A Comparison of 3 Methodological Approaches to Defining Major Clinically Important Improvement of 4 Performance Measures in Patients With Hip Osteoarthritis

STUDY DESIGN: Prospective cohort study. OBJECTIVES: To establish the major clinically important improvement (MCII) of the timed up-and-go test (TUG), 40-meter self-paced walk test (40-m SPWT), 30-second chair stand (30 CST), and a 20-cm step test in patients with hip osteoarthritis (OA) undergoing physiotherapy treatment. As a secondary aim, a comparison of methods was employed to evaluate the effect of method on the reported MCII. BACKGROUND: Minimal clinically important difference scores are commonly used by rehabilitation professionals to determine patient response following treatment. A gold standard for calculating MCII has yet to be determined, which has resulted in problems of interpretation due to varied results. METHODS: As part of a randomized controlled trial, 65 patients were randomized into a physiotherapy treatment group for hip OA, in which they completed 4 physical performance measures at baseline and 9 weeks. Upon completion of physiotherapy, patients assessed their response to treatment on a 15-point global rating of change scale (GRCS). MCII was estimated using 3 variations of an anchor-based method, based on the patient's opinion. RESULTS: A comparison of 3 methods resulted in the following change scores being best associated with our definition of MCII: a reduction equal to or greater than 0.8, 1.4, and 1.2 seconds for the TUG; an increase equal to or greater than 0.2, 0.3, and 0.2 m/s for the 40-m SPWT; an increase equal to or greater than 2.0, 2.6, and 2.1 repetitions for the 30 CST; an increase equal to or greater than 5.0, 12.8, and 16.4 steps for the 20-cm step test. CONCLUSION: The variation in methods provided very different results. This illustrates the importance of comparing methodologies and reporting a range of values associated with the MCII, as such values vary, depending upon the methodology chosen. J Orthop Sports Phys Ther 2011;41(5):319-327 Epub 18 February 2011. doi:10.2519/jospt.2011.3515