More than 8 percent excess weight loss before bariatric surgery improves post-surgery weight loss
Patients who lose ≥8 percent of their excess weight via a 1-month-long surgeon-recommended low-calorie diet prior to undergoing primary vertical sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB) have a greater rate of excess weight loss up to 1 year following the procedure, a recent study found.
“Based on these data, pre-operative weight loss of ≥8 percent excess weight while following a 4-week low-calorie diet is associated with a significant increase in postoperative [percentage] excess weight loss over 12 months,” said the researchers.
“We believe this study will be helpful to individual surgeons as they determine the optimal strategy for preparing patients for surgery, taking into consideration patient demographics, clinical characteristics, surgical risk, and access to surgery.”
Based on the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program database, 355 patients (mean age 45.4 years, 78.9 percent female, mean BMI prior to initiating diet 47.4 kg/m2) who underwent a 4-week-long low-calorie diet programme (1,200 kcal/day with the aim of losing ≥8 percent excess weight) immediately before undergoing SG (n=167) or RYGB (n=188) between January 2014 and January 2016 were divided into two groups: those who did or did not achieve ≥8 percent excess weight loss during the low-calorie diet programme.
Of these, 224 patients achieved the ≥8 percent excess weight loss (mean age 46.2 years, 74.6 percent female, mean BMI at diet programme end, 43.8 kg/m2) while 131 patients did not (mean age 44.2 years, 86.3 percent female, mean BMI at diet programme end, 47.7 kg/m2).
Patients who lost ≥8 percent of their excess weight before surgery had higher postoperative excess weight loss than their counterparts who did not lose ≥8 percent excess weight (42.3 percent vs 36.1 percent; p<0.001 at 3 months, 56.0 percent vs 47.5 percent; p<0.001 at 6 months, and 65.1 percent vs 55.7 percent; p=0.003 at 12 months). [J Am Coll Surg 2018;doi:10.1016/j.jamcollsurg.2017.12.032]
Absolute change in post-surgery BMI only differed between groups at 1-month post-surgery (3.7 vs 2.3 kg/m2 for patients who did vs did not achieve ≥8 percent excess weight loss; p=0.021).
Patients who achieved ≥8 percent weight loss presurgery also had a significantly shorter hospitalization period following surgery (mean, 1.8 vs 2.1 days; p=0.006) and a nonsignificantly shorter surgery time (median, 117 vs 125 minutes; p=0.061) than those who did not achieve the ≥8 percent weight loss target. The effects on surgery duration did not differ by type of surgery. There was also no difference between those who did or did not lose ≥8 percent weight presurgery in terms of readmission or reoperation rates.
“Currently, controversy exists for the optimal pre-operative dietary optimization of patients prior to bariatric surgery. On one side, insurance policies often mandate 6- or 12-month weight management programmes. This mandate is in direct contrast to many bariatric surgeons, who prefer to use short-term, calorie-restricted diets several weeks prior to surgery in order to optimize outcomes,” said study co-author Associate Professor John David Scott from the University of South Carolina School of Medicine, Greenville, South Carolina, US.
However, the researchers acknowledged that the 8 percent or higher presurgery weight loss target should function as a goal, but not necessarily a prerequisite, for bariatric surgery.
“[P]atients with obesity who weren’t able to achieve that 8 percent goal still had dramatic effects in terms of how much weight they lost and comorbidity resolutions,” said Scott.
Among the study limitations were the single-centre design, reliance on patient self-reports regarding adherence to diet, and short follow-up period, said the researchers, who called for further study into identifying the impact of low-calorie diet-related pre-operative weight loss on long-term outcomes.