Transcutaneous electrical nerve stimulation for advanced cancer pain inpatients in specialist palliative care-a blinded, randomized, sham-controlled pilot cross-over trial.

Purpose: Transcutaneous electrical nerve stimulation (TENS) is a treatment option for cancer pain, but the evidence is inconclusive. We aimed to evaluate the efficacy and safety of TENS.

Methods: A blinded, randomized, sham-controlled pilot cross-over trial (NCT02655289) was conducted on an inpatient specialist palliative care ward. We included adult inpatients with cancer pain ≥ 3 on an 11-point numerical rating scale (NRS). Intensity-modulated high TENS (IMT) was compared with placebo TENS (PBT). Patients used both modes according to their preferred application scheme during 24 h with a 24-h washout phase. The primary outcome was change in average pain intensity on the NRS during the preceding 24 h. Responders were patients with at least a "slight improvement."

Results: Of 632 patients screened, 25 were randomized (sequence IMT-PBT = 13 and PBT-IMT = 12). Finally, 11 patients in IMT-PBT and 9 in PBT-IMT completed the study (N = 20). The primary outcome did not differ between groups (IMT minus PBT: - 0.2, 95% confidence interval - 0.9 to 0.6). However, responder rates were higher in IMT (17/20 [85%] vs. 10/20 [50%], p = 0.0428). Two patients experienced an uncomfortable feeling caused by the current, one after IMT and one after PBT. Seven patients (35%) desired a TENS prescription. Women and patients with incident pain were most likely to benefit from TENS.

Conclusion: TENS was safe, but IMT was unlikely to offer more analgesic effects than PBT. Even though many patients desired a TENS prescription, 50% still reported at least "slight pain relief" from PBT. Differences for gender and incident pain aspects demand future trials.