Comparative Effectiveness of Tai Chi Versus Physical Therapy for Knee Osteoarthritis

Knee osteoarthritis is a major age-related public health problem and a leading cause of long-term pain and disability (1, 2). No effective medical treatments for the disease currently exist. Nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen are commonly used to treat osteoarthritis but often fail to relieve symptoms and may cause serious adverse effects (3). Physical therapy, a globally recommended element of the standard care regimen for knee osteoarthritis, produces moderate benefits for pain and physical functioning, but data on psychological well-being and durability effects are limited (4, 5). Identifying new and effective treatments for patients with knee osteoarthritis is an urgent clinical and public health priority. Tai Chi is a multicomponent traditional Chinese mindbody practice that combines meditation with slow, gentle, graceful movements; deep diaphragmatic breathing; and relaxation (6). Previous studies have indicated that Tai Chi can reduce pain and improve physical and psychological health among patients with chronic rheumatic disorders, such as rheumatoid arthritis and fibromyalgia (713). In our previous randomized trial, participants with knee osteoarthritis who completed 12 weeks of Tai Chi showed greater improvements in pain, physical function, depression, and health status compared with an attention control group (12). A 2013 updated meta-analysis of 7 studies that included 348 participants with osteoarthritis showed significant reductions in pain and improvements in physical function after 8 to 24 weeks of Tai Chi training compared with a waiting list, attention control, or usual physical activity (14). Those prior trials suggested that Tai Chi could provide a practical exercise regimen with an integrative mindbody approach to manage knee osteoarthritis. The physical component provides exercise benefits that are consistent with recommendations for knee osteoarthritis (physical function, balance, and muscle strength) (15), and the mind component promotes psychological well-being, life satisfaction, and improved perceptions of health (9, 16). To date, however, no randomized trials have directly compared Tai Chi and standard care treatments. The primary goal of this study was to compare the effectiveness of Tai Chi versus a physical therapy regimen among a large sample of patients with symptomatic and radiographic knee osteoarthritis who were seen in the clinical setting and followed for 12 months. Supplement. Study Protocol Methods Design Overview This 52-week, single-blind, randomized, comparative effectiveness trial recruited participants with symptomatic and radiographic knee osteoarthritis. Patients were randomly assigned to either Tai Chi (2 times per week for 12 weeks) or physical therapy in a clinical setting (2 times per week for 6 weeks, followed by 6 weeks of rigorously monitored home exercise). Details of the trial design and conduct have been published (17) and registered at ClinicalTrials.gov (NCT01258985). The study was approved by the Tufts Health Sciences Institutional Review Board and overseen by an independent data and safety monitoring board. Setting and Participants The trial was conducted at Tufts Medical Center in Boston, Massachusetts, between October 2010 and September 2014. Participants were recruited through multimodal strategies, including print advertisements, online media, a booth at a senior exposition, and a clinical patient database. We obtained informed consent before baseline assessments for eligibility. We enrolled persons aged 40 years or older who met American College of Rheumatology criteria for symptomatic knee osteoarthritis and had radiographic evidence of tibiofemoral or patellofemoral osteoarthritis (defined as the presence of a definite osteophyte in the tibiofemoral compartment and/or the patellofemoral compartment, as assessed on standing anteriorposterior and lateral or sunrise views) (18). All participants were required to have a score of 40 or greater on at least 1 of the 5 questions in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale (range of 0 to 100, with higher scores indicating greater pain) at baseline. A study rheumatologist (W.H.) confirmed eligibility of applicants. We excluded persons who had participated in Tai Chi or physical therapy in the past year; those with current serious medical conditions, such as dementia, symptomatic heart or vascular disease, or recent stroke, that would limit full participation; those with intra-articular steroid or intra-articular hyaluronic acid injections in the past 3 or 6 months or reconstructive surgery before baseline screening on the most severely affected knee; and those with a score less than 24 on the Mini-Mental State Examination (19). Participants who satisfied eligibility criteria were offered enrollment. Randomization Participants were randomly assigned in a 1:1 ratio to Tai Chi or physical therapy after the baseline evaluation. Randomization was done in 9 consecutive cycles, comprising about 20 participants each. Within each block of patients randomly assigned in each cycle, those assigned to Tai Chi were further randomly assigned to 1 of 3 instructors so that each instructor treated 1 group every 3 blocks. This design allowed for assessment of instructor-level effects. Pseudorandom numbers were generated in advance by the statistician (C.S.) using the R statistical package (20). Assignments were concealed in sealed, opaque envelopes with date and signature labels. The study coordinator opened the consecutive envelopes individually after obtaining consent and confirming eligibility. Research study nurses, physical function assessors, and sponsor personnel were blinded to the treatment assignments during enrollment. The blinded assessors did not have access to the data until data collection was complete. Interventions Tai Chi and physical therapy ran concurrently to minimize seasonal influences on disease activity. We encouraged participants to maintain routine activities but refrain from new exercises outside the study. Both groups received educational information about the importance of physical activity and home practice. We tracked reasons for missed sessions and asked participants to complete daily logs indicating duration of practice. Participants were encouraged to integrate at least 30 minutes of Tai Chi or physical therapy into their daily routine throughout follow-up. Attendance was monitored during each in-person session by using attendance forms and sign-in sheets. Study staff made monthly calls to monitor adherence throughout the 1-year follow-up. Tai Chi The 60-minute Tai Chi sessions occurred twice per week for 12 weeks. We recruited 3 experienced Tai Chi instructors from the greater Boston area. We developed a standardized classical Yang style Tai Chi protocol for knee osteoarthritis that was based on the literature (13). Before study initiation, the principal investigator (C.W.) and the Tai Chi master (R.R., who was also 1 of the 3 instructors) reviewed the concepts of knee osteoarthritis and trained the other instructors (17, 21). In the first session, participants received printed materials on Tai Chi principles, practice techniques, and safety precautions. The instructor explained mindbody exercise theory and procedures. Subsequent sessions started with a warm-up and a review of Tai Chi principles and movement, breathing techniques, and relaxation methods. Participants were instructed to practice Tai Chi at home for at least 20 minutes per day. The principal investigator monitored all sessions by regularly reviewing video recordings and providing feedback throughout the study. After completing the 12-week intervention (24 sessions), participants were instructed to continue Tai Chi practice for 52 weeks with the aid of provided homework materials. Physical Therapy The physical therapy protocol followed U.S. guidelines for knee osteoarthritis treatment (15) and consisted of two 30-minute outpatient sessions per week for 6 weeks. Before enrollment, the supervising physical therapist (M.I.) trained the 3 physical therapists. She observed evaluations and interventions during each treatment cycle to ensure consistency in documentation and provided feedback for program progression (17). Depending on the diagnostic findings in the initial musculoskeletal examination, the therapist targeted physical therapy regimens to address specific treatment goals developed collaboratively with the participant. At each session, the physical therapist examined the participant for adverse signs and symptoms before proceeding with manual therapy or exercise. Patients were encouraged to also perform exercises at home. After 6 weeks, participants were instructed to continue exercises in 30-minute sessions 4 times per week for 6 weeks. These were monitored weekly by telephone by using standardized forms to ascertain frequency, exercises completed, adverse events, and adherence. Outcomes and Follow-up Knee osteoarthritis outcomes, which were measured at baseline and 12, 24, and 52 weeks, were drawn from the core set recommended by the Osteoarthritis Research Society International (OARSI) and focused on pain, physical function, and patients' overall assessment of their disease severity (22). Primary Outcome The primary outcome was the change in WOMAC pain subscale score between baseline and 12 weeks. The WOMAC is a validated, self-administered visual analogue scale designed specifically to evaluate osteoarthritis symptoms (23). Secondary Outcomes Secondary outcomes were measured at baseline and 12, 24, and 52 weeks and included WOMAC physical function and stiffness scores, Patient Global Assessment score, Beck Depression Inventory-II score (24), scores on the physical and mental components of the 36-item Short Form Health Survey (SF-36) (25), Arthritis Self-Efficacy Scale score (26), and results of the 6-minute walk test (27) and the 20-mete