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

Abstract

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 AMPPOCD and CVPOCD for the 139 participants was 7.4±5.8μV and 45.7±11.2m/s and mean AMPNCS and CVNCS was 7.2 ±6.1μV and 43.3±8.3m/s. Mean difference of AMPPOCD−AMPNCS was 0.3±3.8μV and was 2.3±8.5m/s for CVPOCD−CVNCS. A AMPPOCD of 6μV had 80% sensitivity and 80% specificity for identifying abnormal AMPNCS, while a CVPOCD of 44m/s had 81% sensitivity and 82% specificity to identify abnormal CVNCS. Abnormality in AMPPOCD or CVPOCD 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.