Background/Purpose: Mindfulness is the ability to maintain a heightened awareness of one’s moment-to-moment experiences without judging or reacting. Recent evidence suggests that mindfulness may improve outcomes in chronic pain, but no study has examined whether mindfulness is a predictor of treatment response in OA. Our objective was to evaluate whether OA participants with higher baseline mindfulness are more likely to achieve OMERACT-OARSI treatment response after exercise intervention.

Methods: We performed a longitudinal analysis of pooled participants from a randomized trial comparing Tai Chi mind-body exercise to standard physical therapy regimen with similar treatment effect among adults with symptomatic knee OA (ACR criteria). A participant subset completed the WOMAC, Patient Global Assessment, and Five Facet Mindfulness Questionnaire (FFMQ) before and after 12-week intervention. Those among this subset were stratified into tertiles based on their total mindfulness score.  Treatment response was defined based on OMERACT-OARSI criteria: 1) ≥ 50% improvement in pain or function and change of ≥ 20 points on a scale of 0 to 100 in WOMAC pain or function, or 2) ≥ 2 of the following criteria: improvement of ≥20% and change > 10 points in WOMAC pain, improvement of ≥ 20% and change > 10 points in WOMAC function, or improvement of ≥20% in Patient Global and change > 10 points. We calculated risk ratios for each paired tertile comparison, and analysis of variance or chi-square tests to check for characteristic differences among the tertiles at baseline.

Results: We measured 76 of 86 baseline participants (mean age 60 years, 74% female, 48% white, 87% KL Grade ≥2, and 85% college-educated), for their follow-up visit. Table 1 summarizes the baseline characteristics of participants by tertile. The only difference in baseline characteristics was that higher mindfulness had higher BMI (p = 0.01). Table 2 summarizes the distribution of treatment response. Those with higher mindfulness were 1.4-fold more likely to meet responder criteria than those with either medium (95% CI: 1.1, 1.8; p = 0.01) or lower mindfulness (95% CI: 1.1, 1.8; p = 0.01).  No difference was found between medium and lower mindfulness (1.0; 95% CI: 0.7, 1.4; p = 0.98).

Conclusion: Knee OA participants with higher mindfulness are 40% more likely to respond to exercise intervention. Higher mindfulness may be a novel predictor of non-pharmacological treatment response among people with symptomatic knee OA. This finding may help optimize the design of exercise interventional trials in OA.                        

Table 1. Demographic and Clinical Characteristics of Participants by Mindfulness Levels
Variable			Lower Mindfulness	Medium  Mindfulness	Higher  Mindfulness	p-value
Age, years			63.1 (10.5)	57.4 (9.5)	60.5 (10.8)	0.11
BMI			29.9 (6.3)	33.0 (6.3)	35.3 (7.4)	0.01
Sex, N	Female		19	20	25	0.18
	Male		10	8	4
Pain duration, years; Mean (SD)			11.2 (16.0)	8.2 (8.4)	11.5 (15.1)	0.61
Kellgren Lawrence Grade, N		0	0	1	1	0.35
		1	2	4	0
		2	10	9	12
		3	14	11	9
		4	2	3	6
Race, N		White	11	14	16	0.37
		Black	11	8	11
		Other	7	6	2
Education, N		High school	7	3	3	0.33
		College	9	11	12
		College Grad	5	9	4
		Graduate School	8	5	10
Intervention, N		Tai Chi	17	13	16	0.64
		Physical Therapy	12	15	13
Total Mindfulness [min: max:] FFMQ Score Range, 39-195			124 (8.4) [98; 134]	141 (3.6) [135; 148]	161 (9.5) [149; 181]
WOMAC Pain* Score Range, 0-500mm			289.0 (111)	253.7 (93.1)	253.8 (95.7)	0.31
WOMAC Function* Score Range, 0-1700mm			946.4 (387.2)	930.8 (335.1)	921.1 (360.6)	0.96
Patient Global Assessment* Score Range, 0-10cm			5.2 (2.2)	5.1 (2.0)	5.2 (2.2)	0.98
All values are mean (SD), unless otherwise stated. FFMQ = Five Facet Mindfulness Questionnaire, higher scores = higher mindfulness; SD= Standard Deviation. *Higher scores = more pain, worse function, or more global disease.

 

Table 2. Distribution of Treatment Response by Mindfulness Levels*
Mindfulness Tertile	No Treatment Response	Treatment Response†	Row Total
Lower, N (%) [Score Min: 98; Max: 134]	7 (30.4%)	16 (69.6%)	23
Medium, N (%) [Score Min: 135; Max: 148]	8 (30.8%)	18 (69.2%)	26
Higher, N (%) [Score Min: 149; Max: 181]	1 (3.7%)	26 (96.3%)	27
Column Total	16	60	76
*Mindfulness measured as total Five Facet Mindfulness Questionnaire score; Score Range, 39-195. †Treatment response as defined by the OMERACT-OARSI Responder Criteria for OA.