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Prediction rule estimated all-cause mortality risk before bariatric surgery
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Factors other than BMI play a vital role in the prediction of death in patients who are eligible for bariatric surgery; type 2 diabetes in particular is the most important predictor of mortality, researchers suggest.
All-cause 10-year mortality was 2.1% (n=330) among a cohort of more than 15,000 patients, according to researchers.
“Our results challenge conventional wisdom emphasizing the importance of BMI as a prognostic indicator for mortality in individuals eligible for bariatric surgery and, of equal import, the practice of using BMI as a surrogate for long-term prognosis,” Raj S. Padwal, MD, MSc, of the department of medicine at the University of Alberta and Alberta Diabetes Institute in Canada, and colleagues wrote.
Raj S. Padwal
Data from the United Kingdom General Practice Research Database was used to identify patients who met contemporary eligibility criteria for bariatric surgery (BMI ≥35 alone, or 30 to 34.9 with an obesity-related comorbidity). Ultimately, 15,394 patients aged 18 to 65 years (mean age, 46.9 years; BMI, 36.2; 62.2% women) were included to determine a simple prediction rule for all-cause mortality in patients eligible for bariatric surgery.
According to data, the final prediction model accounted for the following:
- Age (OR=1.09; 95% CI, 1.07-1.10);
- Type 2 diabetes (OR=2.25; 95% CI, 1.76-2.87);
- Current smoking (OR=1.62; 95% CI, 1.28-2.06) and;
- Male sex (OR=1.5; 95% CI, 1.2-1.87).
Further, the model demonstrated a C statistic of 0.768, according to data. Model discrimination or calibration did not improve, despite the significant predictive nature of BMI (OR=1.03; 95% CI, 1.01-1.05). The clinical prediction rule scored all-cause mortality based on a 4-variable scale (range: 0.2% for tier 1 to 5.2% for tier 4), demonstrating an individual risk calculation, according to data.
“Regardless, our findings call into question current practices, such as the inordinate emphasis placed on BMI increments of 5.0 embedded in contemporary eligibility criteria,” researchers wrote.
Disclosure: Padwal reports support by an alternative funding plan from the Government of Alberta and the University of Alberta. See the study for a full list of all other relevant financial disclosures.