Predictive value of performance-based physical function measures for osteoarthritis-related health outcomes and response to a physical activity intervention
Date
2019
Authors
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Publisher
University of Delaware
Abstract
Background: Over 14 million Americans have symptomatic knee osteoarthritis (OA), which has no cure. Knee OA is a leading cause of functional limitation such as difficulty walking and getting up from a chair, which can be addressed by rehabilitation. However, less than 14% of people with knee OA receive rehabilitation. One reason for low referrals may be the inability to identify those that are in need. Performance-based measures of physical function that identify functional limitation are a potential means to select such individuals. However, clinical assessment of performance-based measures is not part of the routine practice for knee OA. The purpose of this dissertation was to investigate the predictive value of selected clinically feasible performance-based measures with future health outcomes in order to better identify who may be possible candidates for rehabilitation. ☐ Objective: The long-term goal of this work is to identify individuals with knee OA who may benefit from rehabilitation. The overall objective of this dissertation was to investigate if performance-based physical function measures predict OA-related health outcomes (Aims 1 to 3) in adults with knee OA and response to physical therapist led physical activity intervention in adults after total knee replacement (TKR) (Exploratory aim). ☐ Methods: A publicly available large knee OA-related dataset, the Osteoarthritis Initiative (OAI) was used to answer research questions in Aims 1 to 3. The primary study exposures were physical function measures i.e., 1) walking speed measured using a 20-m walk test and 2) repeated chair stands measured using a five times sit-to-stand test. The main study outcomes were 1) physical activity measured using accelerometers, 2) time to all-cause mortality, and 3) time to total knee replacement. For the exploratory aim, we used data from the on-going randomized clinical trial, where individuals post TKR who underwent physical therapy were recruited. ☐ Results: Thresholds of physical function measures indicative of physical inability to walk at least 6000 steps/day were identified in Aim 1. These thresholds may indicate when people with knee OA need rehabilitation to address underlying functional limitation such as impaired endurance, to minimize the risk of future poor health and increase the ability to be physically active. The thresholds on the physical function measures may serve as a clinical target for health professionals. We found that physical function measures assessed at one time-point may be sufficient to gauge mortality risk rather than being measured repeatedly over time. The key finding from Aim 3 was that walking speed was a robust predictor for all-cause mortality in older as well as middle-aged adults with knee OA. Thus, walking speed may be a simple indicator of health in adults with knee OA. Health care professionals may use walking speed to assess expected health and tailor goals of care for knee OA population. Finally, findings from exploratory aim suggests there may be subgroups of patients post-TKR who experience greater benefit from physical therapist led physical activity intervention. ☐ Conclusion: This dissertation provided preliminary evidence on the predictive value of physical function measures for OA-related health outcomes and response to a physical therapist led physical activity intervention. This evidence of the predictive value will provide healthcare professionals with meaningful clinical thresholds on the performance-based measures to assess functional limitation in adults with knee OA. These thresholds will not only aid in clinical decision making by telling clinicians, which patients may need rehabilitation to address functional limitation but also identify candidates who are ready for a physical activity intervention vs. those who may need other interventions such as rehabilitation first to address functional limitation and/or weight management.