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Transcutaneous electrical nerve stimulation (TENS) for the treatment of rheumatoid arthritis in the hand.

BACKGROUND
Rheumatoid arthritis (RA) is a chronic, inflammatory, system disease. It commonly affects the small peripheral joints (such as fingers and wrist). The main goals of intervention for RA are preventing joint deformity, preserving joint function, and reducing inflammation and pain. Transelectrical nerve stimulation (TENS) is a form of electrotherapy and is thought to produce analgesia according to the gate control theory.


OBJECTIVES
To determine the efficacy and safety of TENS in the treatment of RA of the hand. The primary outcomes of interest were relief of grip pain and resting pain intensity, relief of joint tenderness, number of tender joints and patient assessment of disease. The secondary objective was to determine the most effective mode of TENS application in pain control.


SEARCH STRATEGY
We searched for relevant studies, in English, in the Cochrane field of physical and related therapies, the Cochrane Controlled Trials Register, MEDLINE, EMBASE, HEALTHSTAR, Sports Discus, CINAHL, Current Contents, and the PEDro database, up to October 2002.


SELECTION CRITERIA
Two independent reviewers selected the trials that met predetermined inclusion criteria.


DATA COLLECTION AND ANALYSIS
Study results were extracted by two independent reviewers. Continuous outcomes were analyzed by weighted mean difference (WMD) using a fixed effects model.


MAIN RESULTS
Three RCTs, involving 78 people, were included in this review. AL-TENS and C-TENS were compared to placebo and to each other. Administration of 15 minutes of AL-TENS a week, for 3 weeks, resulted in a significant decrease in rest pain (67% relative benefit, 45 points absolute benefit on 100 mm VAS scale) but not in grip pain compared to placebo. AL-TENS did result in a clinical beneficial improvement in muscle power scores with a relative difference of 55%, and an absolute benefit of 0.98, compared to placebo. No significant difference was found between one 20-minute treatment duration of C-TENS versus AL-TENS, or C-TENS versus placebo on decrease in mean scores for rest pain or grip pain, or on the number of tender joints. Results showed a statistically significant reduction in joint tenderness, but no clinical benefit from C-TENS over placebo in relief of joint tenderness. No statistically significant difference was shown between 15 days of treatment with C-TENS or AL-TENS in relief of joint pain, although there was a clinically important benefit of C-TENS over AL-TENS on patient assessment of change in disease (risk difference 21%, NNT 5).


REVIEWER'S CONCLUSIONS
There are conflicting effects of TENS on pain outcomes in patients with RA. AL-TENS is beneficial for reducing pain intensity and improving muscle power scores over placebo while, conversely, C-TENS resulted in no clinical benefit on pain intensity compared with placebo. However C-TENS resulted in a clinical benefit on patient assessment of change in disease over AL-TENS. More well designed studies with a standardized protocol and adequate number of subjects are needed to fully conclude the effect of C-TENS and AL-TENS in the treatment of RA of the hand.