Assessment of interventional results based on patient-reported outcomes brings greater understanding of patients’ value judgments of therapeutic effectiveness, and in turn requires development of accurate psychometric instruments1. Though patient-reported outcome measures are very important for clinical practice, we cannot measure the function or disability of patients directly. It is absolutely important, therefore, to obtain the information on functional status, health-related quality of life (HRQOL), and other related data such as patients’ values and perceptions, through valid and reliable psychological assessments2.
How can we measure a patient’s health condition? “Measuring health” or “measuring disease” are necessary steps in outcome research. A patient-centered questionnaire is a widely used method to collect necessary information from subjects with a targeted condition. It is a core procedure to measure HRQOL with such an assessment. And it is essential to assess the difference in the patient’s condition before and after medical intervention, to determine its effectiveness. This is the key reason we must understand the psychometric principles.
Parkes and colleagues, in this issue of The Journal, discuss the sensitivity to change of pain measures in knee osteoarthritis (OA)3. They conducted a comparative study to investigate the increased sensitivity to change of combining outcomes compared to single measures of pain3. They have previously published an article focused on the same topic4.
How can we manage the number and content of outcome items to sharpen our measuring aim? When applying a psychometric scale to a certain condition, the process of selecting outcome items for research is a very important and interesting topic. A comprehensive approach means many items could cover a wide range of conceptual constructs, but the weakness is in the feasibility, or the statistical handling needed to …
Address correspondence to Dr. M. Akai, Graduate School, International University of Health and Welfare, 4-1-26 Akasaka, Minato-ku, Tokyo 107-8402, Japan. E-mail: akai-masami{at}iuhw.ac.jp