What is the landscape of evidence about the safety of physical agents used in physical medicine and rehabilitation? A scoping review

BACKGROUND: Several systematic reviews (SRs) assessing the effectiveness of superficial physical agents have been published, but the evidence about their safety remains controversial. OBJECTIVE: To identify areas where there is evidence of the safety of physical agents by a scoping review. DESIGN: Four databases were systematically searched for including English SRs that explored and reported safety in terms of adverse events (AEs) related to the application of physical agents in outpatient and inpatient physical medicine and rehabilitation settings managed by healthcare professionals, published in January 2011–29 September 2021. The severity of AEs was classified according to the Common Terminology Criteria. Then, AE findings were summarised according to the SR syntheses. Finally, the reporting of the certainty of the evidence was mapped. RESULTS: Overall, 117 SRs were retrieved. Most of the SRs included randomised controlled trials (77%) and patients with musculoskeletal disorders (67%). The most investigated physical agents were extracorporeal shock wave therapy (ESWT) (15%), transcutaneous electrical nerve stimulation (13%) and electrical stimulation (12%). No AE (35%) was reported in one-third of the included primary studies in SRs, whereas few severe AEs occurred in less than 1% of the sample. Among physical agents, ESWT showed an increased risk of experiencing mild AEs compared with the control. Most SRs reported a qualitative AE synthesis (65.8%), and few reported the certainty of the evidence (17.9%), which was mainly low. CONCLUSION: We found evidence of safety on several physical agents coming mostly from qualitative synthesis. No significant harms of these interventions were found except for ESWT reporting mild AEs. More attention to the AEs reporting and their classification should be pursued to analyse them and assess the certainty of evidence quantitatively. REVIEW REGISTRATION: https://osf.io/6vx5a/.