RANDOMIZATION IS IMPORTANT IN STUDIES WITH PAIN OUTCOMES - SYSTEMATICREVIEW OF TRANSCUTANEOUS ELECTRICAL NERVE-STIMULATION IN ACUTE POSTOPERATIVE PAIN

We set out to examine the evidence for the importance of randomization of transcutaneous electrical nerve stimulation (TENS) in acute post-o perative pain. Controlled studies were sought; randomization and analg esic and adverse effect outcomes were summarized. Forty-six reports we re identified by searching strategies. Seventeen reports with 786 pati ents could be regarded unequivocally as randomized controlled trials ( RCT) in acute postoperative pain. No meta-analysis was possible. In 15 of 17 RCT, we judged there to be no benefit of TENS compared with pla cebo. Of the 29 excluded trials, 19 had pain outcomes but were not RCT ; in 17 of these 19 TENS studies, the authors concluded that TENS had a positive analgesic effect. No adverse effects were reported. Non-ran domized studies overestimated treatment effects.