Can A High-Low Ratio Help Prevent Amputation?

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This X-ray shows a transmetatarsal amputation. A recent study in the Journal of Foot and Ankle Surgery suggests the Hi-Lo Ratio may be a useful tool in preventing amputation. (Photo courtesy of Christine Salonga, DPM, and Peter Blume, DPM)
Can A High-Low Ratio Help Prevent Amputation?
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Author(s): 
By Brian McCurdy, Senior Editor

      As lower-extremity amputation rates continue to be a serious concern, DPMs continue to work to find effective prevention strategies. A recent study in the Journal of Foot and Ankle Surgery examines the efficacy of using a high to low amputation ratio to identify patients who may be at a greater risk for amputation.

      The study proposed and evaluated a high to low (Hi-Lo) amputation ratio as another quality measure to provide insight into high-risk foot surveillance that goes beyond foot screening. Researchers performed a secondary analysis on Medicare administrative data, which included 37,808 minor, foot-level amputations and 44,599 major amputations that were performed between 1996 and 1997. The study also calculated longitudinal trends in the Hi-Lo ratio with data from the Centers for Disease Control and Prevention (CDC) from 1992 to 2002. Researchers discovered that the adjusted mean Hi-Lo ratio was 1.35, while the lowest ratio was 0.56 and the highest was 3.43.

      Study authors note that United States facilities have previously relied only on foot screenings to prevent amputation and say this may explain why amputation rates have not declined significantly. To reduce the incidence of amputation, authors argue that practitioners should use “a straightforward measure that can be implemented at any center” and propose the Hi-Lo ratio, used by the Veterans Affairs system, as an effective measure.

What Are The Ratio’s Advantages?

      The Hi-Lo ratio has several advantages that could be helpful outside the VA system, according to study co-author Jeffrey Robbins, DPM. As far as primary prevention goes, he says a healthcare program that emphasizes prevention would detect patient conditions before they progress to a point where a proximal amputation would be needed. For secondary prevention, Dr. Robbins notes if an amputation does become necessary, surgeons should perform the most distal amputation to preserve joints and reduce the weight of a prosthetic. In regard to tertiary prevention, Dr. Robbins notes that not only would the most skilled surgeons be performing the procedure but they would do the best job of predicting healing and selecting the appropriate amputation level, which would reduce the need for a subsequent amputation.

      “Systems of care that coordinate primary, secondary and tertiary prevention have the best chance to preventing amputation,” says Dr. Robbins, the Director of Podiatry Service at the VA Central Office in Cleveland. “Work needs to be done in the private sector to establish the kinds of relationships that can lead to a high level of coordination for these most vulnerable patients.”

      The Hi-Lo ratio suggests a multidisciplinary construct that Dr. Robbins says might include: screening procedures during primary care with control of systemic factors; examination and surveillance by podiatrists; foot surgery timed to correct limb-threatening deformities and address the early signs of infection; referral to vascular surgery for ischemic conditions; smoking cessation; and rehabilitation and prosthetic fit to reduce additional trauma and improve functional outcomes.

      Study co-author David G. Armstrong, DPM, PhD, compares the Hi-Lo ratio to a cholesterol test. He says the ratio may detect if something is slightly amiss. However, a closer look might identify the high reading as related to HDL or good cholesterol. Similarly, with the Hi-Lo ratio, Dr. Armstrong says the ratio may be high because it is a tertiary center that is receiving difficult podiatric cases late in their treatment course. He says the ratio may highlight room for improvement.

      “(However), this is a valuable beginning to a meaningful conversation that can help us keep a few more legs on a few more bodies,” says Dr. Armstrong, a Professor of Surgery, Chair of Research and Associate Dean at the William M. Scholl College of Podiatric Medicine at Rosalind Franklin University of Medicine in Chicago.

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