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


Author: Lee AC1, Harvey WF1, Price LL2, Han X1, Driban JB1, Iversen MD3, Desai SA4, Knopp HE4, Wang C5

Affiliation: <sup>1</sup>Center for Complementary and Integrative Medicine, Division of Rheumatology, Tufts Medical Center, Boston, MA, USA.

<sup>2</sup>Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, MA, USA; Tufts Clinical and Translational Science Institute, Tufts University, Boston, MA, USA.

<sup>3</sup>Department of Physical Therapy, Movement and Rehabilitation Sciences, Northeastern University, and Section of Clinical Sciences, Department of Medicine, Brigham & Women's Hospital, Harvard Medical School, Boston, MA,USA.

<sup>4</sup>Department of Physical Medicine and Rehabilitation, Tufts Medical Center, Boston, MA, USA.

<sup>5</sup>Center for Complementary and Integrative Medicine, Division of Rheumatology, Tufts Medical Center, Boston, MA, USA. Electronic address: cwang2@tuftsmedicalcenter.org.
Conference/Journal: PM R.
Date published: 2018 Jan 30
Other:
  Pages: S1934-1482(17)30178-8   ,  Special Notes: doi: 10.1016/j.pmrj.2018.01.003. [Epub ahead of print]   ,  Word Count: 310  
    BACKGROUND: Therapeutic exercise is a currently recommended non-pharmacological 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 two 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: 182 participants with symptomatic KOA (mean age 61 years; BMI 32kg/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 to 500) and function (0 to 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 4 to 5 attendance-weeks for ≥50% improvement. On multivariable models, outcome expectations were independently associated with incident function response (Hazard Ratio: 1.47; 95% CI: 1.004 to 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 optimize patient-centered exercise treatments and better manage patient expectations.



LEVEL OF EVIDENCE: Level I.



Copyright © 2018 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.



KEYWORDS: Dose Response; Exercise; Knee Osteoarthritis; Physical Therapy; Tai Chi



PMID: 29407226  DOI: 10.1016/j.pmrj.2018.01.003