Predicting outcome of TENS in chronic pain: A prospective, randomized, placebo controlled trial

Abstract

Fifty-eight percent of the patients in the TENS group and 42.7% of the sham-TENS group were satisfied with treatment result (chi square=3.8, p=0.05). No differences were found for pain intensity. Patients diagnosed with osteoarthritis and related disorders (especially of the vertebral column) or peripheral neuropathic pain were less satisfied with high frequency TENS (OR=0.12 (95% CI 0.04-0.43) and 0.06 (95% CI 0.006-0.67), respectively). Injury of bone and soft tissue (especially postsurgical pain disorder) provided the best results. Treatment modality or interactions with treatment modality did not predict intensity of pain as a result of treatment. We conclude, that predicting the effect of high frequency TENS in chronic pain depends on the choice of outcome measure. Predicting patients' satisfaction with treatment result is related to the origin of pain. Predicting pain intensity reflects mechanisms of pain behavior and perceived control of pain, independent of treatment modality. Pain catastrophizing did not predict TENS treatment outcome.