Objective: To develop a short form of the Arthritis Impact Measurement Scales 2 (AIMS2) questionnaire, preserving content validity as the priority criterion.
Methods: A 2-step reduction procedure was used: 1) Delphi technique, with 1 panel of patients and 1 panel of experts each selecting 1 set of items independently; and 2) nominal group technique, where members of both panels reached consensus on the final selection of items, using information derived from item analysis. Psychometric properties of the AIMS2-Short Form (AIMS2-SF) and AIMS2 were compared using data from a cohort of 127 rheumatoid arthritis patients who completed the AIMS2 twice prior to the initiation of methotrexate (MTX) treatment and 3 months post-initiation of MTX treatment.
Results: The 2 panels reached consensus on a 26-item AIMS2-SF (54.4% reduction from the AIMS2). Factor analysis showed preservation of the 5-component structure. Convergent validity (Physical and Symptom components with clinical variables: r = 0.24-0.59), test-retest reproducibility (intraclass correlation coefficient >0.7), and sensitivity to change at 3 months (standardized response mean 0.36-0.8, except Social Interaction component [0.08]) were very close to the values for the original AIMS2.
Conclusion: The AIMS2-SF is a shorter version of the AIMS2 (i.e., available in 2-page format) and has psychometric properties similar to those of the AIMS2.