Objective: The goal of this project was to develop a more comprehensive and sensitive version of the Arthritis Impact Measurement Scales (AIMS).
Methods: AIMS scale items were revised, and 3 new scales were added to evaluate arm function, work, and social support. Sections were also added to assess satisfaction with function, attribution of problems to arthritis, and self-designation of priority areas for improvement. The new instrument was designated the AIMS2. A pilot test of format and content and a performance test of reliability and validity were carried out.
Results: Questionnaire completion times in a pilot study of 24 subjects averaged 23 minutes, and evaluations were positive regarding the instrument's length and ease of completion, and the subjects' willingness to complete serial forms and return them by mail. Measurement performance was tested in 408 subjects: 299 with rheumatoid arthritis (RA) and 109 with osteoarthritis (OA); 45 of these subjects completed a second AIMS2 within 3 weeks. Internal consistency coefficients for the 12 scales were 0.72-0.91 in the RA group and 0.74-0.96 in the OA group. Test-retest reliability was 0.78-0.94. All within-scale factor analyses produced single factors, except for mobility level in OA. Validity analyses in both the RA and the OA groups showed that patient designation of an area as a problem or as a priority for improvement was significantly associated with a poorer AIMS2 scale score in that area. Reliability, factor analysis, and validity results were consistent in age, sex, and education subgroups. Satisfaction was moderately correlated with level of function in the same health status area, and the satisfaction items formed a reliable scale. Responses to the arthritis attribution items showed that most dysfunction in this sample was due to arthritis.
Conclusion: The AIMS2 is a revised and expanded health status questionnaire with excellent measurement properties that should be useful in arthritis clinical trials and in outcomes research.