Psychometric evaluation of disordered eating measures in bariatric surgery patients

Bariatric surgery is considered the most effective weight loss intervention for obese persons. However, accurate assessment is essential to identify disordered eating that may impair achievement of optimal post-surgical outcomes. Measures of disordered eating are yet to be thoroughly psychometrically evaluated in bariatric surgery patients, therefore their utility is unknown.

Participants were 108 adults who completed psychological measures approximately 12 months after bariatric surgery. The fit of the original scale structures was tested using Confirmatory Factor Analysis (CFA) and alternative factor solutions were generated using Exploratory Factor Analysis (EFA). Reliability (internal consistency) and construct validity (convergent and divergent) were also assessed.

Eating Disorder Examination Questionnaire (EDE-Q), Questionnaire of Eating and Weight Patterns Revised (QEWP-R), Three Factor Eating Questionnaire (TFEQ) and Clinical Impairment Assessment (CIA).

CFA revealed none of the original disordered eating measures met adequate fit statistics. EFA produced revised scales with improved reliability (original scales α=0.47-0.94; revised scales α=0.76-0.98) and correlational analyses with measures of psychological wellbeing and impairment demonstrated adequate convergent validity. Reported prevalence of disordered eating behaviours differed between the EDE-Q and QEWP-R.

Psychometric evaluation did not support the use of the commonly used disordered eating measures in bariatric patients in their original form. The revised version of the EDE-Q replicates findings from recent research in bariatric surgery candidates. The alternate structures of the CIA and TFEQ suggest differences in the manifestation of disordered eating following surgery. Results suggest that revised measures are required to overcome the limitations of existing measures.