Paper 5/2012

Clin Rheumatol. 2010 Aug;29(8):905-10.

Is low-level laser therapy effective in acute or chronic low back pain?

Ay S, Doğan SK, Evcik D.


The purpose of this study was to compare the effectiveness of low-level laser therapy (LLLT) on pain and functional capacity in patients with acute and chronic low back pain caused by lumbar disk herniation (LDH). LLLT has been used to treat acute and chronic pain of musculoskeletal system disorders. This study is a randomized, double-blind, placebo-controlled study. Forty patients with acute (26 females/14 males) and 40 patients with chronic (20 females/20 males) low back pain caused by LDH were included in the study. Patients were randomly allocated into four groups. Group 1 (acute LDH, n = 20) received hot-pack + laser therapy; group 2 (chronic LDH, n = 20) received hot-pack + laser therapy; group 3 (acute LDH, n = 20) received hot-pack + placebo laser therapy, and group 4 (chronic LDH, n = 20) received hot-pack + placebo laser therapy, for 15 sessions during 3 weeks. Assessment parameters included pain, patients’ global assessment, physician’s global assessment, and functional capacity. Pain was evaluated by visual analog scale (VAS). [corrected] Patients’ and physician’s global assessment were also measured with VAS. Modified Schober test and flexion and lateral flexion measures were used in the evaluation of range of motion (ROM) of lumbar spine. Roland Disability Questionnaire (RDQ) and Modified Oswestry Disability Questionnaire (MODQ) were used in the functional evaluation. Measurements were done before and after 3 weeks of treatment. After the treatment, there were statistically significant improvements in pain severity, patients’ and physician’s global assessment, ROM, RDQ scores, and MODQ scores in all groups (p < 0.05). However, no significant differences were detected between four treatment groups with respect to all outcome parameters (p > 0.05). There were no differences between laser and placebo laser treatments on pain severity and functional capacity in patients with acute and chronic low back pain caused by LDH.

The paper above triggered the following Letter to the Editor of the journal, not requesting publication, necessarily, but as a piece of information. It was not published.

To the Editor of
Clinical Rheumatology

Dear Editor,

We are contacting you regarding the paper by Ay et al in Clin Rheumatol, published online 23 April 2010, DOI 10.1007/s10067-010-1460-0.

The treatment modality evaluated in this study is low level laser therapy (LLLT). This modality has much potential in rheumatology, being non-invasive and essentially without side effects. It is therefore important that studies are carried out in a rigorous manner.

The Ay study has some merits in that it has used a fairly large study group (although one could argue that 20 participants per treatment group is small for this type of study and unlikely to show a difference between groups if it exists) and carried out utilising MRI in all patients to make the evaluation more objective. It is rather peculiar though, to compare acute and chronic low back pain in one RCT as these are different biological entities. However, the most significant issues that we have regarding the study by Ay and colleagues, is the actual treatment applied and reported. We believe that the LLLT methodology is reported poorly and indicating that the application was not carried out according to guidelines now internationally accepted. By undertaking the research without regard to internationally accepted guidelines, and by not fully reporting the treatment parameters is therefore doing more harm than good in the evaluation of a promising therapeutic alternative.

A summary of the most important failures of the paper is attached for your information. Our letter is not necessarily aimed for publishing, but rather to inform the editorial staff of your journal about the requirements when it comes to performing and reporting low level laser trials.

A major problem for medical journals appears to be finding qualified reviewers in the field of low level laser therapy. We may be able to give you contact details of such persons; not necessarily qualified in evaluating the medical aspects but certainly the laser aspects. Adding one such person as a reviewer for all laser therapy papers would increase the quality of published papers.

Best regards

Jan Tunér DDS, Swedish Laser Medical Society

Liisa Laakso, Griffith University, Australia

Jan M Bjordal, PhD, University of Bergen, Norway

Ernesto Cesar Pinto Leal Junior, PhD, PT, University of Bergen, Norway

Phil Gabel, PT, Australia

Peter A. Jenkins, MBA, Dir. Education & Technology, SpectraMedics Pty Ltd

James Carroll, Thor Photomedicine,UK

Lars Hode, DSc, Swedish Laser Medical Society

Comments on the Ay study

1. There are many parameters at work when laser light interacts with biological tissues. Changing one of the many also changes the clinical outcome. It is therefore very important to report all parameters, as will be discussed below.

2. The abstract of the present paper does not include any of those parameters, making an evaluation of the study difficult. A majority of those taking an interest in this paper will only read the PubMed abstract. Consequently it is essential for these parameters to be included.

3. The authors have used different Pulse Repetition Rates (PRR) for chronic and acute cases. The knowledge about the effect on pulsing is scant, to say the least. In vitro studies clearly show that the effects change with different PRRs, but the in vivo literature does not give any clues to the benefits of pulsing. No discussion about the role of pulsing is included in the paper.

4. The authors indicate an ‘energy’ of approximately 40 J/cm^2. The unit of measure “J/cm^2” is the dose (fluence) and not the energy. Energy is expressed in J (joules). Energy is one of the parameters that should be reported in an acceptable study.

5. In a scientific study the actual output must be independently verified since manufacturer data are not reliable and output actually differs in the same assembly line. Diodes also lose power with ageing.

6. The rationale for choosing the reported dose is not discussed and therefore appears to be arbitrary. Whether the 40 J/cm^2 was for one point or the total dose is unclear, since the authors write “two to four points”. The product of laser power output and irradiation time provides the energy. The exact anatomical sites treated are also unclear. The study treats back pain as a homogenous group with no references to sub groups or sub-categories, a distinction that may have influenced the effectiveness of the intervention.

7. The references discussed are either dated or cite work that is inaccurate or incomplete, thus suggesting some unfamiliarity by the authors with the literature. For example, reference 18 is from the 1980s and using 1 mW HeNe; reference 16 again is HeNe laser; and reference 12 has long since been rejected as inadequate and biased. Very few relevant and recent papers are discussed and the contribution of different wavelengths, doses and applications modes is lacking. The authors also misinterpret reference 4 as negative, while the conclusion actually is positive.

8. A summary of the beneficial dose ranges for musculoskeletal indications has for several years been published by The World Association for Laser Therapy. These may not have been known to the authors. Recent papers adhering to these recommendations for low back pain demonstrate positive outcomes, e.g. Konstantinovic et al, also using MRI to verify LBP diagnoses. It is possible that the dose applied by the Ay group is not appropriate in the context applied in this research.