with a large percentage of Hispanic patients was used to validate the MBSC calculator. The correlation coefficient was calculated. Chi square test was used and to compare quantitative variables between the operation types, t-test was used. Lin's concordance correlation along with Bland-Altman level of agreement was estimated between actual and expected weights at one year.

Results

276 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 (SD, 6.68). 177 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 one 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 do a mean difference of 1.6 kg. The concordance correlation coefficient of 0.80 (95% CI : 0.76-0.84, p < 0.001) demonstrates a strong agreement between actual and expected weights at one 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 one year. These findings validate the MBSC outcomes calculator in a Hispanic population.