Reference: Otterness et al. The Use of TENS for the Treatment of Back Pain in the Emergency Department: A Randomized Controlled Trial. AEM Aug 2025

Date: August 22, 2025

Guest Skeptic: Dr. Lauren Westafer is an Assistant Professor in the Department of Emergency Medicine at the University of Massachusetts Medical School, Baystate. She is the co-founder of FOAMcast and a researcher in pulmonary embolism and implementation science.  Dr. Westafer serves as the research methodology editor for Annals of Emergency Medicine.

Case: A 44-year-old man presents to the emergency department (ED) with low back pain after bending to pick up his child. He has pain in his left lower back that is worse when he moves. He has no fever, chills, weakness, or numbness. He has well-controlled hypertension and no history of recent antibiotic use or drug use. The patient has no midline tenderness, is without neurological deficit, and has no red flag features on history and physical exam. He took 500 mg of acetaminophen a few times without significant relief.

Background: Back pain is one of the most common reasons patients seek ED care, with an estimated 2.5 million ED visits for back pain each year. After dangerous diagnoses such as spinal epidural abscess, cord compression, and ruptured abdominal aortic aneurysm have been excluded, the next challenge for emergency clinicians is analgesia to improve the patient’s pain and mobility.

Unfortunately, there are numerous causes of musculoskeletal low back pain, rendering a single treatment course inconsistently effective for all-comers. Many pharmacological and non-pharmacological therapies have been tried with limited efficacy. 

One treatment that can be very effective but comes with very real potential harms is opioids. The American College of Emergency Physicians (ACEP) has addressed the issue of opioid use in patients being discharged home after an acute episode of pain. They give a Level C Recommendation saying:

  • Do not routinely prescribe, or knowingly cause to be co-prescribed, a simultaneous course of opioids and benzodiazepines (as well as other muscle relaxants/sedative-hypnotics) for treatment of an acute episode of pain in patients discharged from the emergency department (Consensus recommendation). 

Transcutaneous electrical nerve stimulation (TENS) is a non-pharmacological modality that administers low-intensity electrical stimulation to inhibit nociceptive pain signals. The efficacy of TENS devices in acute low back pain is uncertain.

Clinical Question: Is transcutaneous electrical nerve stimulation (TENS) more effective at relieving back pain than sham TENS?

Reference: Otterness et al. The Use of TENS for the Treatment of Back Pain in the Emergency Department: A Randomized Controlled Trial. AEM Aug 2025

  • Population: Adult ED patients (≥18 yr) with thoracic or lumbar back pain of at least moderate severity when research assistants were present (Mon–Fri, 8a–8p).
    • Exclusions: Patients with suspected spinal cord injury or infectious etiology, fractures, hemodynamic instability, allergy to standard analgesics, pacemakers, and those with skin conditions precluding TENS application were excluded.
  • Intervention: Two cutaneous TENS adhesive pads above and below the point of maximal tenderness with TENS unit set at a point just below the pain threshold and gradually increased for up to 30 minutes.
  • Comparison: Sham TENS pads applied but no electrical current. Patients were told they might or might not feel pulses.
  • Outcome:
    • Primary Outcome: Absolute reduction in pain (0–10 NRS) from baseline to 30 
    • Secondary Outcomes: Administration of rescue medications, change in pain severity, patient satisfaction with assigned treatment, and whether patients would recommend the same treatment
  • Trial: Single-center randomized controlled trial

Dr. Kara Otterness

This is an SGEMHOP, and we are pleased to have the lead author on the episode, Dr. Kara Otterness. She is originally from Illinois and graduated from Drexel University College of Medicine and completed her Emergency Medicine residency training at NYU/Bellevue. She joined the Stony Brook EM faculty in 2015. She is passionate about teaching, medical education and currently serves as one of the assistant program directors at Stony Brook.  Dr. Otterness has been a guest skeptic on SGEM#96. 

Authors’ Conclusions: “TENS was more effective than sham TENS at reducing pain severity in adult ED patients with back pain.”

Quality Checklist for Randomized Clinical Trials:

  1. The study population included or focused on those in the emergency department. Yes
  2. The patients were adequately randomized. Yes
  3. The randomization process was concealed. Yes
  4. The patients were analyzed in the groups to which they were randomized. Yes
  5. The study patients were recruited consecutively (i.e. no selection bias). No 
  6. The patients in both groups were similar with respect to prognostic factors. Yes 
  7. All participants (patients, clinicians, outcome assessors) were unaware of group allocation. No
  8. All groups were treated equally except for the intervention. Yes
  9. Follow-up was complete (i.e. at least 80% for both groups). Yes
  10. All patient-important outcomes were considered. Yes
  11. The treatment effect was large enough and precise enough to be clinically significant. Unsure
  12. Financial conflicts of interest. None

Results: The total cohort consisted of 80 patients. The mean age was 46 years. It was evenly split between female and male patients. The vast majority had lumbar pain (86%), 40% traumatic and 33% recurrent pain. Roughly half of patients had tried self-care with over-the-counter medications, and 31% had used heat.  

Key Results: TENS produced a greater reduction in 30-minute pain than sham and reduced the need for rescue meds, with higher satisfaction and similar functional measures.

  • Primary Outcome: The mean difference in change in pain scores was 1.2 (95% CI 0.5-1.9) p=0.002
  • Secondary Outcomes: Overall, secondary outcomes favoured the intervention. Rescue medications were administered to a higher proportion of patients in the sham TENS group (73% vs 45%), and more patients rated the degree of pain relief as better or much better in the TENS group (55% vs 26%). More patients in the intervention group were satisfied with their treatment (78% vs 50%).

Listen to the SGEM podcast to hear Kara respond to our five nerdy points. 

  1. Convenience Sample: This trial used a convenience sample of patients enrolled only when research assistants were available (weekday business hours). Restricting recruitment in this way creates a risk of selection bias and limits generalizability because the study population may differ systematically from all ED back-pain patients. For example, patients who present to the ED at night and on weekends may have different injury mechanisms, comorbidities, pain severity or expectations.
  2. Compromised Masking: Although the trial was designed to be patient and assessor-mask, most patients correctly guessed their group allocation (95% TENS and 83% sham). When masking is not maintained, especially for subjective outcomes like pain scores, patients’ expectations can influence reported outcomes (placebo/nocebo effects). This can inflate the apparent benefit in the intervention arm, a form of differential measurement bias. True allocation concealment and maintaining blinding integrity are central to avoiding biased estimates of effect in RCTs. However, it is difficult to think about how such an intervention could be delivered without patients guessing correctly.
  3. Clinical vs Statistical Significance: The trial’s primary outcome did reach statistical significance (mean pain reduction difference 1.2 points, 95% CI 0.5–1.9) p =0.002. However, the effect size was close to or below many published minimum clinically important difference (MCID) thresholds for acute pain of around 1.5 on a 0–10 scale. Overemphasis on statistical significance without weighing clinical relevance can lead to the adoption of interventions that improve scores in a way that is detectable to researchers but not perceptible or valuable to patients.
  4. Small Sample Size: Patient recruitment in the ED is notoriously difficult due to difficulties staffing research staff at all hours of the day and during acute conditions. The authors recruited an adequate number of patients (n=80) for their power analysis; however, this resulted in large confidence intervals and ranges. Small studies are more vulnerable to random error and chance imbalances in prognostic factors, even with randomization. This increases the likelihood that the observed effect could be an overestimate (small-study effect) and reduces confidence in the precision of the result.
  5. Single-Centred: Because the trial was conducted in a single ED, the findings may not translate directly to other practice environments. Results from a tertiary academic centre (often with more resources, specialist staff, and research infrastructure) may not reflect community EDs, rural settings, or different health systems. Patient demographics, case mix, staff expertise, and even equipment quality can influence both the feasibility of the intervention and its observed effect. Without replication in multiple, diverse sites, the applicability of this trial’s results to the broader population of ED back-pain patients remains uncertain.

Comment on Authors’ Conclusion Compared to SGEM Conclusion: We agree there’s a small, immediate benefit and less rescue medication with TENS. However, we’re more cautious about clinical significance (effect near the MCID), potential placebo/nocebo effects, and uncertain durability of the pain reduction.

SGEM Bottom Line: Although use of TENS may marginally reduce pain scores in ED patients with low back pain, the reduction is small and may be due to a placebo effect.

Case Resolution: You give the patient ibuprofen and discuss multi-modal analgesia options, physical therapy referrals, and expectations around the slow resolution of pain, as well as worrisome return precautions. The patient has no idea if their insurance covers a TENS unit and feels agreeable to discharge with NSAIDs, a physical therapy referral, and may discuss further treatment with their primary care doctor.

Dr. Lauren Westafer

Clinical Application: Because low back pain is difficult to treat and there is no single effective therapy for these heterogeneous presentations, some patients may find TENS units modestly effective. Whether it is due to the treatment itself or an elaborate placebo effect remains uncertain.

What Do I Tell the Patient?  Your back strain doesn’t show signs of something dangerous. Back pain is difficult to treat as there is a lack of evidence for any specific treatment. Often, resolution can take several weeks. Different patients report finding relief from different types of treatment. These include medications and non-pharma options. What would you like to try?

Keener Kontest: The most recent winner was Dr. Steven Stelts from NZ. He knew that in the United States, the National Violent Death Reporting System (NVDRS), the federal database for violent deaths, is housed within the Centers for Disease Control and Prevention (CDC), specifically under its National Center for Injury Prevention and Control (NCIPC).

Listen to the SGEM podcast for this week’s question. If you know, then send an email to thesgem@gmail.com with “keener” in the subject line. The first correct answer will receive a shoutout on the next episode.

Now it is your turn, SGEMers. What do you think of this episode on TENS units for back pain? What questions do you have for Kara and her team? Post your comments on social media using #SGEMHOP. The best social media feedback will be published in AEM.

Remember to be skeptical of anything you learn, even if you heard it on the Skeptics’ Guide to Emergency Medicine.

Other SGEM Episodes on Back Pain:

  • SGEM#87: Let Your Backbone Slide (Paracetamol for Low-Back Pain)
  • SGEM#173: Diazepam Won’t Get Back Pain Down
  • SGEM#240: I Can’t Get No Satisfaction for My Chronic Non-Cancer Pain
  • SGEM#304: Treating Acute Low Back Pain – It’s Tricky, Tricky, Tricky
  • SGEM#366: Relax, Don’t Do It – Skeletal Muscle Relaxants for Low Back Pain
  • SGEM#419: Welcome Back – To Another Episode on Back Pain