Validity of a point-of-care nerve conduction device for polyneuropathy identification in older adults with diabetes: Results from the Canadian Study of Longevity in Type 1 Diabetes

OBJECTIVE: Point-of-care nerve conduction devices (POCD) have been studied in younger patients and may facilitate screening for polyneuropathy in non-specialized clinical settings. However, performance may be impaired with advanced age owing to age-related changes in nerve conduction. We aimed to evaluate the validity of a POCD as a proxy for standard nerve conduction studies (NCS) in older adults with type 1 diabetes (T1D). METHODS: Sural nerve amplitude potential (AMP) and sural nerve conduction velocity (CV) was measured in 68 participants with ≥ 50 years T1D duration and 71 controls (from age/sex-matched subgroups) using POCD and NCS protocols. Agreement was determined by the Bland-Altman method, and validity was determined by receiver operating characteristic curves. RESULTS: T1D were 53% female, aged 66±8yr and had diabetes duration 54yr[52,58]. Controls were 56%(p = 0.69) female and aged 65±8yr(p = 0.36). Mean AMP(POCD) and CV(POCD) for the 139 participants was 7.4±5.8μV and 45.7±11.2m/s and mean AMP(NCS) and CV(NCS) was 7.2±6.1μV and 43.3±8.3m/s. Mean difference of AMP(POCD)−AMP(NCS) was 0.3±3.8μV and was 2.3±8.5m/s for CV(POCD)−CV(NCS). A AMP(POCD) of ≤6μV had 80% sensitivity and 80% specificity for identifying abnormal AMP(NCS), while a CV(POCD) of ≤44m/s had 81% sensitivity and 82% specificity to identify abnormal CV(NCS). Abnormality in AMP(POCD) or CV(POCD) was associated with 87% sensitivity, while abnormality in both measures was associated with 97% specificity for polyneuropathy identification. CONCLUSIONS: The POCD has strong agreement and diagnostic accuracy for identification of polyneuropathy in a high-risk subgroup and thus may represent a sufficiently accurate and rapid test for routinely detecting those with electrophysiological dysfunction.