Responsiveness of the activities of daily living scale of the knee outcome survey and numeric pain rating scale in patients with patellofemoral pain

Abstract

Objective: To assess internal and external responsiveness of the Activity of Daily Living Scale of the Knee Outcome Survey and Numeric Pain Rating Scale on patients with patellofemoral pain.

Design: One group pre-post design.

Subjects: A total of 60 individuals with patellofemoral pain (33 women; mean age 29.9 (standard deviation 9.6) years).

Methods: The Activity of Daily Living Scale and the Numeric Pain Rating Scale were assessed before and after 8 weeks of physical therapy program. Patients completed a global rating of change scale at the end of therapy. The standardized effect size, Guyatt responsiveness index, and the minimum clinical important difference were calculated.

Results: Standardized effect size of the Activity of Daily Living Scale was 0.63, Guyatt responsiveness index was 1.4, area under the curve was 0.83 (95% confidence interval: 0.72, 0.94), and the minimum clinical important difference corresponded to an increase of 7.1 percentile points. Standardized effect size of the Numeric Pain Rating Scale was 0.72, Guyatt responsiveness index was 2.2, area under the curve was 0.80 (95% confidence interval: 0.70, 0.92), and the minimum clinical important difference corresponded to a decrease of 1.16 points.

Conclusion: Information from this study may be helpful to therapists when evaluating the effectiveness of rehabilitation intervention on physical function and pain, and to power future clinical trials on patients with patellofemoral pain.

Figures

Fig. 1

Distribution of frequencies in the Activities of Daily Living Scale (ADLS), Numeric Pain Rating Scale (NPRS), and Global Rating of Change.

Fig. 2

Receiver operating characteristic curves for the changes in Activities of Daily Living Scale (ADLS) and Numeric Pain Rating Scale (NPRS). The circled values are the point nearest the uppermost left-hand corner of the graph for each measure. These points represent the minimum clinical important difference for the ADLS (7.14 percentage points) and NPRS (1.16 points).