Measuring the meaning of disability in rheumatoid arthritis: the Personal Impact Health Assessment Questionnaire (PI HAQ)

Open Access
Publisher Website
Google Scholar
Abstract
Background: Measurement of disability in rheumatoid arthritis is often used to support treatment decisions and outcome assessments, but is used without reference to the impact of disability on individual patients. Objective: To develop and validate a scale to measure individual values for functions, which is used to weight the level of an individual patient’s functional loss and thus calculate the personal impact of disability. Methods: In four linked studies, first the phraseology for values was explored to develop a stem question for the value scale couched in terms patients understand (face validity). Then short and long versions of the value scale were compared (content validity) and tests of internal consistency and short term reliability undertaken (criterion validity). Finally, the value scale was examined for long term reliability and agreement with expected variables (criterion and construct validity), after which personal impact scores were calculated and their construct validity examined. Results: Patients understand the concept of values, and a positively phrased stem question was developed for the value scale, for which a short version was reasonably equivalent to a long version. The value scale was reliable over one week (96% changed by Conclusion: This individualised personal impact scale should lend meaning to disability scores, improving the interpretation of clinical and research data.