Psychometric Characteristics of the Revised Illness Perception Questionnaire (IPQ-R) in People Undergoing Weight Loss Surgery.

The Illness Perception Questionnaire-Revised (IPQ-R) has been used extensively across many health conditions to measure patient illness and treatment perceptions. The constructs have an association with treatment adaptation and adherence which, in turn, are considered core factors involved in bariatric surgery outcome. This study examines the factorial validity and internal reliability of a modified (IPQ-R) in bariatric surgery candidates. After wording modifications, participants (N = 310) completed the IPQ-R as part of standard pre-surgery assessments. After removal of two items, confirmatory factor analysis (CFA) supported the original 7-factor solution of the Beliefs scale, with good to marginal subscale internal consistency. Exploratory factor analysis (EFA), with two items removed only partially supported the original 5-factor Causal Attributions scale. Internal consistency was unacceptably low for two subscales. Further research is needed to generate new items which better fit the IPQ-R to this population before research can explore the relevance of illness perceptions.