A Retrospective Study on the Pre-Operative Demographic, Behavioral, and Medical Predictors of Weight Loss in Patients Undergoing Laparoscopic Roux-en-Y Gastric Bypass

Matthew D Cooper, MD, Kathleen Kromer-Baker, PhD, That N Tran, MD, Maria Chun, PhD, Racquel S Bueno, MD, Cedric Lorenzo, MD. University of Hawaii


Multiple studies have demonstrated the efficacy of bariatric surgery in producing long term weight loss and resolution of medical comorbidities. Success after laparoscopic roux-en-y gastric bypass (LRYGB) is usually defined as a 50% or greater loss of excess body weight (EWL) at 1 year after surgery. Failure of a patient to achieve expected weight loss after gastric bypass is a frustrating and difficult problem for both patients and surgeons. If a better method of predicting a patient's potential for success or failure were available then pre- and post-operative interventions could be instituted to optimize weight loss efforts. This study aims to determine the factors that would identify patients most likely to benefit from surgery in order to optimize resource allocation, manage patients’ expectations, and avoid exposing patients unlikely to benefit from surgery to its inherent risks.


This study involved a retrospective chart review of 373 patients who underwent LRYGB from January 1, 2006 to December 31, 2009. Within this group, 202 were excluded for failure to attend adequate medical follow-up or incomplete demographic data. The final sample consisted of 171 participants. Variables were analyzed using linear and multivariate regression. Covariates were additionally tested for associations with %EWL using quantile regression, adjusted for gender, age, original BMI, and Caucasian ethnicity.


Factors significantly predictive of greater %EWL included Caucasian ethnicity, lower initial BMI, less prior alcohol use, and lack of dyslipidemia. Surprisingly, having a greater number of antihypertensive medications, presence of dyspnea of exertion, and obstructive sleep apnea were also predictive of greater %EWL after LRYGB. Increased preoperative pain and select health conditions were associated with less successful %EWL. These conditions included metabolic syndrome, diabetes, dyslipidemia, fasting hyperglycemia, anxiety, pain, gout, and kidney disease.


Results show that certain demographic characteristics and health conditions can positively or negatively affect patient outcomes after LRYGB. These associations may be used to further improve patient selection, manage patient’s expectations, direct preoperative psychological and medical therapy, and improve postoperative patient care. However, further study is needed to explain why a patient’s specific profile would positively or negatively affect their weight loss after LRYGB.

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