title: Preoperative fat-free mass: a predictive factor of weight loss after gastric bypass.
abstract: Weight loss failure occurs in 8% to 40% of patients after gastric bypass (GBP). The aim of our study was to analyse the predictive factors of weight loss at 1 year so as to select the best candidates for this surgery and reduce the failures. We included 73 patients treated by laparoscopic GBP. We retrospectively analysed the predictive factors of weight loss in kilograms as well as excess weight loss in percentage (EWL%) at 1 year. The population was divided into tertiles so as to compare the sub-group with the highest weight loss with the sub-group with the least satisfactory results. The significantly predictive factors of a better weight loss in kilograms were male, higher initial weight (144 versus 118 kg, p = 0.002), a significant early weight loss and a higher preoperative percentage of fat-free mass (FFM%; p = 0.03). A higher FFM% was also associated with a better EWL% (p = 0.004). The preoperative FFM (in kilograms) was the principal factor accounting for the weight loss at 1 year regardless of age, gender, height and initial body mass index (BMI; p < 0.0001). There was a better correlation between FFM and weight loss (Spearman test, p = 0.0001) than between initial BMI and weight loss (p = 0.016). We estimated weight loss at 1 year according to initial FFM using the formula: 0.5 kg of lost weight per kilogram of initial FFM. The initial FFM appears to be a decisive factor in the success of GBP. Thus, the sarcopoenic patients would appear to be less suitable candidates for this surgery.
authors.affiliation: Department of Digestive Surgery and Bariatric Surgery, Hospices Civils de Lyon, Edouard Herriot Hospital, Université Claude Bernard Lyon 1, 5, Place d'Arsonval, 69 437, Lyon, France. maud.robert@chu-lyon.fr
authors.forename: Maud
authors.initials: M
authors.lastname: Robert
authors.forename: Elise
authors.initials: E
authors.lastname: Pelascini
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Disse
authors.forename: Philippe
authors.initials: P
authors.lastname: Espalieu
authors.forename: Gilles
authors.initials: G
authors.lastname: Poncet
authors.forename: Martine
authors.initials: M
authors.lastname: Laville
authors.forename: Christian
authors.initials: C
authors.lastname: Gouillat
mesh_terms: D000328:Adult; D001823:Body Composition; D015992:Body Mass Index; D005260:Female; D005500:Follow-Up Studies; D005602:France / Q000453:epidemiology; D015391:Gastroplasty / Q000379:methods*; D006801:Humans; D010535:Laparoscopy / Q000379:methods*; D008297:Male; D009767:Obesity, Morbid / Q000453:epidemiology / Q000601:surgery*; D011184:Postoperative Period; D011237:Predictive Value of Tests; D057234:Preoperative Period; D012189:Retrospective Studies; D016896:Treatment Outcome; D015431:Weight Loss