ARE ALL THE NEGATIVE STUDIES REALLY NEGATIVE?

抄録

This article presents an analysis of a number of frequently cited studies on the effects of low level laser therapy (LLLT). In many of these studies, the analysis uncovered one or more reasons for the negative findings reported, the most common being the use of extremely low doses. Other reasons included faulty inclusion criteria, inaccurate control group definition, ineffective methods of therapy, inadequate attention to systemic effects and tissue condition, and low incident power density. A weakness often encountered in these studies is their failure to provide sufficient data on laser parameters. Since negatively inclined studies such as these are often quoted as “proof” of the ineffectiveness of LLLT, it is important that they be subjected to a proper critical analysis. 1,400 articles were reviewed for this analysis, the emphasis being on double-blind studies. Of the 135 localized double-blind studies, 85 reported positive findings. Though important, the critical examination of scientific literature is decidedly unglamorous. It involves hours and days of searching through a wide variety of different sources, and by no means all information is yet available on-line. There are numerous pitfalls, too, especially for those who opt to read abstracts only - criticism of sources is impossible unless an article can be studied in its entirety. Basing an opinion from abstracts obtained from online services such as Medline is risky. In addition, only a very small number of the early LLLT research reports are available from the major databases. In the following analysis of the available literature, we have chosen to analyze those studies unable to demonstrate the effectiveness of LLLT. Although priority was given to double-blind studies, non-double-blind studies were also included in certain typical cases. Certain studies were also included merely on the grounds that they are among the most frequently cited. The 1,400 articles reviewed for this analysis are now being stored in computeried form.