Page 117 - The efficacy and effectiveness of psychological treatments for eating disorders - Elske van den Berg

Chapter 6 117
cating more impulsivity. Internal consistency (Cronbach’s α = .83) and test-retest reli- ability (Spearman’s rho = .83) are high [48].
Depressive symptoms were assessed with the Dutch version of the Beck Depres- sion Inventory (BDI), a self-report questionnaire consisting of 21 items, with a higher score indicating a higher level of depressive symptoms. Internal consistency (Cron- bach’s α = .88) is high [49- 51].
Data analysis
Statistical analyses were performed using the IBM SPSS statistics program, version 19. Analysis of variance (ANOVA) was used for all variables except the nomi- nal variables, to compare the differences between <50% EWL and ≥50% EWL. For analyses comparing two nominal variables, a chi-square test was used (type of surgery, loss of control (LOC) over eating, previous psychological treatment, pre-op- erative super-obesity, gender and age at time of surgery) . There were statistically significant differences in the follow-up time after surgery between the groups, and the group means were therefore adjusted for confounders by entering follow-up time after surgery as a covariate. ANOVA assumptions were tested. In case of non-normal distribution, data were transformed through ANCOVA before statistical testing; this is indicated in the Results section. A Pearson’s R analysis was conducted to meas- ure the strength of the association between weight loss in the first six months and total weight loss after surgery. Multiple logistic regression analyses were conducted to identify variables that predicted less weight loss. The cut-off for significant mean differences between the groups was set at p < . 05.
Results
The mean age of all the participants was 47.52 (SD = 9.79) and the mean pre-oper- ative BMI was 46.76 kg/m2 (SD = 8.00). The average follow-up time post-operative was 3.16 years (SD = 2.83). Eighty-one percent of the participants (n = 105) met the criteri- on for successful weight loss; nineteen percent (n = 27) met the criterion for subopti- mal weight loss. The mean follow-up time after bariatric surgery was significantly longer in the suboptimal group (p = .003), with an average of 4.99 years (SD = 4.45; range 0.95 - 24.48 years), compared to the successful group, which was 2.72 years (SD = 2.09; range 0.76 - 15.54 years). A significant difference in distribution between <50% EWL and ≥50% EWL in the participants recruited through the Dutch eating disorder treatment center was found χ2(1) = 15.085, p < .001. In the total cohort of <50% EWL, 26% (7/27) was recruited through the treatment center.