Reliability, construct validity and responsiveness of the Osteoarthritis Research Society International (OARSI) core set of performace-based tests for subjects with knee Osteoarthritis

Abstract

Knee osteoarthritis (KOA) is commonly associated with functional impairments that can be measured subjectively and objectively. Subjective measures assess what patients perceive they can do, while objective measures assess what patients actually can do. Osteoarthritis Research Society International (OARSI) recommended a core set of three performance-based tests (30 seconds chair stand test, 40 meters fast-paced walk and stair-climb test) for subjects with KOA. Despite the OARSI recommendation, these performance-based tests had its reliability, construct validity and responsiveness tested only in patients at the final stage of the disease, which are patients eligible for total knee arthroplasty. Considering that this population is not the focus of conservative treatment, performance-based tests should be tested in individuals with mild and moderate KOA. In addition, minimal clinically important difference (MCID) has not been investigated. Objective: 1) to investigate the reliability, construct validity, and responsiveness of the performance-based tests recommended by OARSI for subjects with KOA; 2) to investigate the minimal detectable change (MDC), standard error of measurement (SEM), and MCID of the performance-based tests recommended by OARSI for subjects with KOA. Methods: A total of 115 individuals will be included with > 45 years old and diagnosed with KOA. Performance-based tests, pain intensity, physical function questionnaires and level of physical activity will be assessed for all participants. The first two measures will have 7 days between them and the third measure will be performed 6 months after the first measure. Intrarater analysis between measures will be performed for reliability (ICC2,1), while construct validity and responsiveness will be analyzed using Pearson or Spearman correlation test. Performance-based tests will be considered valid whether at least 75% of hypothesis are confirmed. In addition, SEM, MDC, and MCID will also be calculated. (AU)