Ely S1, Igo S2, Clay C2, Thake D3
1Shrewsbury & Telford Hospitals NHS Trust, Physiotherapy, Telford, United Kingdom, 2Coventry University, School of Nursing, Midwifery and Health, Coventry, United Kingdom, 3Coventry University, School of Life Sciences, Coventry, United Kingdom
Background: The clinical evidence for transcutaneous electrical nerve stimulation (TENS) in the management of pain for people with knee osteoarthritis (OA) is inconclusive. Different studies use varied treatment protocols and the potential effect of the stimulation duration of each treatment has not been extensively investigated.
Purpose: To identify whether the stimulation duration of TENS in a 24-hour period has any effect on the magnitude of pain relief achieved for people with knee OA and whether it explains any of the heterogeneity observed in previous reviews.
Methods: A systematised review of trials of TENS for people with knee OA, with a random effects meta-analysis, stratified by stimulation duration into four subgroups which were TENS20 minutes, TENS30-40 minutes, TENS60 minutes and TENS>60 minutes. A search was conducted in January 2018 and included Medline, Embase, CENTRAL, AMED, CINAHL and PEDro. Study quality was assessed with The Cochrane Collaboration risk of bias tool. The outcome investigated was pain intensity. A TENS versus control comparison using post-test scores from randomised controlled trials was conducted. In addition, a change from baseline comparison was used incorporating data from comparative effectiveness studies and cohort designs.
Results: For the between groups comparison, 18 RCTs with 863 participants were included. The standardised mean difference (SMD) and 95% CI for TENS20 minutes, TENS30-40 minutes, TENS60 minutes and TENS>60 minutes were the -0.52 (-0.85,-0.19), -1.82 (-2.29,-1.35), -0.38 (-0.74,0.01) and -0.43 (-0.80,-0.06) respectively. The heterogeneity for each subgroup measured by I2 was 51%, 31%, 18% and 51% respectively. The difference between the subgroups was significant (p 0.00001). For the within groups comparison, 29 studies with 1211 participants were included. The SMD and 95% CI for TENS20 minutes, TENS30-40 minutes, TENS60 minutes and TENS>60 minutes were -1.19 (-1.44,-0.94), -2.49 (-3.10,-1.88), -0.25 (-0.51,0.02) and -0.94 (-1.71,-0.18) respectively. The difference between the subgroups was significant (p 0.00001).
Conclusion(s): A larger effect size was observed in studies of TENS for people with knee OA when a stimulation duration of 30-40 minutes in a day was used. The stimulation duration appears to explain some of the heterogeneity observed in previous meta-analyses. However, the results apply to the short-term effect of TENS only. Studies not published in the English language were excluded. The studies with longer stimulation duration used protocols involving self-application by the participant. Further research should investigate the long-term effect of stimulation duration and the potential interaction of other variables with the stimulation duration including the number of treatments used, electrical properties and co-interventions. Whether the observed effect of stimulation duration applies to other conditions requires investigation.
Implications: TENS may provide greater pain relieving effects for people with knee OA, at least in the short-term, when a stimulation duration of 30-40 minutes, no more than once a day is used. Patients struggling with pain control and adherence to active treatment plans may find this a beneficial adjunct to an initial course of treatment. The benefits of this protocol in long-term management require further investigation.
Keywords: Knee Osteoarthritis, Transcutaneous Electrical Nerve Stimulation, Pain Management
Funding acknowledgements: Funded by the NIHR with award reference MRES-2015-03-017-311 to Sarah Ely. The views expressed are those of the authors.
Purpose: To identify whether the stimulation duration of TENS in a 24-hour period has any effect on the magnitude of pain relief achieved for people with knee OA and whether it explains any of the heterogeneity observed in previous reviews.
Methods: A systematised review of trials of TENS for people with knee OA, with a random effects meta-analysis, stratified by stimulation duration into four subgroups which were TENS20 minutes, TENS30-40 minutes, TENS60 minutes and TENS>60 minutes. A search was conducted in January 2018 and included Medline, Embase, CENTRAL, AMED, CINAHL and PEDro. Study quality was assessed with The Cochrane Collaboration risk of bias tool. The outcome investigated was pain intensity. A TENS versus control comparison using post-test scores from randomised controlled trials was conducted. In addition, a change from baseline comparison was used incorporating data from comparative effectiveness studies and cohort designs.
Results: For the between groups comparison, 18 RCTs with 863 participants were included. The standardised mean difference (SMD) and 95% CI for TENS20 minutes, TENS30-40 minutes, TENS60 minutes and TENS>60 minutes were the -0.52 (-0.85,-0.19), -1.82 (-2.29,-1.35), -0.38 (-0.74,0.01) and -0.43 (-0.80,-0.06) respectively. The heterogeneity for each subgroup measured by I2 was 51%, 31%, 18% and 51% respectively. The difference between the subgroups was significant (p 0.00001). For the within groups comparison, 29 studies with 1211 participants were included. The SMD and 95% CI for TENS20 minutes, TENS30-40 minutes, TENS60 minutes and TENS>60 minutes were -1.19 (-1.44,-0.94), -2.49 (-3.10,-1.88), -0.25 (-0.51,0.02) and -0.94 (-1.71,-0.18) respectively. The difference between the subgroups was significant (p 0.00001).
Conclusion(s): A larger effect size was observed in studies of TENS for people with knee OA when a stimulation duration of 30-40 minutes in a day was used. The stimulation duration appears to explain some of the heterogeneity observed in previous meta-analyses. However, the results apply to the short-term effect of TENS only. Studies not published in the English language were excluded. The studies with longer stimulation duration used protocols involving self-application by the participant. Further research should investigate the long-term effect of stimulation duration and the potential interaction of other variables with the stimulation duration including the number of treatments used, electrical properties and co-interventions. Whether the observed effect of stimulation duration applies to other conditions requires investigation.
Implications: TENS may provide greater pain relieving effects for people with knee OA, at least in the short-term, when a stimulation duration of 30-40 minutes, no more than once a day is used. Patients struggling with pain control and adherence to active treatment plans may find this a beneficial adjunct to an initial course of treatment. The benefits of this protocol in long-term management require further investigation.
Keywords: Knee Osteoarthritis, Transcutaneous Electrical Nerve Stimulation, Pain Management
Funding acknowledgements: Funded by the NIHR with award reference MRES-2015-03-017-311 to Sarah Ely. The views expressed are those of the authors.
Topic: Pain & pain management; Musculoskeletal: lower limb
Ethics approval required: Yes
Institution: Coventry University
Ethics committee: Coventry University Applied Research Ethics Committee
Ethics number: P62031
All authors, affiliations and abstracts have been published as submitted.
