Evaluating the Illness Perception Questionnaire on patients with chronic kidney disease in Sweden

Scand J Caring Sci; 2012; 26; 474–484 Evaluating the illness perception questionnaire on patients with chronic kidney disease in Sweden Background: The Revised Illness Perception Questionnaire (IPQ‐R) measures illness perception according to the Common Sense Model of Self‐Regulation. Illness perception relates to coping, health management, treatment outcomes and health‐related quality of life. IPQ‐R has been used in many contexts. However, there is yet no Swedish version evaluated for validity, reliability and usability in the context of a Swedish, adult population with Chronic Kidney Disease (CKD). Objectives: To evaluate usability and psychometric properties of a Swedish translation of IPQ‐R on a group of adults in different stages of CKD. Methods:  Usability evaluation was carried out through cognitive interviews and psychometrics was assessed by internal consistency, test‐retest, inter‐correlations, correlations to health‐related quality of life and coping and testing for concurrent validity. Results: Content validity was strongly supported, but an uncertainty assessing symptoms attributed to CKD was indicated. All dimensions showed internal consistency, except the treatment control dimension. The IPQ‐R showed good stability over time except the personal control dimension. Most IPQ‐R dimensions distinguished illness representations between groups of different disease stages and symptom burden. The most supported IPQ‐R dimensions for inter‐correlations and convergent validity were identity, timeline cyclical, consequences and emotional representations. Conclusions: The evaluation of the Swedish version of IPQ‐R on patients with CKD showed support for construct validity, except for the dimensions controllability, illness coherence and timeline, which were less supported. These dimensions should therefore be interpreted with care in CKD patients. There is a need to capture uncertainty regarding illness identity. IPQ‐R should be interpreted with care in earlier stages of CKD or if few symptoms are reported. IPQ‐R may be applicable and useful as a tool in nursing practice to support healthy behaviour as well as assessing clinical interventions in patients with CKD.