The Semmes-Weinstein monofilament as a potential predictor of foot ulceration in patients with noninsulin-dependent diabetes

The objective was to evaluate the Semmes-Weinstein monofilament as a potential predictor of foot ulceration. A case-control study was carried out in a teaching hospital clinic specializing in diabetes and hyperlipidemic disorders. Two groups of patients with noninsulin-dependent diabetes mellitus were studied: 168 with no history of foot lesions (No-Ulcer group, aged 58.1 ± 9.7 years, duration 11.5 ± 7.8 years) and 14 who had at least one foot ulceration during the last year (foot ulcer group, aged 60.8 ± 7.8 years', duration 17.1 ± 10.5 years). The authors defined and measured a 'monofilament index' using a size 5.07 Semmes-Weinstein monofilament on three locations on each foot and then measured peroneal nerve current perception thresholds using the Neurometer® at three frequencies: 5 Hz, 250 Hz, and 2,000 Hz. The monofilament index score was lower in patients in the foot ulcer group than in patients in the No-Ulcer group (1.71 ± 2.36 vs 5.21 ± 1.81, P < 0.001). A cutoff point at an index of 5 out of 6 yielded a sensitivity rate of 85.71% and a false-positive rate of 16.07%. The peroneal nerve current perception threshold was higher (P < 0.005) in patients in the foot ulcer group than in patients in the No-Ulcer group for all frequencies (605.8 ± 414.6 vs 181.5 ± 272.3 for 5 Hz; 743.2 ± 361.7 vs 251.6 ± 283.7 for 250 Hz; 859.4 ± 220.2 vs 423.3 ± 252.6 for 2,000 Hz). For the Neurometer®, the best combination of sensitivity rate (92.9%) and false- positive rate (26.2%) was attained at a frequency of 2,000 Hz, with a cutoff point at 450 (4.5 mA). The authors conclude that the monofilament index using the 5.07 Semmes-Weinstein monofilament is inexpensive and a promising potential predictor for foot ulceration in patients with noninsulin-dependent diabetes mellitus.