Transcutaneous Electrical Nerve Stimulation for Back Pain in the Emergency Department (TENS-ED)

The effectiveness of Transcutaneous Electrical Nerve Stimulation (TENS) to reduce pain scores for patients with acute back pain in an ambulatory emergency department (ED) population will be examined in this dual-center, cluster randomized, controlled, open-label study.

Back pain is one of the top 5 most common ED presenting complaints, accounting for approximately 3% of all ED visits. It is estimated that 85% of these patients will leave the ED with a non-specific diagnosis, such as mechanical low back pain, and will recover within 4-6 weeks. Unfortunately, treatment for these patients is limited and often consists of NSAIDs, acetaminophen, and opioids if in significant pain.

TENS is a non-pharmacological option for the treatment of pain. The mechanism of its effect is based on the gate control theory of pain; stimulation of large, myelinated fibers reduces transmission of pain through smaller, nociceptive C-fibers through inhibitory actions of interneurons. It is very safe, with very few reported adverse effects and a short list of contraindications.

In 2015, a Cochrane review examined the benefit of TENS in acute pain, which was defined as less than 12 weeks. Their review demonstrated tentative evidence of benefit in reducing pain, although due to the small sample sizes of the encompassing trials and the inability to blind, definitive conclusions are impossible.

Research question: "In patients in the ED triage area,18 years of age or older with acute or acute-on-chronic back pain for less than three weeks, does 30 min of transcutaneous electrical nerve stimulation reduce pain scores as compared to standard care alone?"

Eligibility Criteria:
Inclusion Criteria:

* Age 18 years or older.
* Acute or acute-on-chronic back pain, defined as less than 3 weeks of increased symptoms.
* Canadian Triage and Acuity Scale (CTAS) level 3-5 in ambulatory section of emergency department8.
* Projected wait-time of at least 30 minutes.
* Comfortable with communication in English. Unfortunately, currently, we do not have the capacity or funding to hire a translator to translate our study documents or communicate with potential study participants.

Exclusion Criteria:

* Back pain "red flags" on initial history. These include:

  * Patient reported fever.
  * Recent direct blunt or penetrating trauma to the back, perceived by the patient to be the cause of acute pain or exacerbation of chronic pain.
  * Bilateral radicular symptoms.
  * Changes in ability to empty bladder or urinary incontinence since onset of back pain.
  * Incontinence of stool.
  * Saddle anesthesia.
  * Intravenous drug use within the last 30 days.
* History of spinal cord injury.
* Epilepsy.
* Abnormal triage vital signs:

  * Temperature greater than 38 C
  * Abnormal blood pressure (BP) defined as systolic BP less than 90 or over 180.
  * Tachypnea with respiratory rate (RR) greater than 22.
* Active pregnancy (patient warning on product label)
* Canadian Triage and Acuity Scale (CTAS) level 1-2.
* Implanted pacemaker or neurostimulation device.
* TENS unit in use by another patient at time of screening
* Wound, abrasion, rash over where TENS pads will be placed.