title: What do people think about when they answer the Brief Illness Perception Questionnaire? A 'think-aloud' study.
abstract: OBJECTIVE
  The Brief Illness Perception Questionnaire (Brief IPQ) is a commonly used questionnaire that aims to assess patients' illness beliefs. There is, however, no direct information on how people interpret and respond to this questionnaire, nor on the nature and extent of problems people have when completing it. The present study describes the problems that patients encounter when completing the Brief IPQ.
  
  
  METHODS
  Cross-sectional observational study.
  
  
  METHODS
  A 'think-aloud' method was employed with two samples: 6 patients attending a preoperative exercise programme in secondary care, and 11 patients receiving physiotherapy in primary care.
  
  
  RESULTS
  In total, 88 problems were identified, mostly (N= 45) consisted of participants re-reading a question or stumbling in reading it. In 8 cases, participants misinterpreted a question. The pattern of findings was striking similar across the two samples. The questions about identity, personal control, illness coherence, and causal attributions yielded most difficulties (18, 16, 16, and 11 problems, respectively).
  
  
  CONCLUSIONS
  Given that the Brief IPQ assesses each construct with a single item, the number of problems people have with completing it is particularly problematic, and calls into question the content validity of this measure. Further developmental work with this questionnaire may be needed to better quantify and resolve the problems identified.
authors.affiliation: Academy of Physiotherapy, AVANS University of Applied Sciences, Breda, The Netherlands. ieke_van_oort@hotmail.com
authors.forename: L
authors.initials: L
authors.lastname: van Oort
authors.forename: C
authors.initials: C
authors.lastname: Schröder
authors.forename: D P
authors.initials: DP
authors.lastname: French
mesh_terms: D000223:Adaptation, Psychological; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D010361:Patients / Q000523:psychology*; D018434:Sickness Impact Profile; D011795:Surveys and Questionnaires; D013850:Thinking