Sex and Race Factor into Weight Loss with Gastric Bypass

Dr. Ramsey M. Dallal said at the annual meeting of the American Society for Metabolic and Bariatric Surgery, "Long-term treatments of obesity are hampered by the fixed behaviors that induce obesity, the possibility of weight set points, and the ever-present exposure to high-calorie foods." "The treatments of obesity all have great variability in outcome."

In order to determine predictors of weight-loss failure after gastric bypass surgery, Dr. Dallal and his associate at the department of surgery at Einstein Healthcare Network, Philadelphia, reviewed the medical records of 1,256 gastric bypass patients who had a least 1 year of follow-up.

They separated patients into two groups: those who were above the 75th percentile in weight loss (success) and those who were below the 25th percentile in weight loss (failure). Multivariate logistic regression was performed to examine the impact of sex, race, age, initial weight, initial glycosylated hemoglobin (HbA_1c) level, and insurance type (Medicare/Medicaid vs. private insurance).

The mean preoperative body mass index of the 1,256 patients was 48.3 kg/m², their mean age was 42 years, and 82% were women. More than one-quarter of patients (27%) had diabetes, and the mean HbA_1c level was 6.6% in blacks and 6.3% in whites. The majority of patients (75%) had private insurance, 19% were on Medicare, and 6% were on Medicaid.

They reported that after a mean follow-up period of 665 days, the mean excess weight loss among all patients was 70%, and was significantly different between whites and blacks (72% vs. 63%, respectively), between those aged 65 years and older and those younger than age 40 (61% vs. 71%), and between men and women (62% vs. 71%). The calculated threshold estimated weight loss for the upper 75th and lower 25th percentiles was 82% vs. 57%, respectively.

Multivariate logistic regression analysis revealed the following independent predictors of weight-loss failure: being black (odds ratio, 3.1; P = .002), older (OR, 0.97; P = .001), or male (OR, 0.30; P less than .0005), and having a higher initial body weight (OR, 0.86; P less than .0005). Initial HbA_1c and insurance type were not independent predictors of weight-loss failure.

Certain limitations of the study, including the fact that the ideal body weight calculations used "may not necessarily be valid for all ethnicities. Also, we did not distinguish between primary weight-loss failures (those who never reached adequate weight loss) and those [who had] a secondary weight-loss failure (regain of lost weight)."

Presented at the annual meeting of the American Society for Metabolic and Bariatric Surgery, July 2012