Male gender is a predictor of morbidity and age a predictor of mortality for patients undergoing gastric bypass surgery

Abstract

Purpose: To determine preoperative risk factors predictive of adverse outcomes after gastric bypass surgery.

Summary background data: Gastric bypass results in sustained weight loss for seriously obese patients, but perioperative complications can be formidable. Preoperative risk assessment is important to establish the risk-benefit ratio for patients undergoing these operations.

Methods: Data for 10 risk factors predictive of adverse outcomes were collected on 1,067 consecutive patients undergoing gastric bypass surgery at the UCLA Medical Center from December 1993 until June 2000. Univariate analyses were performed for individual risk factors to determine their potential significance as predictors for complications. All 10 risk factors were entered into a logistic regression model to determine their significance as predictors for complications. Sensitivity analysis was performed.

Results: Univariate analysis revealed that male gender and weight were predictive of severe life-threatening adverse outcomes. Multistep logistic regression yielded only male gender as a risk factor. Male patients were heavier than female patients on entry to the study, accounting for weight as a potential risk factor. Patients older than 55 years had a threefold higher mortality from surgery than younger patients, although the complication rate, 5.8%, was the same in both groups. Sensitivity analysis demonstrated that the risk for severe life-threatening adverse outcomes in women increased from 4% for a 200-lb female patient to 7.5% for a 600-lb patient. The risk increased from 7% for a 200-lb male patient to 13% for a 600-lb patient.

Conclusions: Large male patients are at greater risk for severe life-threatening complications than smaller and/or female patients. Risk factors thought to be predictive of adverse outcomes, such as a history of smoking or diabetes, proved not to be significant in this analysis. Older patients had the same complication rate but a threefold higher mortality, suggesting that they lack the reserve to recover from complications when they occur.

Figure 1. Sensitivity analysis of the effect of gender and weight on the risk of adverse events for patients undergoing Roux-en-Y gastric bypass surgery. The probability of adverse events is represented on the ordinate and weight on the axis of the graph. For a 200-lb women, the risk of developing complications is slightly less than 4% and rises to 12% at 900 lb. The complication risk is higher for men at each weight and rises more steeply for men compared to women as weight increases. A 200-lb man has a 6.5% risk of complications that increases to 20% at 900 lb.