Examining sex differences in knee pain: the Multicenter Osteoarthritis Study

SummaryObjectiveTo determine whether women experience greater knee pain severity than men at equivalent levels of radiographic knee osteoarthritis (OA).Design and methodsA cross-sectional analysis of 2712 individuals (60% women) without knee replacement or a recent steroid injection. Sex differences in pain severity at each Kellgren–Lawrence (KL) grade were assessed by knee using visual analog scale (VAS) scale and Western Ontario and McMaster Universities Arthritis Index (WOMAC) with and without adjustment for age, analgesic use, Body mass index (BMI), clinic site, comorbid conditions, depression score, education, race, and widespread pain (WSP) using generalized estimating equations. Effect sizes (Cohen's d) were also calculated. Analyses were repeated in those with and without patellofemoral OA (PFOA).ResultsWomen reported higher VAS pain at all KL grades in unadjusted analyses (d = 0.21–0.31, P < 0.0001–0.0038) and in analyses adjusted for all covariates except WSP (d = 0.16–0.22, P < 0.0001–0.0472). Pain severity differences further decreased with adjustment for WSP (d = 0.10–0.18) and were significant for KL grade ≤2 (P = 0.0015) and 2 (P = 0.0200). Presence compared with absence of WSP was associated with significantly greater knee pain at all KL grades (d = 0.32–0.52, P < 0.0001–0.0008). In knees with PFOA, VAS pain severity sex differences were greater at each KL grade (d = 0.45–0.62, P = 0.0006–0.0030) and remained significant for all KL grades in adjusted analyses (d = 0.31–0.57, P = 0.0013–0.0361). Results using WOMAC were similar.ConclusionsWomen reported greater knee pain than men regardless of KL grade, though effect sizes were generally small. These differences increased in the presence of PFOA. The strong contribution of WSP to sex differences in knee pain suggests that central sensitivity plays a role in these differences

The association between walking speed from short- and standard-distance tests with the risk of all-cause mortality among adults with radiographic knee osteoarthritis: data from three large United States cohort studies

Objective: Adults with radiographic knee OA (rKOA) are at increased risk of mortality and walking difficulty may modify this relation. Little is known about specific aspects of walking difficulty that increase mortality risk. We investigated the association of walking speed (objective measure of walking difficulty) with mortality and examined the threshold that best discriminated this risk in adults with rKOA. Methods: Participants with rKOA from the Johnston County Osteoarthritis Project (JoCoOA, longitudinal population-based cohort), Osteoarthritis Initiative and Multicenter Osteoarthritis Study (OAI and MOST, cohorts of individuals with or at high risk of knee OA) were included. Baseline speed was measured via 2.4-meter (m) walk test (short-distance) in JoCoOA and 20-m walk test (standard-distance) in OAI and MOST. To examine the association of walking speed with mortality risk over 9 years, hazard ratios (HR) and 95% confidence intervals (CI) were calculated from Cox regression models adjusted for potential confounders. A Maximal Likelihood Ratio Chi-square Approach was utilized to identify an optimal threshold of walking speed predictive of mortality. Results: Deaths after 9 years of follow-up occurred in 23.3% (290/1244) of JoCoOA and 5.9% (249/4215) of OAI + MOST. Walking 0.2 m/s slower during short- and standard-distance walk tests was associated with 23% (aHR [95%CI]; 1.23 [1.10, 1.39]) and 25% (1.25 [1.09, 1.43]) higher mortality risk, respectively. Walking <0.5 m/s on short-distance and <1.2 m/s standard-distance walk tests, best discriminated those with and without mortality risk. Conclusion: Slower walking speed measured via short- and standard-distance walk tests was associated with increased mortality risk in adults with rKOA

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

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