Minimum clinically important improvement and patient acceptable symptom state in pain and function in rheumatoid arthritis, ankylosing spondylitis, chronic back pain, hand osteoarthritis, and hip and knee osteoarthritis: Results from a prospective multinational study.

OBJECTIVE: To estimate the minimum clinically important improvement (MCII) and patient acceptable symptom state (PASS) values for 4 generic outcomes in 5 rheumatic diseases and 7 countries.
METHODS: We conducted a multinational (Australia, France, Italy, Lebanon, Morocco, Spain, and The Netherlands) 4-week cohort study involving 1,532 patients who were prescribed nonsteroidal antiinflammatory drugs for ankylosing spondylitis, chronic back pain, hand osteoarthritis, hip and/or knee osteoarthritis, or rheumatoid arthritis. The MCII and PASS values were estimated with the 75th percentile approach for 4 generic outcomes: pain, patient global assessment, functional disability, and physician global assessment, all normalized to a 0-100 score.
RESULTS: For the whole sample, the estimated MCII values for absolute change at 4 weeks were -17 (95% confidence interval [95% CI] -18, -15) for pain; -15 (95% CI -16, -14) for patient global assessment; -12 (95% CI -13, -11) for functional disability assessment; and -14 (95% CI -15, -14) for physician global assessment. For the whole sample, the estimated PASS values were 42 (95% CI 40, 44) for pain; 43 (95% CI 41, 45) for patient global assessment; 43 (95% CI 41, 44) for functional disability assessment; and 39 (95% CI 37, 40) for physician global assessment. Estimates were consistent across diseases and countries (for subgroups ≥20 patients).
CONCLUSION: This work allows for promoting the use of values of MCII (15 of 100 for absolute improvement, 20% for relative improvement) and PASS (40 of 100) in reporting the results of trials of any of the 5 involved rheumatic diseases with pain, patient global assessment, physical function, or physician global assessment used as outcome criteria.