Clinical utility of the Fibromyalgia Impact Questionnaire is enhanced

August 1, 2009

Bennett RM, Bushmakin AG, Cappelleri JC, et al, Oregon Health and Science University, Portland, and other centers. Minimal clinically important difference in the fibromyalgia impact questionnaire. J Rheumatol. 2009;36:1304-1311.

In patients with fibromyalgia syndrome (FMS) who show moderate to severe impairment on the Fibromyalgia Impact Questionnaire (FIQ), a change of about 14% over 3 months probably is clinically important. A similar percentage change in stiffness also is likely to have clinical importance.

Bennett and associates analyzed data from 3 double-blind, randomized, placebo-controlled, parallel-group clinical trials of pregabalin in 2228 persons with FMS. The FIQ was completed at baseline and end point in all 3 studies, and the Patient Global Impression of Change (PGIC), a global assessment tool, was completed at end point. The investigators used the data to determine the lowest change in FIQ score (minimal clinically important difference [MCID]), indicative of a meaningful difference in FMS status.

The percentage change in the FIQ score in each PGIC category and the MCID for the FIQ total score were similar in each of the 3 studies. Overall, pooled across the 3 studies, the estimated MCID in the FIQ total score was 14.1%; the MCID in the FIQ stiffness item was 13.2%.

The authors noted that the results of these analyses should enhance the clinical utility of the FIQ in research and practice.