Screening for diabetic foot neuropathy and ulcers would prevent amputations and reduce health care costs. Intensive foot care, including patient education, appropriate shoes and attendance at foot clinics, might help prevent some amputations, but a means to identify patients at risk of developing foot ulcers would be useful as well. Smieja and colleagues reporting for the International Cooperative Group for Clinical Examination Research compared monofilament examination of the diabetic foot with conventional assessment methods to assess reproducibility and accuracy of each type of examination.
Adult patients attending one of 10 outpatient diabetes clinics in the United States, Canada and Switzerland were eligible for the cross-sectional study unless they were cognitively impaired, had a history of stroke or had any active foot infection or ulcer. Type and duration of diabetes and history of foot complications were recorded. Patients were asked to identify any recent sensation in the feet, such as numbness, burning or “pins and needles.” Pinprick sensation, position sense, vibration sensation and ankle reflexes were assessed in both feet. A second examiner then assessed for monofilament sensation with a Semmes-Weinstein 5.07 monofilament at 10 sites per foot. The monofilament was applied until it buckled, and then it was held on the foot for 1 second. Patients were asked to state the time interval during which the monofilament was felt or say if they could not tell. Abnormal monofilament examination was defined as incorrect identification of the stimulus at any of eight sites on the plantar aspect of either foot.
A total of 304 patients were included in the study, and more than one half had no sensation on at least one site during the monofilament examination. Reproducibility was moderate for the monofilament examination and fair for the traditional examination. Of interest, patient perceptions of abnormal foot sensation, such as burning or numbness, were not sensitive (65 percent) or specific (62 percent) for detecting an abnormal monofilament examination. The conventional examination that was most specific for an abnormal monofilament examination was abnormal position sense (98 percent), but a normal position sense was not sensitive (20 percent). Assessment of specific monofilament sites revealed that use of four points per foot (third and fifth toes and first and third metatarsal heads) yielded as much, and as accurate, information as using eight or more sites.
The authors conclude that use of the Semmes-Weinstein monofilament is a reproducible and practical means of identifying patients who may be at higher risk for neuropathy or foot ulcers associated with diabetes. Therefore, screening diabetic patients for foot problems with the monofilament test is recommended over other conventional neurologic tests.