Psychometric Evaluation and Interpretation of Health-Related Quality of Life Data

Determining if an HRQOL measure is adequate for research and clinical applications requires evaluating its psychometric properties, including reliability and validity. Reliability refers to the extent to which a measure yields a similar value each time it is administered, all other things being equal. Validity is the degree to which the measure reflects what it purports to measure rather than something else. Methods sections of articles need to summarize the evidence for the reliability and validity of selected scales. Conditions under which the study was conducted (e.g., method of administration, instructions given to subjects) as well as descriptive information (e.g., subject demographics) should be described. Longitudinal validity studies need to evaluate separately responsiveness to improvement versus decrement in the underlying condition. The authors conclude that attention to the psychometric characteristics of HRQOL instruments will help improve measurement of health outcomes in future research.