Prediction of long-term outcome after gastric bypass surgery

To investigate the predictability and sustainability of weight loss in gastric bypass (GBP) surgery after the first year, we conducted a 3-year follow-up of patients who had already been comprehensively studied preoperatively and after 1 year.

Preoperative data had been obtained for 131 morbidly obese patients on a 273-item interview and five psychological assessment instruments, and some of these data had been obtained again after a mean of 12.8 months. For this study, weight data were obtained on 79 patients at a mean of 3.2 years postoperatively.

Over the 1-3 year interval, mean simple weight loss and simple BMI decrease were essentially zero, compared with 45.61 kg and 16.52 respectively over the 0-1 year interval. Further, the 0-1 year and 1-3 year losses were uncorrelated. Optimal predictor variables for 1-3 year loss included three preoperative measures (expectation of increased self-confidence, amount of informational support, and total coping skills) plus functional eating behaviors after 1 year. Together they showed a multiple correlation of .55 with weight loss and .55 with BMI change. These predictors differed from the predictors of change over 0-1 year, and they continued to be significant after controlling for several preoperative characteristics.

The factors influencing long-term continuing weight loss after GBP are different from those influencing initial loss, and involve positive characteristics such as skills, information, and expectations. The results suggest the importance of actively teaching such skills during the first postoperative year.