Arthritis & Rheumatism, Volume 60,
October 2009 Abstract Supplement
The 2009 ACR/ARHP Annual Scientific Meeting
Philadelphia October 16-21, 2009.
Associates of Tolerance to Neuromuscular Electrical Stimulation in Rheumatoid Arthritis
Piva1, Sara R., Strudle1, Nathan, Almeida1, Gustavo J. M., Wasko2, M. C., Fitzgerald1, G. Kelley, Delitto1, Anthony
Nearly two-thirds of patients with rheumatoid arthritis (RA) experience muscle weakness and atrophy. Neuromuscular electrical stimulation (NMES) is a viable intervention to treat muscle atrophy and weakness in RA. The therapeutic effect of NMES is dependent on the dose of electrical stimulation. Tolerance is a limiting factor of NMES effectiveness because patients must tolerate high doses of NMES to maximize gains in muscle function. Identifying factors associated with NMES tolerance may guide strategies to improve tolerance to this intervention. This study aimed to identify psychological factors associated with NMES tolerance in subjects with RA.
Thirty eight subjects with RA participated in this cross-sectional study, with age 60 ± 11 years, 63% female, BMI 27 ± 6. Measures of social and biomedical characteristics included age, gender, race, marital status, education, height, weight, disease duration, medication, and disability (HAQ). Psychological factors included pain coping strategies, pain acceptance, sense of control over life and environment, anxiety, depression, and the sensory and affective domains of pain. NMES procedure: Subjects sat on an isokinetic dynamometer. The maximum voluntary isometric contraction (MVIC) of the quadriceps femoris muscles strength was determined. Torque output during the MVIC was the reference to determine NMES dose (% of MVIC torque generated during electrically elicited muscle contraction). Then, 15 NMES contractions were administered to the quadriceps muscles (stimulus parameters 75Hz, 450 msec, on/off time 14/46sec). Intensity of the NMES was increased as tolerated. NMES tolerance was defined as the highest NMES dose tolerated by each subject during the NMES procedure. NMES procedure was repeated during 2 visits to allow adaptation to the electrical stimulation. Analysis: We calculated bivariate correlations between NMES tolerance and all other variables. Variables significantly correlated were selected to build a linear regression model to predict NMES tolerance. The social and biomedical characteristics were first forced into the model. Then, psychological factors were added using a stepwise approach.
Bivariate correlations demonstrated that more years of education, less disability, lower anxiety, and higher scores in 2 coping strategies (coping self-statements and ignoring pain sensation) were associated with higher NMES tolerance. After controlling for education and disability, only ignoring pain sensation was a predictor. Education and disability explained 45% of variability in NMES tolerance and ignoring pain sensation explained additional 13%. Regression diagnostics revealed that the assumptions of linear regression models were not violated.
RA subjects who ignore pain sensation tolerate higher doses of NMES. These results suggest that incorporating coping strategy techniques to help subjects ignore the sensation of pain will help to increase tolerance to the NMES.
To cite this abstract, please use the following information:
Piva, Sara R., Strudle, Nathan, Almeida, Gustavo J. M., Wasko, M. C., Fitzgerald, G. Kelley, Delitto, Anthony; Associates of Tolerance to Neuromuscular Electrical Stimulation in Rheumatoid Arthritis [abstract]. Arthritis Rheum 2009;60 Suppl 10 :1134