The construct validity of the illness cognition questionnaire: the robustness of the three-factor structure across patients with chronic pain and chronic fatigue.

BACKGROUND The Illness Cognition Questionnaire (ICQ; Evers et al., J Consult Clin Psychol, 69:1026-1036, 2001) assesses three ways of cognitively evaluating the stressful and aversive character of a chronic illness: helplessness, acceptance, and perceived benefits. PURPOSE The purpose of this study was to evaluate the construct validity of the ICQ in individuals with chronic pain and patients with chronic fatigue. METHOD The ICQ was administered to 821 individuals with chronic pain and 295 patients with chronic fatigue. Confirmatory factor analyses were performed to assess the hypothesized three-factor structure, containing the factors "helplessness," "acceptance," and "perceived benefits." A multigroup analysis was performed to investigate the stability of the factor structure in both groups. RESULTS Results confirmed the three-factor structure in the two samples. The factor structure was invariant across individuals with chronic pain and chronic fatigue. CONCLUSION As the three-factor structure provided a good fit in both groups, we confirm the usefulness of the subscale scores in research and clinical practice.