Minimal clinically important difference. Low back pain: Outcome measures

A proposed standard "core set" of outcome measures for low back pain includ es 5 domains: back-specific function, generic health status, pain, work dis ability, and patient satisfaction. This paper focuses on the 2 recommended back-specific measures of function: the Roland-Morris Disability Questionna ire (RDQ) and the Oswestry Disability Index (ODI). We specifically address their ability to measure change. A systematic review of the literature iden tified a total of 78 and 71 (RDQ and ODI. respectively) articles as potenti ally relevant. Detailed tables are provided for each citation, with the typ e of back pain population studied. the type of change measured, the estimat e of change, and the interval over which the change was studied. These tabl es should be used as a reference for sample size calculation. The responsiv eness of the RDQ found in the literature ranges from 2 to 8 points on its 0 to 24 scale depending on what change is being measured. As a rough guide, Poland recommends that a change in 2-3 points on the RDQ should be consider ed the minimum clinically important change. Choosing any value larger than 5 in designing a clinical trial would risk underpowering the trial, since f ewer patients are needed if a trial is designed on the basis of a large cha nge score.