A Closer Look At The Research Behind MIRE Therapy
Questioning The Use Of The SWM
The main tool used to evaluate changes in sensory neuropathy in all three randomized, controlled trials was some form of the SWM. While many papers tout the SWM as good screening tool for neuropathy with loss of protective sensation, the inaccuracy and inconsistency of SWMs and changes in the instrument’s loading force over time make it a poor choice for clinical research.5-9 Yong, Booth and McGill described inaccuracy and variability of new SWM and changes in the loading force of instruments with repetitive use.10-12 The “pivotal” studies to evaluate MIRE therapy have relied on a flawed and usually inaccurate tool to test neuropathy. Vibration perception threshold (VPT) testing is a test that is recommended for use in longitudinal studies. Arnall’s paper was the only one that used VPT testing as part of the clinical evaluation of sensory neuropathy. Although no data was cited, there was not a significant change in VPT, according to Arnall. Leonard reported “statistically significant” improvement in sensory neuropathy in limbs that received MIRE therapy.7 However, even if the statistical analysis the researchers used in the study was correct, the statistically significant results do not seem like they are clinically meaningful. For instance, at the end of Leonard’s study, in the MIRE treatment group, researchers accurately identified an average 2.4 sites out of five sites tested with the SWM.7 Clinically, “loss of protective sensation” is often defined as one or two sites missed with the 10 g monofilament.10 Accordingly, the level of improvement still leaves the patient with “loss of protective sensation.” The authors did not report the proportion of patients who changed from having a “high-risk foot” to having a normal level of sensation. That type of information would be more meaningful to most clinicians. Arnall, on the other hand, reports that patients in both treatment arms had an improvement in peripheral sensation so the average SWM values were <10 g of force.8 Could MIRE have a systemic effect? All three randomized clinical trials randomized limbs as opposed to randomizing patients. This design could allow for a systemic effect so both extremities could have benefited from therapy which was provided to one limb. This might explain the large and unexpected placebo effect that occurred in all three clinical studies.
Monochromatic infrared light energy therapy is a multimillion-dollar industry. If this is a therapy that really works, we need to provide it aggressively for all of our patients with diabetes who are “at risk” for foot ulceration. However, if the therapy does not work, we need to make sure healthcare resources are not wasted. We are the gatekeepers in many respects and prescribing expensive therapy that is ineffective or, at best, unproven is not a benefit to the patient or our profession. At first glance, the literature appears to support the use of MIRE to improve peripheral neuropathy among patients with diabetes. However, there are a number of concerns about the existing science. The quality of the clinical data is suspect and the ability of therapy to “reverse neuropathy” and prevent foot complications (such as ulceration, infection and amputation) related to sensory neuropathy is unproven. Further research needs to address design and analysis concerns. Dr. Lavery (shown at the right) is a Professor in the Department of Surgery at Texas A&M Health Science Center College of Medicine. Dr. Steinberg (shown at the left) is an Assistant Professor in the Department of Plastic Surgery at the Georgetown University School of Medicine in Washington, D.C. Editor’s note: For further reading, see “Current And Emerging Options For Treating Diabetic Neuropathy” in the March 2005 issue of Podiatry Today.