Analysis of outcome measures for persons with patellofemoral pain: which are reliable and valid?1☆,
Section snippets
Methods
The analyses for this study were performed using the results of a randomized, double-blind, placebo-controlled trial that evaluated the efficacy of conservative treatment for patellofemoral pain.5 In that trial, 71 participants (age range, 12–40y) were recruited from among health professionals, by advertisements, and through the media in Melbourne, Australia. For all participants, outcome assessment was performed by 1 of the 2 investigators (KMC, SMC), who were blinded to group allocation. For
Results
Of the 71 participants who enrolled in the trial, 67 (33 physiotherapy, 34 placebo) completed the final assessment and were included in the analyses of the validity and responsiveness of outcome measures. Subject characteristics are described in table 1. There were 23 women and 13 men in the physiotherapy group and 23 women and 12 men in the placebo group. There were no differences in the frequency of leg dominance or side of worst pain between the 2 groups. Visual analysis of baseline data
Discussion
This study evaluated the outcome measures used in a clinical trial of treatment for patellofemoral pain. The results indicate that the VAS-U and the AKPS were the most responsive outcome measures in this patient population. The minimal clinically relevant difference required to detect a treatment effect was calculated for each measure, thus enabling recommendations for future trials. The following is a discussion of the results of the empirical testing of the outcome measures (reliability,
Conclusions
There is no criterion standard outcome measure to assess outcomes of treatment for patellofemoral pain. Therefore, clinical trials have traditionally used a combination of outcome measures designed to address the pain, disability, and functional capacity of participants with patellofemoral pain. This study investigated the reliability, validity, and responsiveness of several outcome measures. The results of these tests indicate that the VAS for usual or worst pain and AKPS are the most valid
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Supported by the Physiotherapy Research Foundation and Health Professional Training fellowships from the National Health and Medical Research Council (Australia) (Regkey nos. 209168, 251762).
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No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated.