Background: All patients undergoing gastric bypass surgery at this institution are recommended to achieve a goal of 10% total body weight (TBW) loss prior to surgery. The objective of this study was to determine whether preoperative TBW correlated with 3- and 4-year weight loss outcome.
Methods: This study was conducted prospectively at a large teaching hospital. All adult patients with 3- and 4-year follow-up data since the start of the study in 1998 to September 2007 were included. All data are expressed as mean +/- SD. Pairwise correlation and ordinary least squares regression analysis was used to determine the strength of association between preoperative TBW loss and weight loss at 3 and 4 years.
Results: One hundred fifty patients (120 females), age 45.3 +/- 8.9 years, were included. Their body mass indexes (BMIs), preoperatively and after 3 years, were 52.2 +/- 9.8 and 35.4 +/- 8.2 kg/m(2), respectively. There was a significant correlation between preoperative and 3-year TBW lost (9.5 +/- 6.8% vs 31.9 +/- 11.7%, r = 0.302, p = 0.0002) and between excess body weight (EBW) lost preoperatively and after 3 years (16.1 +/- 11.3% vs 55.1 +/- 20.2%, r = 0.225, p = 0.006). Ninety five patients had follow-up data available at 4 years. Their mean preoperative BMI was 52.6 +/- 9.7 kg/m(2) and decreased to 37.5 +/- 9.0 kg/m(2). The TBW loss prior to and after surgery (10.0 +/- 6.5% vs 29.4 +/- 11.5%) was significantly correlated (r = 0.247, p = 0.015). The EBW loss preoperatively and after 4 years correlated positively (17.1 +/- 11.1% vs 50.8 +/- 19.8%, r = 0.205, p = 0.046).
Conclusion: There is a significant correlation between weight loss attained preoperatively and sustained weight loss at 3 and 4 years.