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Is the association between physical activity and fatigue mediated by physical function or depressive symptoms in symptomatic knee osteoarthritis? The Multicenter Osteoarthritis Study
Journal article   Peer reviewed

Is the association between physical activity and fatigue mediated by physical function or depressive symptoms in symptomatic knee osteoarthritis? The Multicenter Osteoarthritis Study

H O Fawole, D T Felson, L A Frey-Law, S R Jafarzadeh, A Dell'Isola, M P Steultjens, M C Nevitt, C E Lewis, J L Riskowski and SFM Chastin
Scandinavian journal of rheumatology, Vol.50(5), pp.372-380
09/03/2021
DOI: 10.1080/03009742.2020.1854850
PMCID: PMC8448897
PMID: 33749506
url
https://researchonline.gcu.ac.uk/en/publications/c4964a87-22bc-4292-9db7-27e3b17a1f0cView
Open Access

Abstract

Objectives: To examine whether physical activity (PA) was associated with fatigue, and quantify the extent of potential mediation through depressive symptoms or physical function (PF) on the relationship between PA and fatigue in symptomatic knee osteoarthritis (KOA). Method: This longitudinal study used data from the Multicenter Osteoarthritis Study (n = 484), comprising subjects aged ≥ 50 years. Baseline PA was quantified via an ankle-worn accelerometer. The outcome was fatigue, measured using a 0-10 rating scale at 2 year follow-up. Mediators included gait speed as a measure of PF and depressive symptoms at 2 year follow-up. Mediation analysis was carried out after adjustment for baseline confounders. Stratified analysis by baseline fatigue status [no/low (< 4) and high (≥ 4) fatigue] was performed. Results: A significant direct association was found between PA and fatigue at 2 years [unstandardized coefficient (B) = −0.054; 95% confidence interval (CI) −0.107, −0.002, p = 0.041]. The PA-fatigue relationship was not mediated by gait speed (B = −0.006; 95% CI −0.018, 0.001) or depressive symptoms (B = 0.009; 95% CI 0.009, 0.028). In the subgroup with high baseline fatigue, direct associations were found between PA and fatigue (gait speed model:, B = −0.107; 95% CI −0.212, −0.002, p = 0.046; depressive symptoms model: B = −0.110; 95% CI −0.120, −0.020, p = 0.017); but in the no/low baseline fatigue group, no significant association was found between PA and fatigue. Conclusion: In the symptomatic KOA population, higher baseline PA was directly associated with reduced fatigue 2 years later, especially in those with high baseline fatigue. However, this relationship was not mediated by depressive symptoms or PF.

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