Reversal of Diabetic Peripheral Neuropathy and New Wound Incidence: The Role of MIRE

Advances in Skin & Wound Care, Jul/Aug 2004 by Powell, Mark W, Carnegie, Dale E, Burke, Thomas J

ABSTRACT

OBJECTIVE: To determine if improved foot sensitivity to the Semmes-Weinstein 10-g (5.07) monofilament, originally impaired because of diabetic peripheral neuropathy, might be associated with a reduced incidence of new diabetic foot wounds.

DESIGN: Retrospective cohort study using a health status questionnaire.

SUBJECTS: Sixty-eight individuals over age 64 with diabetes, diabetic peripheral neuropathy, and loss of protective sensation who had clinically demonstrable increases in foot sensation to the Semmes-Weinstein monofilament after treatment with monochromatic near infrared photo energy.

MAIN RESULTS: After reversal of diabetic peripheral neuropathy following treatment with monochromatic near infrared photo energy, only 1 of 68 patients developed a new diabetic foot wound, for an incidence of 1.5%. Comparatively, the incidence previously reported in the Medicare-aged population with diabetes was 7.3%.

CONCLUSIONS: Improved foot sensitivity to the Semmes-Weinstein monofilament in patients previously suffering from loss of protective sensation due to diabetic neuropathy appears to be associated with a lower incidence of new diabetic foot ulcers when compared with the expected incidence in the Medicare-aged population with diabetes.

CLINICAL RELEVANCE: Therapeutic interventions that effectively improve foot sensitivity that has been previously diminished due to diabetic peripheral neuropathy may substantially reduce the incidence of new foot wounds in the Medicare-aged population with diabetes.

ADV SKIN WOUND CARE 2004;17:295-6, 298-300.

Of the more than 18 million individuals in the United States who have diabetes, 15% are over age 65.1 Health care costs in this age-group are often borne by Medicare. The direct cost of diabetes was estimated at $78 billion in 1997,2 growing to $91 billion in 2002.3 Over 51% of that $91 billion was spent on patients older than age 65.3 Treatment for one of the complications of diabetes-lower extremity ulcers-cost Medicare $1.5 billion in 1995.1 By 2001, the cost for treatment of diabetic foot ulceration and associated amputations had climbed to an estimated $10.9 billion.4

Fifteen percent or more of people with diabetes sustain 1 or more foot wounds during their lifetime,5 and they are 15 times more likely to suffer a nontraumatic lower extremity amputation than people without diabetes.6 As a result, reduction in the incidence of foot wounds and nontraumatic amputations among people with diabetes is an objective of Healthy People 2010.

Diabetic peripheral neuropathy (DPN), or sensory nerve dysfunction, is typically determined in a clinical setting by diminished sensation to the Semmes-Weinstein 10-g (5.07) monofilament (SWM) or by diminished vibration perception threshold (VPT) in the foot. DPN is widely considered a significant risk factor for diabetic foot wounds.7 Patients with diabetes who show sensitivity to the SWM rarely develop these wounds.8 As the severity of DPN progresses toward loss of protective sensation (LOPS), including insensitivity to the SWM, so does the risk of foot ulceration.9

DPN has been documented in more than 80% of patients who have 1 or more diabetic foot ulcers10; it is also a factor in more than 80% of all nontraumatic, lower extremity amputations performed on patients with diabetes.11 DPN can be identified in the intact, contralateral limb in more than 97% of lower extremity amputees.12 Although abnormal sensory nerve function has been detected in the contralateral limb of diabetic amputees, it is not present in age-matched amputees without diabetes.'3

In a study examining the effectiveness of therapeutic shoes in preventing reulceration in patients with diabetes, Reiber et all4 reported that more than 93% of all foot wounds that developed during the study were found in patients who were insensitive to the SWM. The inability to detect the SWM and a VPT of 25 volts (V) or more-indicators of sensory nerve dysfunction-have been shown to have similar sensitivity15 and a high correlation to each another.15 They have also been found to be predictive of diabetic foot wounds.16 Young et al6 16 6 reported that in a group of patients with no prior foot ulcers, fewer than 4% of patients with a VPT less than 25 V developed a foot wound, compared with almost 19% of those with a VPT of 25V or more; this represents a five-fold increase in incidence. No recurrent ulcers were seen in the group with a VFF of less than 25V; however, 30 recurrent foot wounds were noted in patients with a VPT of 25V or more.

Several studies have discussed the incidence of diabetic foot wounds, with the most exhaustive examination by Harrington et al.1 They analyzed Medicare claims data from the 1995 and 1996 Standard Analytic Files (SAF) 5%, which is a scalable database containing the complete claims representative of 5% of the Medicare population. Based on the analysis, Harrington et al' determined that the incidence rate of wounds in patients over age 65 was 7.3%. Abbott ct al17 reported a 7.2% incidence rate over 1 year in a sample of 1035 patients with diabetes (average age 60; range 23 to 70). Pham et al18 found an incidence of 11.6% in a group of 248 high-risk patients with diabetes (age 58 � 12) who exhibited, among other risk factors, sensory nerve dysfunction based on both SWM and VI3T testing.