Comparison of the Performance of Common Measures of Weight Regain After Bariatric Surgery for Association With Clinical Outcomes

Abstract

IMPORTANCE Estimates of weight regain following bariatric surgery vary widely. OBJECTIVE Describe weight regain following post-Roux-en-Y gastric bypass (RYGB) weight nadir, and compare common weight regain measures for association with clinical outcomes. SETTING Ten hospitals in six US cities: Portland, OR, Seattle, WA, Fargo, ND, Pittsburgh, PA, New York, NY and Greenville, NC. DESIGN AND PARTICIPANTS Adults undergoing bariatric surgical procedures entered a prospective cohort study between February 2006-February 2009 (N=2458) and completed pre-surgery, six month and annual assessments for up to seven years through January 2015. Participants who underwent RYGB and were followed ≥5 years with ≥5 weight measurements were included (83%; 1406 of 1703, excluding deceased/reversals). EXPOSURE Weight regain assessed by five continuous measures (kg, body mass index [BMI; kg/m2], % pre-surgery weight, % nadir weight and % maximum weight loss) and eight dichotomous measures (per established thresholds) were compared in relation to clinical outcomes based on statistical significance, magnitude of association and model fit. MAIN OUTCOME MEASURES Progression of diabetes, hyperlipidemia, and hypertension, and declines in physical and mental health-related quality of life, and satisfaction with surgery. RESULTS Medians (25th–75thpercentiles) are reported. Pre-surgery age was 47 years (38–55) and BMI was 46.3 (42.3–51.8). Most participants were female (80.3%) and white (84.9%). Follow-up was 6.6 (5.9–7.0) years. Maximum weight loss was 37.4% (31.6%−43.3%) of pre-surgery weight, occurring 2.0 (1.0–3.2) years post-surgery. The rate of weight regain was highest in the first year following weight nadir, but regain continued across follow-up, ranging from 9.5% (4.7%−17.2%) to 26.8% (16.7%−41.5%) of maximum weight lost, one to five years post-nadir. The % participants who regained weight depended on threshold (e.g., five years post-nadir, 43.6% regained ≥5 BMI points, 50.2% regained ≥15% of nadir weight and 67.3% regained ≥20% of maximum weight lost). Percentage of maximum weight lost vs. other continuous weight regain measures, had the strongest associations with, and best model fits for, all outcomes except hyperlipidemia, which had a slightly stronger association with regain in BMI. Of dichotomous measures, ≥20% of maximum weight lost performed best with all outcomes except hyperlipidemia and satisfaction (≥10 kg and ≥25% of maximum weight lost were superior, respectively). CONCLUSIONS Among a large cohort of adults who underwent RYGB, weight regain quantified as percentage of maximum weight lost performed better for association with most clinical outcomes than the alternatives examined. These findings may inform standardizing measurement of weight regain in studies of bariatric surgery.

Definitions of Long-Term Weight Regain and Their Associations with Clinical Outcomes

“…However, in the long-term, these results are not maintained in all patients. There is growing recognition that weight regain is a concern after bariatric surgery [3][4][5][6][7][8]. Weight regain has been associated with deterioration in HRQoL, the reemergence of type 2 diabetes and other comorbidities, and patients' opinion about surgery success [3,4,[9][10][11].…”

“…Estimates of the percentage of patients who regain a significant amount of weight vary widely [4][5][6][7][8]. In a systematic review among 16 studies, weight regain rates ranged from 19 to 87% for patients who underwent RYGB and sleeve gastrectomy (SG), while a systematic review among 21 studies found weight regain rates after SG ranged from 6 to 76% over variable follow-up periods ranging from 2 to 6 years [4,5].…”

“…Many different, arbitrary definitions of weight regain are currently found in the literature [10]. These definitions include, but are not limited to: Bany weight regain,^the percentage of total weight lost at nadir, the percentage of excess weight loss (%EWL), the percentage of weight change from nadir, or a minimum increase in kilograms [3,5,8,[13][14][15][16][17][18][19][20][21].…”

Assessment of self‐rated health 5 years after Roux‐en‐Y gastric bypass for severe obesity

“…Weight development from baseline through 5 years was reported by standard measures: percentage excess weight loss (%EWL), percentage excess BMI loss (%EBMIL), percentage total weight loss (%TWL) and change in BMI. Weight regain, from nadir weight occurring between 1 and 2 years after surgery to 5 years, was reported as change in BMI and percentage of maximum weight loss.…”

New Metrics to Assess Type 2 Diabetes after Bariatric Surgery: The “Time-Within-Remission Range”

“…Dyslipidaemia was based on the presence of fasting LDLc ≥ 160 mg/dL, HDLc ≤ 40 mg/dL, fasting triglyceride ≥ 200 mg/dL or active use of lipid lowering therapy [19]. Weight regain was calculated as the difference between the weight lost at nadir and the weight on the last observation expressed as percentage [20].…”