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Letters and Responses |
Bjordal raises several interesting points regarding low-level laser therapy (LLLT), points that do not conflict with my own findings. First, he has identified that LLLT manufacturers often provide insufficient evidence to support the use of this intervention. In fact, many clinical trials are conducted using dosing as recommended by the manufacturer.1Second, he states that laser "may yet be very effective when used properly for this condition." This statement reflects 2 of the points I tried to reinforce strongly in my article:
Bjordal et al identify that the "rationale behind the selection of application technique and treatment parameters, such as power density, size of exposure, timing or treatment frequency, often remains unclear."1 My own Evidence in Practice article arrived at this same conclusion: "The most effective method of treatment...needs to be established before the efficacy of LLLT can be determined."2(p1166)
I would like to respond to 2 of Bjordal's comments on the selection of my search criteria and the selection of appropriate dose and treatment procedure for LLLT.
Evidence in Practice articles were designed to illustrate how working clinicians can efficiently use literature to make decisions regarding patient care. For this reason, the search criteria for these articles are often narrowed in order to meet the time constraints of the clinician. Bjordal argues that the age of a study is not a valid criterion for exclusion. Portney and Watkins,3 however, have identified that it is generally practical to limit the review of older articles, so as to not review every historical document in the field. If not confined in some manner, a review of literature can go on indefinitely.3
For this reason, I selected a parameter of 10 years, with the assumption that the more recent articles would include an analysis of older research. For example, the systematic review by Trudel et al4 was retrieved in my search for evidence. This systematic review examined a variety of interventions for lateral epicondylitis. In particular, 9 studies were relevant to laser therapy and LLLT. The authors reported at least level 2b evidence (based on the Sackett system5) that showed laser therapy to be ineffective in the treatment of lateral epicondylitis. Of the 9 studies examined by Trudel et al, 7 were conducted more than 10 years ago.
Bjordal also raises the question of using the Cochrane Library and CINAHL database. The CINAHL database, unlike MEDLINE, is not available for free to the public. For clinicians without complimentary access to CINAHL, the cost may prohibit the use of the database.* In addition, MEDLINE has a large database of indexed journals. In fact, it indexes all but 1 journal included as references in Bjordal's letter to the editor. On the other hand, CINAHL does not index Laser & Technology, Pain, Photomedicine and Laser Surgery, or the Journal of Photochemistry and Photobiology. Although the Cochrane Library does provide free access to abstracts, costs are associated with access to full-text articles. Once again, the cost for full articles, currently $25, may prohibit use of this tool by clinicians. MEDLINE, on the other hand, provides access to the full text of many journals at no additional cost to the user.
As my final point regarding my search criteria, I was interested only in studies relevant to the lateral epicondylitis. This is the location of 25% to 40% of injuries seen in my clinical practice and was the diagnosis in which I was most interested regarding LLLT. Because I wanted to compare "apples to apples," I limited my selection of articles to only those pertinent to "lateral elbow."
This approach was further validated after reading the 2001 systematic review by Bjordal et al.1 This review highlights that treatment varies for different tendons based on laser type, distance from the skin surface, and volume of injured tissue.
For this reason, different treatments need to be provided for tendon injuries in different locations. In contrast, the articles referenced by Bjordal in his letter to the editor covered topics, injuries, or diagnoses that were not pertinent to my patient population: Achilles tendinitis,6 patellar tendinitis,7 ultrasonographic research on tendon thickness and depth,8 edema,9 the effect of steroids on laser therapy, and chronic joint disorders.11 Journal articles about these injuries or diagnoses would not efficiently help to answer a clinical question about the efficacy of LLLT in the treatment of lateral epicondylitis, although they may be pertinent for other research or Evidence in Practice articles.
I concur with Bjordal that reviews of articles in the literature do not answer the question of proper dose or treatment procedure. In a study not identified by my own literature review, Bjordal et al1 attempted to identify a dose-response pattern for several types of tendinopathy: epicondylitis, rotator cuff tendinopathy, patellar tendinopathy, Achilles tendinopathy, and plantar fasciitis. They conducted a systematic review of trials using LLLT published after 1980. The search was conducted on MEDLINE, EMBASE, and the Cochrane Library, in addition to a hand search of physical therapy journals in English and Scandinavian languages. Twenty trials were identified with the keyword "tendinopathy." Of those 20 trials, 13 met the inclusion criteria. When all studies were taken as a whole, the authors found a 22% effect in favor of LLLT over placebo. owever, when the authors eliminated the studies that they determined did not utilize "optimal dosage," the effect increased to 32% in favor of LLLT over placebo.
Of the 13 included trials, only 7 were relevant to epicondylitis. The authors did not differentiate the results of epicondylitis from other tendinopathies. In addition, the authors did not separate the diagnosis of medial and lateral epicondylitis, conditions that may involve application of treatment to tendons at different depths, with different cross-sectional diameters, and so on. The use of optimal dosage in the review is a "suggested optimal range" determined by the authors. The optimal ranges were developed from the results of 5 in vitro studies examining increases in collagen production and estimations of tendon characteristics (depth, cross-sectional diameter, and area). Although in vitro studies are useful for developing guidelines for treatment, future studies should be conducted with live subjects. Human tissues can significantly vary in distance from the skin surface to the target tissue, in vascularity, and in amount of tissue injury.
Although the study by Bjordal et al is the first study I have reviewed that identified actual dose ranges, I would like to see additional studies that validate or refute "optimal dosage" as determined by Bjordal et al. They found only 7 studies that met inclusion criteria for epicondylitis. Of those 7 studies, only 4 met the "suggested" optimal power density and dose ranges as determined by the authors. Validation of the use of laser in epicondylitis, therefore, was determined by 4 articles. The systematic review by Trudel et al,4 although not dose specific, analyzed 9 studies and found laser to be ineffective.
I believe that identifying a need for additional research regarding LLLT is not a negative conclusion. Instead, it challenges those who manufacture lasers, those who use lasers, and those interested in new treatment options to continue to design high-quality research studies to either validate or refute the benefits of this intervention. I thank Bjordal for his insightful comments about my article. I look forward to continuing my own research on this intervention and hope other clinicians and researchers will conduct studies as well.
S Maher, PT, DScPT, OMPT, is Assistant Professor, Oakland University, Oakland, Mich, and Physical Therapist, Michigan Rehabilitation Specialists, Hamburg, Mich
(sfmaher{at}oakland.edu)
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