Low-Level Laser Therapy including Laser Acupuncture for Non-Specific Chronic Low Back Pain: Systematic Review and Meta-Analysis
Article information
Abstract
Low-level laser therapy including laser acupuncture (LLLT/LA) has been widely used for non-specific chronic low back pain (NCLBP). However, there is no critically appraised evidence of its potential benefits. This study aimed to evaluate the effectiveness of LLLT/LA for NCLBP. There were 12 databases (MEDLINE, CENTRAL, EMBASE, KoreaMed, KMBASE, KISS, NDSL, KISTI, OASIS, CNKI, CiNII, J-stage) searched for randomized controlled trials using LLLT/LA for NCLBP up until June 2019. The primary outcome was pain intensity and functional status/disability due to NCLBP. A random-effects meta-analysis was conducted on 20 studies involving 1,323 participants. LLLT/LA showed a significant positive effect on pain relief scores compared with sham treatments (SMD −0.51, 95% CI: −0.88 to −0.13; χ2 = 31.12, I2 = 74%). Alone, the therapy showed a significant positive effect on function/disability scores (30 participants, MD −11.90, 95% CI: −17.37 to −6.43). As an add-on treatment, it showed a significant positive effect on pain relief (80 participants, MD −5.10, 95% CI: −9.31 to −0.88; χ2 = 28.99, I2 = 97%) and improved function/disability scores (120 participants, MD 5.44, 95% CI: 2.19 to 8.68; χ2 = 4.07, I2 = 75%). Among 20 studies, 9 studies reported no adverse events and 1 study reported mild adverse events. LLLT/LA may be an alternative or add-on treatment for NCLBP.
Introduction
Low back pain (LBP) is a common musculoskeletal disorder affecting 80% of people at some point in their lives. It is estimated that 10% to 20% of affected adults develop symptoms of chronic LBP (CLBP) lasting over 12 weeks [1]. A survey on the use of Korean Medical Institutions and consumption of Korean Herbal Medicine, conducted by the Korean Ministry of Health and Welfare in 2011 and 2017, reported that patients with LBP accessed Korean medical institutions the most, and accounted for 12.89% in 2011 and 52.7% in 2017 [2,3]. Non-specific chronic low back pain (NCLBP) is defined as pain lasting over 12 weeks with no clear underlying etiology. Aging is associated with lower recovery rates and higher levels or chronicity and severity [4]. According to the bio-psychosocial model, chronic pain is associated with biological, psychological, and social factors such as distress (depression, anxiety, and fear), self-efficacy, smoking, drinking, and working life [5]. Therefore, while NCLBP is not life-threatening, it reduces a patient’s quality of life.
Low-level laser therapy including laser acupuncture (LLLT/LA) induces a photochemical reaction in cells (biostimulation or photobiomodulation) to aid tissue repair and relieve pain [6]. In 2017, the American College of Physicians developed guidelines to provide clinical recommendations for non-invasive treatment of LBP, and strongly recommended that non-pharmacological treatments including LLLT should be considered for patients with CLBP [7–9].
To date, there have been no studies about LLLT/LA for NCLBP that incorporated data collected in Korea, China, and Japan; this study addressed this and critically evaluated the efficacy of LLLT/LA for NCLBP.
Materials and Methods
This systematic review was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) [10]. The protocol for this systematic review was prospectively registered on PORSPERO CRD42019140419.
Database search and study selection
There were 12 bibliographic databases searched up until June 2019: MEDLINE (PubMed), EMBASE (Ovid), the Cochrane Central Register of Controlled Trials (CENTRAL), Korean database (KoreaMed, KMBASE, KISS, NDSL, KISTI, OASIS), the China National Knowledge Infrastructure Database (CNKI), and Japanese databases (CiNII, J-STAGE).
The search strategy followed the study protocol. The search terms comprised of 2 parts, LLLT/LA (e.g., laser, laser acupuncture, laser puncture, laser needle, low-dose laser acupuncture, LLLT, low-level laser, laser therapy, laser treatment) and CLBP (e.g., lower back pain, sciatica, radiculopathy, lumbago, backache, back pain, lumbo-sacral, NCLBP). To increase the sensitivity of the search for NCLBP, concepts such as radiculopathy and sciatica were included. In some cases, the LLLT/LA parameters were classified, however, in the case of the lower back, it was difficult to avoid using acupuncture points during treatment due to their high density of use. Moreover, laser treatments have an “Alpha-phenomenon” effect that shows an indirect biostimulation effect on the surrounding tissues. In this review, all randomized controlled trials (RCTs) where LLLT/LA was performed were analyzed. Observational, cohort, case reports, case series, non-RCT, animal and experimental studies were excluded from this review.
Two reviewers independently screened the studies and after analysis made the final decision of which studies to include.
Data extraction and assessment of risk bias
Study data including the intervention description, baseline, demographics, and values for outcomes was extracted by 2 reviewers and checked for accuracy by a third reviewer. The primary outcomes were: (1) Pain intensity measured on a visual analog scale (VAS) or the numeric rating scale (NRS) and (2) Functional status/disability measured by the Oswestry disability index (ODI) or Japanese orthopaedic association (JOA) scale. The secondary outcomes included range of motion (ROM), results from the Modified Schober test, global assessment of quality of life, and negative side effects.
The study quality was assessed according to the criteria described in the Cochrane Handbook for Systematic Review of Intervention, and RCTs were assessed using the Cochrane Bias Risk tool.
Statistical analysis
The Review Manager (e.g., Cochrane Collaboration Software, RevMan version 5.3.5) was used for data management and statistical analysis. For continuous data, treatment effects were expressed as a mean difference (MD) or standardized mean difference (SMD) with a 95% confidence interval (CI) level. Meta-analysis was used to combine the results of trials using a random-effects model. Data was presented as a forest plot. Heterogeneity was evaluated using heterogeneity test (I2 statistic).
Results
Description of the included studies
A total of 1,019 studies were retrieved from 12 online databases. After screening the articles and removing duplicates, 20 studies (RCTs) were selected according to the inclusion criteria [8,9,11–28], and were conducted in 11 countries with a combined total of 1,323 patients (Fig. 1).

A PRISMA flow diagram of the literature screening and selection processes.
MEDLINE, PubMed; CENTRAL, the Cochrane Central Register of Controlled Trials; EMBASE, Ovid; CNKI, the China National Knowledge Infrastructure Database; CiNII, Scholarly and Academic Information Navigator, pronounced like “sigh-knee”; J-STAGE, Science and Technology Agency Electronic journal platform; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-analyses.
Intervention analysis
The 20 studies consisted of 13 RCTs comparing LLLT/LA with sham laser therapy [8,9,11–21], 2 trials comparing LLLT/LA with no treatment [24,26], 4 trials comparing LLLT/LA used as add-on therapy with a control group [24,25,27,28], and 1 study which compared the effects of 2 laser treatment methods on different conditions [23].
Of these 20 studies, 2 trials were 3-arm RCTs, 1 compared low-dose laser treatment with high-dose laser treatment, and sham laser treatment [13], 1 compared LLLT and exercise in combination with ultrasound and exercise in combination, and to exercise alone [24]. Three of the studies could not be included in the analysis because the laser treatment methods varied between individual groups [13,22,23]. The characteristics of the included studies are listed (Tables 1–4).
Furthermore, LLLT/LA is a treatment method that uses a laser device, therefore, the following laser parameters and treatment characteristics were recorded: wavelength, power, energy density, beam size, number of treatments, treatment time, treatment sessions and treatment intervals. Where particular laser parameters were not reported, values were calculated from formulas using the reported parameters. The characteristics of the laser parameters are listed (Tables 5–8).
Primary outcomes
Comparing LLLT/LA with sham-LLLT/LA therapy
With regards to pain, 4 of the 13 studies were excluded. Three studies evaluated pain relief by the amount of change in the VAS score without reporting exact values [9,14,17], and 1 study described the results by the degree of change in the chronic pain index [21]. In 9 studies involving 495 participants, the VAS and NRS were used to evaluate the degree of pain relief, and LLLT/LA significantly reduced pain compared with sham treatment (SMD −0.51, 95% CI: −0.88 to −0.13; χ2 = 31.12, I2 = 74%; Fig. 2).

The effectiveness of LLLT/LA versus sham LLLT including LA on pain relief
CI, confidence interval; Df, degree of freedom; IV, information value; LA, laser acupuncture; LLLT, low-level laser therapy.
With regards to function/disability, 4 out of 13 studies evaluated outcomes using ODI values [8,11–13]. In 4 studies (277 participants), LLLTs with LA had no significant effect compared with sham treatment (MD −2.68, 95% CI: −9.15 to 3.79; χ2 = 38.40, I2 = 92%; Fig. 3).
Comparing LLLT/LA as alone with other therapies
With regards to pain, 2 studies applied LLLT/LA alone; 1 study compared LLLT/LA with ultrasound treatment [24], and 1 study compared LLLT/LA with chu-na therapy [26]. There was significant pain relief in the study where LLLT/LA alone was compared with ultrasound therapy alone (30 participants, MD −1.12, 95% CI: −2.09 to −0.15). In the study comparing LLLT/LA with chu-na therapy, there was no significant effect on pain relief (106 participants, MD 0.03, 95% CI: −0.31 to 0.37; Fig. 4).

The effectiveness of LLLT/LA as alone on pain relief
CI, confidence interval; Df, degree of freedom; LA, laser acupuncture; LLLT, low-level laser therapy; IV, information value.
With regards to function/disability, 1 study showed a significant positive effect on the ODI between LLLT/LA alone and ultrasound therapy alone [26] (30 participants, MD −11.90, 95% CI: −17.37 to −6.43; Fig. 5).
Comparing LLLT/LA as add-on treatment
With regards to pain, 2 studies where LLLT/LA was applied as add-on treatment showed a significant positive effect on pain relief [24,28] (80 participants, MD −5.10, 95% CI: −9.31 to −0.88; χ2 = 28.99, I2 = 97%; Fig. 6).

The effectiveness of LLLT/LA as add-on treatment of pain relief
CI, confidence interval; Df, degree of freedom; LA, laser acupuncture; LLLT, low-level laser therapy; IV, information value.
With regards to function/disability, 2 studies used the JOA scale to evaluate outcomes [25,27], and a further 2 used the ODI [24,28]. A higher JOA scale score and a lower ODI score post-treatment indicated increased effectiveness at improving dysfunction. As an add-on treatment, LLLT/LA significantly improved function and disability in the studies evaluated using the JOA scale (120 participants, MD 5.44, 95% CI: 2.19 to 8.68; χ2 = 4.07, I2 = 75%). In the studies using the ODI, there was no significance noted (80 participants, SMD −0.81, 95% CI: −2.74 to 1.13; χ2 = 14.05, I2 = 93%; Figs. 7 and 8).

The effectiveness of LLLT/LA as add-on treatment on function and disability measured by JOA
CI, confidence interval; Df, degree of freedom; IV, information value; JOA, Japanese orthopaedic association; LA, laser acupuncture; LLLT, low-level laser therapy.
Adverse reactions and side effects
Ten RCTs reported adverse reactions/negative side effects. Of these, 9 reported no adverse reactions [9,11,13,14,17,18,20,21,23], and in 1 RCT, adverse reactions were reported as mild “warmth” which occurred more often during treatment in the active group [8]. No adverse reactions were noted in the other 10 studies [12,15,16,19,22,24–28].
Risk of bias
The risk of bias was assessed for the 20 RCTs according to the Cochrane handbook (Figs. 9 and 10).
Random sequence generation
Low risk was observed in 12 studies [8,11–14,17,18,20,22–24]. The other 8 studies were evaluated as unclear risk [9,15,19,21,25–28].
Allocation concealment
Low risk was observed in 12 studies [8,11–14,17,18,20,22–24]. The other 8 studies were evaluated as unclear risk [9,15,19,21,25–28].
Blinding of participants and personnel
Two studies were evaluated as high risk, which clearly stated that blinding of the study was not possible for the therapist [14,23]. Eight studies were deemed low risk as they reported that therapist was independently blinded to the study [8,9,11–13,16,17,20]. The other 10 studies were evaluated as unclear risk [15,18,19,21,22,24–28].
Blinding of outcome assessment
Low risk was observed in 10 studies that mentioned independent researcher and evaluators [11–14,16,17,20,23,24,28]. The other 10 studies were classified as unclear risk [8,9,15,18,19,21,22,25–27].
Incomplete outcome data
Low risk was observed in 17 studies that had no dropouts or similar occurrence of missing values between groups. The other 3 studies were evaluated as unclear risk [17,21,22].
Selective reporting
Five studies that reported results according to the previous protocols were classified low risk [12,13,17,18,24]. Two studies reported an incomplete result and was evaluated as high risk [9,21]. There were 13 studies that did not report the protocol and were classified as unclear risk [8,11,14–16,19,20,22,23,25–28].
Discussion
The US Bureau of Statistics published “An Aging World: 2015” which predicted that from 2025 to 2050, the older population is projected to almost double to 1.6 billion globally, whereas the total population will grow by just 34% over the same period [29]. When life expectancy is increasing and aging is rapidly progressing, pain is 1 of the main indicators of quality of life. Chronic pain not only limits daily life at work/home, it also impairs mental health and negatively affects the economy. Several South Korean surveys (the Survey on the Elderly, the National Health and Nutrition Survey, and the Aging Research Panel Survey) reported that 90% of pain in men and women over 60 years of age occurred in the musculoskeletal area, with lower back pain, and knee pain being the most prevalent [30].
NCLBP is a condition where non-pharmaceutical treatment is recommended over pharmaceutical therapy. Non-steroidal anti-inflammatory analgesics and/or muscle relaxants are used to alleviate symptoms. However, these forms of pharmaceutical therapy require a risk-benefit assessment due to potential side effects (increased risk of renal failure, gastric ulcers, and cardiovascular disease) [31].
LLLT/LA is a non-invasive treatment without the risk of pain or infection. It has been used to manage chronic pain in Korean medical clinics and has high patient satisfaction. However, it is difficult to prove its efficacy because each RCT is conducted under different conditions using different laser machine specifications. In this systematic review, as many databases as possible were used from the USA, Europe, Korea, China, and Japan. The efficacy of LLLT/LA on NCLBP was investigated under 3 conditions: comparison with a control group, comparison with other treatments, and efficacy as an add-on treatment.
The 20 studies that were selected covered 11 countries and included a total of 1,323 patients. Among the 13 studies comparing LLLT/LA with sham treatment, 7 mentioned a positive effect on pain reduction in the experimental group compared with the control group. As a result of VAS score analysis of the 9 studies that could be analyzed, a significant positive effect on pain relief was confirmed. In the 4 studies that could not be analyzed concerning the improvement of function/disability, the result of the ODI analysis showed no significance. There was a significant positive effect on pain relief and function/disability in the study where LLLT/LA group was compared with ultrasound treatment. When compared with chu-na treatment, there was no significant improvement in pain relief between the 2 groups. However, each group did show significant pain improvement after treatment. Further study is required to fully assess these outcomes. LLLT/LA as an add-on treatment showed a significant positive effect on pain relief. With regards to the improvements in function/disability, the 2 studies using the JOA scale showed a significant positive effect and the 2 studies using the ODI scale showed no significant positive effect. As a result, LLLT/LA showed a significant positive effect on pain relief and function/disability improvement during a short period.
This study is not without its limitations. Firstly, with increasing age came a higher association of LBP with the underlying disease, therefore the number of studies on NCLBP was small compared with the total number of studies retrieved. All Japanese studies had to be excluded due to inclusion of LBP associated with the underlying disease. Secondly, chronic pain is correlated to quality of life. However, the treatment and evaluation periods in most studies were too short to evaluate any long-term biopsychosocial outcomes. Therefore, this should be considered when designing future studies to evaluate the possibility of LLLT/LA as a therapy for chronic pain management in an aging era. Finally, many of the studies presented were not of high quality.
This study determined that LLLT/LA may be an effective and safe intervention for NCLBP. However, there were no studies conducted under the same treatment conditions, therefore further well-designed studies are required to determine which treatment condition is most effective. Therefore, moving forward, establishing a more accurate treatment method will require well-designed studies.
Conclusion
This systematic review and meta-analysis suggest that LLLT/ LA may be considered as an alternative or add-on treatment for NCLBP. LLLT/LA has a significant positive effect on reducing pain and improving the function/disability and has rare serious adverse events.
Notes
Conflicts of Interest
The authors have no conflicts of interest to declare.