The aim of this study is to determine the efficacy of low-level laser therapy (LLLT) in reducing acute and chronic neck pain as measured by the visual analog scale (VAS). A systematic search of nine electronic databases was conducted to identify original articles. For study selection, two reviewers independently assessed titles, abstracts, and full text for eligibility. Methodological quality was assessed using the Detsky scale. Data were analyzed using random-effects model in the presence of heterogeneity and fixed-effect model in its absence. Heterogeneity was assessed using Cochran’s Q statistic and quantifying I2. Risk ratios (RR) with 95 % confidence intervals (CI) were reported. Eight randomized controlled trials involving 443 patients met the strict inclusion criteria. Inter-rater reliability for study selection was 92.8 % (95 % CIs 80.9–100 %) and for methodological quality assessment was 83.9 % (95 % CIs 19.4–96.8 %). Five trials included patients with cervical myofascial pain syndrome (CMPS), and three trials included different patient populations. A meta-analysis of five CMPS trials revealed a mean improvement of VAS score of 10.54 with LLLT (95 % CI 0.37–20.71; Heterogeneity I2 = 65 %, P = 0.02). This systematic review provides inconclusive evidence because of significant between-study heterogeneity and potential risk of bias. The benefit seen in the use of LLLT, although statistically significant, does not constitute the threshold of minimally important clinical difference.
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We thank Andrea McLellan and Jennifer McKinnell, Health Sciences Librarians, for their guidance in developing a comprehensive search strategy. We also thank Tahrin Mahmood, for masking study results and authors affiliations. We are grateful to Kaelan Moat, Dr. Bingshu Chen, and Dr. Rob Brison for their insightful comments and suggestions.
Conflict of interest
There are no competing interests.
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