A Cochrane review [Abstract] 1 included 20 studies with a total of 585 subjects. High-frequency TENS reduced pain compared with placebo or no treatment (mean difference (MD) −1.39, 95% CI −2.51 to −0.28; 10 RCTs, n=345; low‐certainty evidence; I²=88%). Low-frequency TENS may reduce pain compared with placebo or no treatment (MD −2.04, 95% CI −2.95 to −1.14; 3 RCTs, n=645; low‐certainty evidence; I²=0%).
A systematic review 2 assessed TENS and heat therapy for pain relief. 6 studies on TENS and 3 studies on heat therapy were included. On the PEDRO quality scale, the trials methodological quality was 4.8 out of 10 for TENS and 6.3 out of 10 for heat therapy. TENS and heat therapy both showed evidence of pain reduction, but no study included quality of life as an outcome. Meta-analysis was not possible due to substantial heterogeneity in included studies.
A study 3 randomly assigned 134 participants into the intervention group (TENS) and the sham group (sham TENS). The primary outcome was measured by the Numeric Rating Scale (NRS). A total of 122 participants completed the study. Compared to sham TENS, TENS showed a greater effect in pain relief with regard to the NRS (P < .01), duration of relief from dysmenorrheal pain (P < .01), and number of ibuprofen tablets taken (P < .01). However, no significant differences in the quality of life, measured by the WHOQOL-BREF score, were found.
Comment: The quality of evidence is downgraded by limitations in study quality (unclear allocation concealment and blinding).
Primary/Secondary Keywords