Reliability, validity, and responsiveness of functional tests in patients with total joint replacement

Abstract

Background and purpose: High-quality measurements are needed to develop meaningful clinical practice databases to assess the effectiveness of physical therapy. This study determined the reliability, validity, and responsiveness of measurements obtained with five functional tests graded with the newly developed Iowa Level of Assistance Scale.

Subjects and methods: Eighty-six patients with total hip or knee replacements were tested at various time periods during their hospitalization. Patients were tested for five functional activities by four therapists to establish the reliability and test responsiveness. The Harris Hip Rating Scale was administered to assess the validity of the functional score.

Results: The weighted Kappa statistic supported good intratester (K = .79-.90) and moderate intertester (K = .48-.78) reliability. The correlation between the Harris Hip Rating Scale scores and the total functional scores was high (r = -.86). The total functional score was responsive to 4 days of therapy postoperatively.

Conclusion and discussion: The assessment of function using the Iowa Level of Assistance Scale was shown to be highly reliable, valid, and responsive in patients following total hip or knee replacements.