Content validity of the illness perceptions questionnaire - revised among people with type 2 diabetes: A think-aloud study

Objectives: to access the cognitions of adults with type 2 diabetes whilst completing items on the Illness Perceptions Questionnaire Revised (IPQ-R). To determine whether these cognitions are congruent with the meaning of items and subscales as interpreted by researchers and clinicians using the IPQ-R and to identify the nature and extent of problems that individuals experience when completing the IPQ-R. Design: participants (n=36) were recruited from a primary care diabetes clinic and a hospital diabetes clinic. They were asked to complete the IPQ-R using a think-aloud' methodology. Main outcome measures: transcripts were analysed to identify instances where participants expressed problems with item completion, or where there was inconsistency between verbal and written responses. Results: the most problematic subscales were those of personal control' and consequences'. Conclusion: generally, participants found the IPQ-R unproblematic. However, participants had problems with the concept of cure' and symptoms' in the context of type 2 diabetes, and with the negative phrasing used in some items. These findings have important implications for the interpretation of IPQ-R scores, particularly when the IPQ-R is used as the basis for individualised interventions among people with type 2 diabetes.