Construct validity and temporal stability of the abridged 31-item Illness Behaviour Questionnaire

• Published in: Psychology & health 2014-05, Vol.29 (5), p.517-535
• Main Authors: Prior, Kirsty N., Bond, Malcolm J.
• Format: Article
• Language: English
• Subjects: abnormal illness behaviour; Adult; Aged; Asthma - psychology; chronic illness; Chronic Pain - psychology; construct validity; Diabetes Mellitus - psychology; Fatigue Syndrome, Chronic - psychology; Female; Humans; Illness Behaviour Questionnaire; Longitudinal Studies; Male; Middle Aged; Psychometrics; Reproducibility of Results; Surveys and Questionnaires; test-retest reliability; Time Factors
• ISSN: 0887-0446; 1476-8321
• DOI: 10.1080/08870446.2013.863885

Objective: Key psychometric information was sought for three newly derived dimensions from an abridged Illness Behaviour Questionnaire (IBQ-31): Affirmation of Illness (AI), Concern for Health (CH) and General Affective State (GAS). The construct validity of these scales was examined along with their test-retest reliability and long-term stability. Design: A longitudinal, observational study was conducted with 675 participants (general community members and those with either asthma, diabetes and chronic pain or chronic fatigue syndrome) providing self-report questionnaire data at baseline, with additional information sought at three (n = 483; 71.6%) and 12 months (n = 517, 76.6%). Main outcome measures: Construct validity of the IBQ-31 was explored using well-validated psychological measures of Symptom Attributions and Symptom Experience, Cognitive Distortion of Somatic Information and Illness Likelihood. Results: In general, AI, CH and GAS shared predictable empirical overlap with related psychological indices across the five samples. Adequate three-month test-retest reliability was evident, with greater score variability over 12 months. Conclusion: The IBQ-31 comprises three theoretically relevant dimensions which demonstrate relative short- and long-term stability for individuals with diverse illness experiences. Future investigations should explore the predictive validity of AI, CH and GAS, along with the potential value of 'cut-off' scores for clinical use.