How well did a monofilament test detect diabetic polyneuropathy in referred patients?

Details

Simple, inexpensive diagnostic tools are needed for diabetic polyneuropathy (DPN). The researchers assessed the diagnostic accuracy of the 5.07/10 g monofilament test in patients referred for polyneuropathy assessment, and examined the influence of disease severity, age, sex and neuropathic pain (NP).

Five Norwegian university hospitals recruited patients with diabetes aged 18–70 who had been referred to neurological outpatient clinics for polyneuropathy assessment. The 5.07/10 g Semmes-Weinstein monofilament examination (SWME) was validated against the Toronto consensus for diagnosing diabetic neuropathies, and results were stratified by age, sex and NP. Disease severity was graded using a combined nerve conduction study (NCS) Z-score, and logistic regression was used to assess whether severity predicted diagnostic accuracy. The study included 506 patients.

Overall sensitivity was 0.60 (95% CI 0.55–0.66), and specificity was 0.82 (95% CI 0.75–0.87). Positive and negative predictive values were 0.86 (95% CI 0.81–0.90) and 0.52 (95% CI 0.46–0.58), respectively; positive and negative likelihood ratios were 3.28 (95% CI 2.37–4.53) and 0.49 (95% CI 0.42–0.57), respectively. The SWME was less sensitive in women (0.43), had lower specificity in patients with NP (0.56), and performed worse in patients aged 50 or older. NCS-based disease severity did not affect diagnostic accuracy (OR 1.15, 95% CI 0.95–1.40).

The researchers concluded that the SWME had poor diagnostic performance in this referred population and was particularly unsuited to women and patients with NP. Its accuracy was not influenced by NCS-based severity, indicating that it did not perform better at later stages of DPN. They did not recommend the 5.07/10 g monofilament for evaluating patients with diabetes referred for polyneuropathy assessment.