Reliability and Validity of the Greek Version of Sickness Impact Profile Questionnaire

Abstract

Background:The objectives were to assess the validity and reliability of the Greek version of the Sickness Impact Profile (SIP-GR) questionnaire. Methods: SIP-GR was tested for test-retest reliability, internal consistency and validity in 90 participants (54.4% males and 45.6% females) with obesity, cardiac, pulmonary and musculoskeletal problems. The questionnaire was administrated twice by one examiner, within an interval of 1-week. During this period, participants with cardiac, pulmonary and musculoskeletal problems underwent 2-weekly physiotherapy sessions. Treatment related effects were considered in the analysis. Results: SIP-GR demonstrated an excellent internal consistency. The overall Cronbach's alpha for SIP-Total score >0.9, for SIP-Psychological was >0.8 and for SIP-Physical >0.9. The categories scores were all >0.5 except for Communication and Work category. Test-retest reliability for the total score was ICC=0.691 for all subjects, 0.562 for those that reported a subjective change in their health status due to treatment and 0.999 for those that reported no change in health status. Similar results were found for the Physical and Psychological component. Strong negative correlation was found between SIP-Gr total score and Short Form Health Survey SF-36 (SF-36) total score (r=-0.66), physical component of ) and between psychological component of SIP-GR and Mental health of SF-36 (r=-0.61) at the initial assessment. At reassessment the same correlations were moderate due to different treatment effects in the scores of the two questionnaires. Finally, minimum detectable change (MDC) was 4.6-5.5 points for the overall score, 6.4-7 for Physical component and 3.5-4.9 for psychosocial component, at initial assessment and re-assessment respectively. Conclusion: SIP-GR has shown to be valid and reliable for the assessment of patients with cardiac, pulmonary, musculoskeletal diagnosis and obesity. Further studies should assess its ability to identify clinically meaningful changes.