The relation of stair climbing behaviors with developing poor health outcomes in knee osteoarthritis
Date
2023
Authors
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Publisher
University of Delaware
Abstract
Knee osteoarthritis (OA) impacts over 250 million adults worldwide and is a leading cause of functional limitation in older adults, such as slow walking or difficulty getting up from a chair. Difficulty with climbing stairs is often one the first-reported activity limitations in adults with knee OA, and because stair climbing is a high-demand functional task that taxes multiple body systems, reduced stair climbing ability may reflect early deficits in said body systems. Thus, changes to stair climbing behaviors may serve as a precursor to later decline in important health outcomes for adults with knee OA, namely functional limitation, knee replacement, and all-cause mortality – each of which impact those with knee OA at higher rates than the general population. ☐ Stair climbing behaviors, such as level of difficulty with climbing the stairs and frequency at which one climbs stairs, are simple measures to collect and typically intuitive for patients to recall when asked. Given this, and the level to which stair climbing taxes the body, stair climbing behaviors may serve as a functional vital sign that represents whole-body impairments, in a similar manner to walking speed. However, changes to stair climbing ability may occur at a much earlier stage than changes to walking speed or other less-demanding functional tasks, because of the greater physiological challenge it poses. And so early knowledge of changes to stair climbing behaviors may be a powerful clinical tool to predict future health status. ☐ To determine if stair climbing behaviors are related to functional limitation, knee replacement, and all-cause mortality, we used data from the Osteoarthritis Initiative (OAI), a large, prospective cohort study of adults with or at high risk of knee OA. Using survival analysis, we assessed the hazard of each of the three health outcomes across our stair climbing exposures. ☐ In Aim 1, we found that adults with knee OA who have any amount of difficulty with climbing stairs were at a greater hazard for developing functional limitation as measured by walking speed, repeated chair stand time, and WOMAC Physical Function score. This ranged from 37-161% greater hazard across the three outcomes. We also found that stair climbing frequency, as measured both by flights/week and days/week, was associated with the three functional outcomes, however there was no clear trend within the exposure groups. These results ranged from 6-34% lower hazard across all outcomes. ☐ In Aim 2, we further found that stair climbing difficulty was related to greater hazard of knee replacement. Those who were limited a lot in their stair climbing had a 61% greater hazard of knee replacement, turning to knee replacement surgery on average 1.5 years before those with no difficulty (3.8 years vs 5.3 years, respectively). We also found that greater stair climbing frequency was not associated with lower hazard for knee replacement. ☐ In Aim 3, we found that both greater stair climbing difficulty and climbing the stairs less frequently were associated with all-cause mortality. Adults with knee OA who were limited in any amount with their stair climbing had 54-84% greater hazard of all-cause mortality, and those who climbed at least 7 flights of stairs per week had 38% lower hazard of all-cause mortality. ☐ In sum, these findings strongly establish stair climbing difficulty as a yellow flag for future poor health outcomes in adults with knee OA and can be viewed as an additional functional vital sign for clinicians to use in evaluating their patients. Further, stair climbing frequency may have some utility in aiding this evaluation, as there was a weak relationship found with functional limitation and all-cause mortality. Stair climbing behaviors are simple to collect, intuitive to recall, and can be a powerful tool to add to the clinician’s toolbox when treating adults with knee OA.
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Keywords
All-cause mortality, Functional limitation, Knee osteoarthritis, Knee replacement, Stair climbing, Survival analysis, Osteoarthritis initiative