Effect of preoperative body mass index on weight loss after obesity surgery

Abstract

Background Prior studies suggest individuals with body mass index (BMI) above vs. below 60 kg/m2 show lower percentage of excess body weight loss (%EBWL) following bariatric surgery. Objectives 1. Test whether conclusions drawn about the effect of preoperative BMI on postoperative weight loss depend on the outcome measure; 2. Test for evidence of a threshold effect at BMI=60 kg/m2 and; 3. Test the effect from surgery to 12-month, relative to 12- to 36-month, follow-up. Setting Large University-affiliated hospital in New York. Methods Retrospective analyses of participants grouped according to preoperative BMI: 35–39.9 (n=232); 40–49.9 (n=1166); 50–59.9 (n=429); ≥60 (n=166). Results As anticipated, individuals with higher vs. lower preoperative BMI showed greater total body weight loss but lower %EBWL at all postoperative time points (all p’s<0.0005). However, these individuals also showed lower percentage of initial body weight loss (%IBWL) at all time points beyond 1 mo post-surgery (all p’s<0.0005). From 12- to 36-months, individuals with BMI: 35–39.9 showed 3.2±14.3 %IBWL (p<0.0001); 40–49.9 showed 1.0±8.9 %IBWL (p<0.0005); 50–59.9 showed −2.4±10.0 %IBWL (p<0.0005) and; ≥60 showed −3.6±11.5 %IBWL (p<0.0005). Overall F3,1989=20.2, p<0.0005. Conclusions Conclusions drawn about the effect of preoperative BMI may depend on the outcome measure. A dosage effect of preoperative BMI was apparent, with heavier individuals showing lower percentages of initial and excess weight loss, regardless of BMI above or below 60kg/m2. Finally, this effect was particularly apparent following the initial 12-month rapid weight loss phase, when less obese (BMI<50) individuals continued losing weight, while heavier individuals (BMI≥50) regained significant weight.

Obese patients lose weight independently of nutritional follow-up after bariatric surgery

“…It has been consistently reported that bariatric operations frequently lead to significant weight loss, which starts shortly after the surgical procedure, continues for some time and is thought to plateau for most individuals around 18 months after surgery, when maximal weight loss is reached. 9,[16][17][18][19][20][21] In our study, the GEE analysis suggested that the nadir of body weight loss occurs around the 4 th trimester after surgery, between the first and second years after surgery and this finding agrees with those previous reported.…”

“…On the other hand, Ochner et al 17 found that greater initial BMI were associated with worse postsurgical weight loss outcomes, but recommended caution when making comparisons, since results may vary, depending on the weight loss measure chosen and the time of postoperative period. They argue that postsurgical weight loss occurs at a relatively steady rate in the first 12 months after surgery, regardless of preoperative BMI, and shows great variability among BMI categories after 12-month follow-up.…”

Impact of preoperative body mass index on the final outcome after laparoscopic sleeve gastrectomy for morbid obesity

“…This might imply that the lower the preoperative BMI, the better are the results obtained by bariatric surgery and LSG in particular. This finding is concordant with the study by Ochner et al (27) reporting that the effect of preoperative BMI was apparent, heavier individuals showed lower percentages of initial and excess weight loss, and that this effect was particularly apparent after the initial rapid weight loss phase during the first year, when patients with BMI <50 continued losing weight, while patients with BMI ≥50 regained significant weight. Another cohort study reported significant weight loss and improvement of T2DM, hypertension and dyslipidemia after LSG in 78 patients whose BMI was less than 50 (28).…”

Bariatric surgery outcomes in black patients with super morbid obesity: a 1-year postoperative review

“…When compared to White patients, obese Black patients are known to have a higher prevalence of obesity-related comorbidities, including hypertension and type II diabetes mellitus [12][13]. While obesity is highest among Black (47.8%) and Hispanic (42.5%) populations, the majority of patients who undergo bariatric surgery are White (89%) [14]. Black patients also have higher rates of super morbid obesity at the time of surgery when compared to White patients [15][16].…”