Quality appraisal of systematic reviews on high-intensity laser therapy for musculoskeletal pain management: an umbrella review

Musculoskeletal pain (MSP) remains one of the leading causes of disability worldwide. Recent approaches to treating this condition have prompted the development of several systematic reviews investigating the efficacy of high-intensity laser therapy (HILT), whose analgesic mechanisms are based on photobiomodulation neural inhibition, endorphin and serotonin release and anti-inflammatory effects. To assess the methodological quality, reliability, and validity of the systematic reviews (SRs) on HILT in MSP. This study is an overview of SRs (umbrella review) with an observational, retrospective, and secondary design. The search considered PubMed, Scopus, Web of Science, CINAHL, Embase, Cochrane Library, ScienceDirect, and Google Scholar databases (updated October 23, 2024). The primary focus was on the methodological quality of the reviews and their reporting of pain intensity results. The HILT effects on pain intensity were reported using mean differences (MD) or standardized mean differences (SMD). The quality assessment was conducted using the A Measurement Instrument to Assess Systematic Reviews 2 checklist (AMSTAR-2), and the findings were synthesized narratively. The MD and SMD obtained from all reviews were presented using forest plots. The Shapiro-Wilk normality test assessed MD and SMD distributions for pain intensity across meta-analyses. The average MD and SMD, along with their respective confidence intervals (CI), were estimated and presented based on the aggregate study outcomes. Twenty SRs were included, fourteen of which conducted meta-analyses covering diverse musculoskeletal disorders such as knee osteoarthritis, epicondylalgia, myofascial pain, frozen shoulder, plantar fasciitis, neck, and low back pain. The primary databases used were PubMed, Web of Science, and the Cochrane Library. The AMSTAR-2 average score was 12.9 points (+/- 1.8), indicating varying methodological quality with one or two criteria resulting in low or critically low. HILT's best analgesic effects are observed in frozen shoulder disorder (MD = -2.23 cm; 95% CI:-3.3,-1.2; p < 0.01), knee osteoarthritis (MD = -1.9 cm; 95% CI:-2.0,-1.8;p < 0.01), low back pain (MD = -1.9 cm; 95% CI = -2.9,-1.0; p < 0.01), and myofascial pain (MD = -1.9 cm; 95% CI:-2.6,-1.2; p < 0.01). Largest effect sizes are for neck pain (SMD = 2.1; 95% CI = 1.2,3.0, p < 0.05) and low back pain (SMD = 1.1 (95% CI = 1.4,0.8; p < 0.01). This review underscores the generally low to critically low methodological quality of SRs on HILT, as assessed by AMSTAR-2. Key areas for improvement for future SRs of RCTs include addressing publication bias, disclosing funding sources, and enhancing search strategies and discussions on heterogeneity. The scarcity of RCTs for conditions such as temporomandibular disorders, carpal tunnel syndrome, and myofascial pain highlights the need for further research. SRs on spinal disorders, frozen shoulder, and neck pain demonstrated the most favorable analgesic effects, providing valuable insights for clinical practice and future RCTs.