P229 Evidence of content validity and psychometric properties of SF-36 for measuring health-related quality of life of patients with Crohn’s disease
A. Yarlas1, M. White1, M. Ingham2, D. Naessens*3, C. Han3
1Optum, Lincoln, Nebraska, United States, 2Janssen Scientific Affairs, LLC, Horsham, Pennsylvania, United States, 3Janssen Pharmaceutica NV, Beerse, Belgium
A literature review and cognitive debriefing interviews were conducted to assess the adequacy of evidence for the SF-36® Health Survey (SF-36) as a valid and reliable instrument for measuring health- related quality of life (HRQOL) in patients with Crohn’s disease (CD) in clinical trials.
A literature search of several medical databases (eg, Medline and Ovid) used search terms for variations of SF-36 and Crohn’s disease in the title or abstract of English language publications within the past 20 years. Amongst 327 identified abstracts, 76 full-text articles were reviewed, of which 34 articles were selected for data extraction based on appropriateness of content. Evidence of content validity and psychometric properties was evaluated based on the criteria specified in the FDA Guidance for Industry, ‘Patient-Reported Outcome Measures: Use in Medicinal Product Development to Support Labeling Claims’. In addition, a cognitive debriefing study of the SF-36 was conducted via qualitative interviews with 16 patients with moderate-to-severe CD.
Concept elicitation studies supported content validity, where concepts reported by patients on the effect of CD on their daily functioning and well-being were well aligned with concepts measured by the SF-36 and were not redundant with disease-specific measures in HRQOL in CD. Cognitive debriefing interviews confirmed the relevance and comprehensiveness of all concepts covered by SF-36, as well as appropriateness of the instructions, response scales, and recall period. Evidence showed that SF-36 scores for patients with CD were consistently lower than normative scores from the general population and similar to patients with other chronic conditions such as diabetes and asthma. The literature supported the ability of SF 36 scales and summary scores to detect clinically meaningful change in HRQOL in patients with CD receiving effective treatment. Convergent and discriminant validity were demonstrated by the evidence that SF-36 scores highly correlated with scores of other HRQOL measures in patients with CD and clinically meaningful differences were found on all SF-36 scales when comparing patients with CD across levels of disease activity. Reported findings from samples of patients with CD included evidence for good internal consistency reliability (Cronbach’s alphas ranging from 0.72 to 0.90) and good test-retest reliability (intraclass correlation coefficients ranging from 0.72 to 0.89) for all 8 SF-36 scales.
The comprehensive literature review and cognitive debriefing study demonstrated evidence for content validity and strong psychometric properties of SF-36 when used in patients with CD across different disease activities.