Sensitivity and specificity of the Neuropad for distal sensory peripheral neuropathy (DSPN) in subjects with HIV-Infection: A case controlled observational study

Abstract

ObjectiveThe aim of the current study was to assess the diagnostic accuracy of the Neuropad for detecting distal sensory peripheral neuropathy (DSPN) related to human immunodeficiency virus (HIV)-infection. DesignSingle-gate observational case-control study. MethodsA convenience sample of 30 HIV-infected subjects with a mean age of 48.9 years (95% CI 45.6–52.3) and no other potential causes of neuropathy were recruited from the Ian Charleson Day Centre (London, UK). Sudomotor function was assessed with the Neuropad, an adhesive patch designed to measure sweat production, using a 10-min cut-off. Vibration perception threshold (VPT) testing with a neurothesiometer and the painDETECT questionnaire (PD-Q) were used as reference standard measures of DSPN. Results16 participants with sudomotor dysfunction and 14 with healthy sudomotor function were included in analysis. Compared to VPT (>25 V) the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the Neuropad yielded 66.7%, 48.1%, 12.5% and 92.9% respectively. For the PD-Q (>12) sensitivity of the Neuropad was 100% and specificity was 58.3%, with PPV and NPV of 37.5% and 100% respectively. ConclusionsThe Neuropad may be a suitable screening tool for HIV-related DSPN, and can reliably exclude healthy individuals in the clinical setting. Abnormal Neuropad results require referral to confirm diagnosis. Limitations exist in the sampling method and study size. The use of reference standard measures of small nerve fibre function and continuous Neuropad quantification would strengthen future research.