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Early weight loss predicts longer-term success after bariatric surgery
In adults with obesity, weight loss 6 months after gastric bypass surgery predicts weight-loss success at 2 years, whereas early weight-loss failure does not necessarily predict poorer long-term outcomes, according to recent findings.
In a systematic review of 39 studies conducted in the United States, Europe, Australia, South America and the Middle East, researchers also found that psychosocial factors, such as depression, and the ability to adapt to certain behavioral changes after bariatric surgery may also be associated with weight-loss outcomes.
“Identifying predictors of successful weight and psychosocial outcomes is important to minimize rates of revisional surgery and the distress, disappointment and cost associated
with less-than-optimal results,” Leah Brennan, PhD, of the School of Psychology at Australian Catholic University in Melbourne, and colleagues wrote. “Potential preoperative predictors have shown few consistent relationships with bariatric surgery outcome. Postoperative variables that may be amenable to intervention have thus become an important area for research.”
Brennan and colleagues analyzed 39 studies of adults with a BMI of at least 30 kg/m² undergoing all types of bariatric surgery except short-term procedures. Predictors measured included postoperative weight trajectory and postoperative psychological, behavioral or psychosocial variables. Outcomes included weight or psychological, behavioral or psychosocial measures, including depression, eating behavior and quality of life; only studies that measured the predictor earlier to the outcome were included. Results were grouped as adjustable vs. nonadjustable surgeries; predictors were further grouped into early predictors (measured up to 6 months after surgery) and later predictors (measured at 12 months or later).
For patients who underwent adjustable bariatric surgery, such as gastric banding, six of seven tested relationships across four studies indicated that greater early weight loss in the first 6 months after surgery predicted greater weight outcomes at 24 months; early weight-loss failure, however, was not necessarily associated with failure at 24 months. In two studies, greater weight loss from 12 months after surgery was also related to better weight outcomes. Patients who experienced little weight loss at 18 months were unlikely to succeed.
For patients who underwent nonadjustable bariatric surgery, 28 of 34 relationships tested across 10 studies found that greater early weight loss in the first 6 months after surgery was associated with successful weight outcomes at 24 months; early weight-loss failure in the first 6 months was not always associated with weight-loss failure at 24 months. Greater weight loss at 12 months after surgery was also related to weight-loss success at 18 months, whereas weight-loss failure at 18 months after surgery often predicted weight-loss failure at 24 months.
Adherence to diet, physical activity and general rules after surgery was also associated with weight-loss success for patients who underwent nonadjustable bariatric surgery, according to researchers. For patients who underwent nonadjustable bariatric surgery, 12-month appointment attendance was related to greater 24-month and 36-month weight loss; high dietary adherence also predicted weight loss at 20, 40, 52 and 92 weeks.
Depression measured in the first 6 months after nonadjustable surgery predicted poorer weight-loss outcomes at 12 months, but not at 24 months, according to researchers. In addition, eating difficulties measured at 12 and 24 months were predicted by early depression and weight-related experimental avoidance, they wrote. Both measures also predicted poorer quality of life at 12 and 24 months.
“The most consistent relationship found in this review was that between better early weight loss and more successful midterm weight outcomes (up to 24 months),” the researchers wrote. “Early adaptation to the eating changes required after surgery may be associated with better weight loss, but the empirical support is less robust. Little research has tested whether postoperative adherence and psychological variables prospectively predict later outcome.”
The researchers recommended a “shift in focus,” from measuring concurrent predictors of bariatric surgery outcomes to research examining prospective predictors of outcomes, including increased attention to the prospective prediction of eating and psychosocial outcomes.
“There is far less research and no consistent evidence regarding the predictive validity of early adherence or psychosocial predictors of later weight outcome,” the researchers wrote. “Prospective predictors of eating, [quality of life] or weight maintenance/regain remain largely unexplored as do mediating and moderating relationships between predictors and outcome.” – by Regina Schaffer
Disclosure: The researchers report no relevant financial disclosures.