Am I on Track? Evaluating Patient-Specific Weight Loss after Bariatric Surgery Using an Outcomes Calculator

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Conference Proceeding

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Publication Title

Journal of the American College of Surgeons


Introduction: Individual weight loss outcomes after bariatric surgery can vary considerably. As a result, identifying and assisting patients who are not on track to reach their weight loss goals can be challenging.

Methods: Using a bariatric surgery outcomes calculator formulated by the Michigan Bariatric Surgery Collaborative (MBSC), 1-year predicted weight loss was calculated for patients who underwent primary sleeve gastrectomy and gastric bypass between 2015 and 2018 and also had a minimum of 3 follow-up weights reported (n = 658). Observed to expected (O:E) ratios were calculated for all patients and weight loss trajectories were compared between patients who met or exceeded their predicted weight loss calculation (O:E ≥1) to those who did not (O:E<1).

Results: Patients who did not meet their 1-year predicted weight loss (n = 237, mean O:E = 0.71) had a lower mean preoperative BMI (46.7 kg/m2 vs 48.5 kg/m2, p = 0.0079), were more likely to be black (13.9% vs 8.2%, p = 0.023) and had higher rate of hypertension (59.1% vs 48.9%, p = 0.0124) when compared with patients who either met or exceeded their weight loss prediction (n = 421,mean O:E = 1.14). Patients who did not meet their weight loss prediction also had less mean total body weight loss (19.8% vs 29.6%, p < 0.0001) and were noted to have a lower O:E ratio as early as 3 months after surgery (0.50 vs 0.58, p < 0.0001).

Conclusion: Using a bariatric-specific weight-loss calculator, individuals can determine if they are on track to meeting their predicted weight loss calculation as early as three months after surgery.





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