Association between Pre-Intervention Physical Activity Level and Treatment Response to Exercise Therapy in Persons with Knee Osteoarthritis - An Exploratory Study.

OBJECTIVE: Examine whether pre-intervention physical activity (PA) level is associated with achieving a positive treatment response of pain and/or function improvement after a 12-week exercise intervention in participants with knee osteoarthritis (OA). METHODS: We performed a secondary analysis of a randomized, single-blind comparative effectiveness trial showing similar treatment effects between Tai Chi mind-body exercise and standard physical therapy intervention for knee OA. Baseline PA was assessed by Community Healthy Activities Model Program for Seniors (CHAMPS) Questionnaire and, in a subsample, by tri-axial accelerometers. OMERACT-OARSI dichotomous responder criteria was used for clinically meaningful improvement at follow-up. Associations between baseline self-reported PA by CHAMPS and outcomes of responders vs. non-responders (reference group) were assessed using logistic regressions, adjusting for demographic covariates. We compared objectively-measured PA by accelerometry between responders vs. non-responders using Wilcoxon tests. RESULTS: Our sample consisted of 166 participants with knee OA who completed both baseline and 12-week post-intervention evaluations: mean age 60.7 year (SD 10.5), BMI 32.4 kg/m2 (6.9), 119 (72%) women, and 138 (83%) OMERACT-OARSI responders. Neither time spent in total PA (OR 1.00; 95% CI 0.96, 1.03) nor time in moderate-to-vigorous (MV) PA (OR 1.01; 95% CI 0.93, 1.09) at pre-intervention were associated with being a responder. Similar findings were observed in 42 accelerometry sub-cohort participants. CONCLUSION: Pre-intervention PA level (subjective report or objective measurement) was not associated with whether an individual will achieve favorable treatment outcomes after a 12-week exercise intervention, suggesting that regardless of pre-intervention PA level, individuals will likely benefit from structured exercise interventions.

Dose-Response Effects of Tai Chi and Physical Therapy Exercise Interventions in Symptomatic Knee Osteoarthritis.

BACKGROUND: Therapeutic exercise is a currently recommended nonpharmacological treatment for knee osteoarthritis (KOA). The optimal treatment dose (frequency or duration) has not been determined. OBJECTIVE: To examine dose-response relationships, minimal effective dose, and baseline factors associated with the timing of response from 2 exercise interventions in KOA. DESIGN: Secondary analysis of a single-blind, randomized trial comparing 12-week Tai Chi and physical therapy exercise programs (Trial Registry #NCT01258985). SETTING: Urban tertiary care academic hospital PARTICIPANTS: A total of 182 participants with symptomatic KOA (mean age 61 years; BMI 32 kg/m2, 70% female; 55% white). METHODS: We defined dose as cumulative attendance-weeks of intervention, and treatment response as ≥20% and ≥50% improvement in pain and function. Using log-rank tests, we compared time-to-response between interventions, and used Cox regression to examine baseline factors associated with timing of response, including physical and psychosocial health, physical performance, outcome expectations, self-efficacy, and biomechanical factors. MAIN OUTCOME MEASURES: Weekly Western Ontario and McMasters Osteoarthritis Index (WOMAC) pain (0-500) and function (0-1700) scores. RESULTS: Both interventions had an approximately linear dose-response effect resulting in a 9- to 11-point reduction in WOMAC pain and a 32- to 41-point improvement in function per attendance-week. There was no significant difference in overall time-to-response for pain and function between treatment groups. Median time-to-response for ≥20% improvement in pain and function was 2 attendance-weeks and for ≥50% improvement was 4-5 attendance-weeks. On multivariable models, outcome expectations were independently associated with incident function response (hazard ratio = 1.47, 95% confidence interval 1.004-2.14). CONCLUSIONS: Both interventions have approximately linear dose-dependent effects on pain and function; their minimum effective doses range from 2-5 weeks; and patient perceived benefits of exercise influence the timing of response in KOA. These results may help clinicians to optimize patient-centered exercise treatments and better manage patient expectations. LEVEL OF EVIDENCE: II.

Could Activity Modifications Indicate Physical Decline Among Adults With Symptomatic Knee Osteoarthritis?

OBJECTIVES: Mobility activity modifications indicate early functional losses that act as precursors to future declines among community-dwelling older adults. However, there is scarce evidence on whether activity modifications indicate poorer physical health among adults with symptomatic osteoarthritis, a major cause of disability. Our purpose was to investigate whether patient-reported mobility activity modifications indicated poorer physical health among adults with symptomatic knee osteoarthritis. DESIGN: Secondary cross-sectional analysis of randomized trial data was performed. Preclinical Disability Questionnaire was used to group participants into the following three categories: difficulty, modified, and no difficulty walking/stair climbing. Kruskal Wallis and χ tests were used to compare clinical factors across groups. RESULTS: Among 121 participants (median age = 60 yrs; 73% female; 60% white), less than 10% had modified walking/stair climbing. Compared with those with no walking difficulty, participants with modified walking had significantly less balance (P = 0.01) and global health (P = 0.01) as well as greater knee pain (P = 0.05) and physical disability (P = 0.04). Those with modified stair climbing had significantly smaller walking distances (P = 0.03) compared with those with no difficulty stair climbing. CONCLUSIONS: Activity modifications may signal early impairments in physical health among people with symptomatic knee osteoarthritis. If confirmed, patient-reported activity modifications may enhance symptom evaluation in osteoarthritis and enable a better understanding of the disablement process.

Effects of Tai Chi versus Physical Therapy on Mindfulness in Knee Osteoarthritis.

Tai Chi mind-body exercise is widely believed to improve mindfulness through incorporating meditative states into physical movements. A growing number of studies indicate that Tai Chi may improve health in knee osteoarthritis (OA), a chronic pain disease and a primary cause of global disability. However, little is known about the contribution of mindfulness to treatment effect of Tai Chi practice. Therefore, our purpose was to investigate the effect of Tai Chi mind-body practice compared to physical therapy (PT) on mindfulness in knee OA. Adults with radiographic-confirmed, symptomatic knee OA were randomized to either 12 weeks (twice weekly) of Tai Chi or PT. Participants completed the Five Facet Mindfulness Questionnaire (FFMQ) before and after intervention along with commonly-used patient-reported outcomes for pain, physical function, and other health-related outcomes. Among 86 participants (74% female, 48% white, mean age 60 years, 85% at least college educated), mean total FFMQ was 142±17. Despite substantial improvements in pain, function, and other health-related outcomes, each treatment group's total FFMQ did not significantly change from baseline (Tai Chi= 0.76, 95% CI: -2.93, 4.45; PT= 1.80, 95% CI: -2.33, 5.93). The difference in total FFMQ between Tai Chi and PT was not significant (-1.04 points, 95% CI: -6.48, 4.39). Mindfulness did not change after Tai Chi or PT intervention in knee OA, which suggests that Tai Chi may not improve health in knee OA through cultivating mindfulness. Further study is needed to identify underlying mechanisms of effective mind-body interventions among people with knee OA.

Responsiveness and Minimally Important Differences for 4 Patient-Reported Outcomes Measurement Information System Short Forms: Physical Function, Pain Interference, Depression, and Anxiety in Knee Osteoarthritis.

Patient-Reported Outcomes Measurement Information System (PROMIS) instruments can provide valid, interpretable measures of health status among adults with osteoarthritis (OA). However, their ability to detect meaningful change over time is unknown. We evaluated the responsiveness and minimally important differences (MIDs) for 4 PROMIS Short Forms: Physical Function, Pain Interference, Depression, and Anxiety. We analyzed adults with symptomatic knee OA from our randomized trial comparing Tai Chi and physical therapy. Using baseline and 12-week scores, responsiveness was evaluated according to consensus standards by testing 6 a priori hypotheses of the correlations between PROMIS and legacy change scores. Responsiveness was considered high if ≥5 hypotheses were confirmed, and moderate if 3 or 4 were confirmed. MIDs were evaluated according to prospective change for people achieving previously-established MID on legacy comparators. The lowest and highest MIDs meeting a priori quality criteria formed a MID range for each PROMIS Short Form. Among 165 predominantly female (70%) and white (57%) participants, mean age was 61 years and body mass index was 33. PROMIS Physical Function had 5 confirmed hypotheses and Pain Interference, Depression, and Anxiety had 3 or 4. MID ranges were: Depression = 3.0 to 3.1; Anxiety = 2.3 to 3.4; Physical Function = 1.9 to 2.2; and Pain Interference = 2.35 to 2.4. PROMIS Physical Function has high responsiveness, and Depression, Anxiety, and Pain Interference have moderate responsiveness among adults with knee OA. We established the first MIDs for PROMIS in this population, and provided an important standard of reference to better apply or interpret PROMIS in future trials or clinical practice. PERSPECTIVE: This study examined whether PROMIS Short Form instruments (Physical Function, Pain Interference, Depression, and Anxiety) were able to detect change over time among adults with knee OA, and provided minimally important change estimates for each measure. This standard of reference can help apply or interpret these instruments in the future.

Mindfulness Is Associated With Treatment Response From Nonpharmacologic Exercise Interventions in Knee Osteoarthritis.

OBJECTIVE: To examine the association between baseline mindfulness and response from exercise interventions in knee osteoarthritis (OA). DESIGN: Cohort study; responder analysis of a clinical trial subset. SETTING: Urban tertiary care academic hospital. PARTICIPANTS: Participants with symptomatic, radiographic knee OA (N=86; mean age, 60y; 74% female; 48% white). INTERVENTIONS: Twelve weeks (twice per week) of Tai Chi or physical therapy exercise. MAIN OUTCOME MEASURES: Treatment response was defined using Osteoarthritis Research Society International criteria indicating meaningful improvements in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain, WOMAC function, or Patient Global Assessment scores. At baseline, participants completed the Five Facet Mindfulness Questionnaire (mean total score, 142±17) and were grouped into 3 categories of total mindfulness: higher, medium, or lower. Relative risk (RR) ratios were used to compare treatment response across groups. RESULTS: Participants with higher total mindfulness were 38% (95% confidence interval [CI], 1.05-1.83) more likely to meet responder criteria than those with lower mindfulness. We found no significant difference between medium and lower mindfulness groups (RR=1.0; 95% CI, 0.69-1.44). Among the 5 mindfulness facets, medium acting-with-awareness was 46% (95% CI, 1.09-1.96) more likely to respond than lower acting-with-awareness, and higher acting-with-awareness was 34% more likely to respond, but this did not reach significance (95% CI, 0.97-1.86). CONCLUSIONS: In this study, higher mindfulness, primarily driven by its acting-with-awareness facet, was significantly associated with a greater likelihood of response to nonpharmacologic exercise interventions in knee OA. This suggests that mindfulness-cultivating interventions may increase the likelihood of response from exercise.