Following Roux-en-Y gastric bypass surgery, measurements of weight regain as a percentage of maximum weight lost were most strongly associated with clinical outcomes when compared with alternative ways of measuring weight regain, according to study results published in JAMA.

The investigators of this prospective cohort study sought to characterize weight regain measures after participants reached their lowest weight following bariatric surgery and to analyze associations between weight regain measures and clinical outcomes.

The study sample included 1406 adults who underwent Roux-en-Y gastric bypass surgery at 10 hospitals between March 2006 and April 2009. Researchers measured the participants’ weight within the 30-day period prior to surgery, 6 months after surgery, and annually through January 2015 (median follow-up, 6.6 years). Weight regain was calculated using 8 dichotomous measures and 5 continuous measures (increase in kilograms, increase in body mass index [BMI], as a percentage of presurgery weight, as a percentage of nadir weight, and as a percentage of maximum weight lost). Clinical outcomes including progression of diabetes, hyperlipidemia, and hypertension; decline in quality of life (physical and mental); and satisfaction with surgery were compared in relation to weight regain measures using model fit, statistical significance, and magnitude of association.

Median age of participants was 47 years, and median presurgery BMI was 46.3; the majority of the study sample was female (80.3%) and white (85.6%). Median time for weight nadir was 2 years after Roux-en-Y gastric bypass surgery, and the median percentage of maximum weight lost was 37.4% of presurgery weight. The rate of weight regain was highest in the year after reaching nadir weight, but it continued to increase throughout the follow-up period. 

Percentage of patients who regained weight differed depending on the threshold used; for example, 5 years after reaching nadir weight, 43.6% regained ≥5 BMI points, 50.2% regained ≥15% of nadir weight, and 67.3% regained ≥20% of maximum weight lost. The percentage of maximum weight lost showed the strongest association between weight regain and all outcomes except hyperlipidemia, which was more strongly associated with BMI measurements. Of dichotomous measures, regain of ≥20% of maximum weight lost performed best overall as a measure of most clinical outcomes.

Measures that quantified weight regain as a percentage of maximum weight lost had the strongest association and best fit with clinical outcomes, including progression of diabetes, hypertension, decline in quality of life, and satisfaction with surgery. These results may inform standardization of weight regain measures in future bariatric studies.

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King WC, Hinerman AS, Belle SH, Wahed AS, Courcoulas AP. Comparison of the performance of common measures of weight regain after bariatric surgery for association with clinical outcomes [published online October 16, 2018]. JAMA. doi:10.1001/jama.2018.14433