Accuracy of the Neuropad Test for the Diagnosis of Distal Symmetric Polyneuropathy in Type 2 Diabetes

OBJECTIVE: To estimate the accuracy of Neuropad for the diagnosis and staging of distal symmetric polyneuropathy (DPN) across different stages of neuropathy, using multiple-level likelihood ratios (LRs) to interpret the time necessary to complete the color change of the test. RESEARCH DESIGN AND METHODS: We conducted a cross-sectional, cohort-type diagnostic accuracy study in 251 consecutive adult type 2 diabetic patients with no peripheral arterial disease or other potential causes of neuropathy, who were recruited between January 2005 and December 2008 from the diabetes outpatient clinics in Alexandroupolis Hospital, Greece. Patients were tested for DPN by means of the neuropathy disability score (NDS) and Neuropad. Multiple-level LRs for time to complete color change were calculated across different stages of neuropathy. RESULTS: The areas under the curve for the diagnosis of any (NDS of ≥3), at least moderate (NDS of ≥6), or severe (NDS of ≥9) DPN were 0.91, 0.96, and 0.97, respectively. The calculation of multiple-level LRs showed that time to complete color change <360 s suggested the absence of neuropathy. Values between 360 and 1,000 s were indicative of mild neuropathy. Finally, values between 1,000 and 1,200 or >1,200 s were strongly suggestive of moderate or severe DPN, respectively. CONCLUSIONS: Neuropad could be used as a triage test for the diagnosis and staging of DPN in patients with type 2 diabetes, prompting referral to specialized care setting.