Transcutaneous electrical nerve stimulation for women with primary dysmenorrhea: Study protocol for a randomized controlled clinical trial with economic evaluation

Primary dysmenorrhea (PD) is a common gynecological disorder characterized by cramping pain in the lower abdomen during menstruation, in the absence of identifiable pathology. While Transcutaneous Electrical Nerve Stimulation (TENS) is used to promote PD pain relief, there is still a need to understand the parameters and cost-effectiveness of this intervention. As such, this study aims to disclose a study that will evaluate the effectiveness and cost-effectiveness of TENS on pain intensity in women with PD. This is a protocol for an assessor-blinded randomized controlled trial that includes 174 women with PD, >18 years old, with menstrual pain greater than or equal to four points in the Numerical Rating Scale. Participants will be randomized into three groups (active TENS, placebo TENS, and educational booklet). Participants allocated to the active TENS group will receive electrical stimulation (F = 100 Hz, pulse duration = 200 μs, for 30 min). In contrast, the placebo TENS group will receive placebo stimulation (same parameters, but for only 30 s, and then the current will be ramped off over a 15-s time frame) for three consecutive months during menstruation. Participants allocated to the educational booklet group will receive instructions about health promotion and education actions related to PD. A blinded assessor will evaluate the pain intensity (Numerical Rating Scale), presenteeism (Stanford Presenteeism Scale), Health-Related Quality of Life (Short-Form 6 dimensions and SF-36), and health costs of menstrual pain. This is the first study to propose a health economic evaluation while assessing the benefits of using TENS to treat PD symptoms. It is hypothesized that active TENS will be more effective than placebo TENS or the educational booklet in improving clinical outcomes in the short-, medium- and long-term. The study will also provide information about the cost-effectiveness of TENS, which can be used by policy makers to improve PD care in public and private health systems.