Comparison of neuropathy symptom score/neuropathy disability score and nerve conduction velocities in the diagnosis of diabetic peripheral neuropathy

Objective To evaluate the efficacy and clinical value of the neuropathy symptom score/neuropathy disability score (NSS/NDS) compared with nerve conduction velocities (NCV) in the diagnosis of diabetic peripheral neuropathy (DPN). Methods Observational study of 679 patients diagnosed with type 2 diabetes mellitus (404 males and 275 females, the average age was (59±11) years) was performed using the standard NSS/NDS and NCV criteria for the diagnosis of DPN. Taking NCV as the gold standard, we compared NCV against NSS/NDS using the following parameters: sensitivity, specificity, positive and negative predictive values, Youden index, Kappa value and correlation. Correlation analysis was done by using Spearman correlation and multivariate logistic regression. Results The sensitivity, specificity, positive and negative predictive values, Youden index, Kappa value and correlation of NSS/NDS compared with NCV was 68.0%, 77.2%, 86.5%, 53.5%, 71.0%, 45.2%, 0.405, 0.424, respectively. The abnormal rate of NCV of patients was more remarkable when NSS score ≥5 or NDS score ≥6 (77.8%-100%). NSS and NDS demonstrated an obvious positive association with NCV(r=0.292, 0.358, both P<0.01). The NCV values for each nerve showed a negative correlation with the severity of symptoms and signs. Logistic regression analysis showed that the risk factors of DPN were disease duration, age and urinary albumin-to-creatinine ratio when NSS/NDS were considered as the diagnostic criteria(odds rations(OR)=1.085, 1.051, 1.002, all P<0.01). A similar result was observed with NCV. Conclusions NSS/NDS demonstrates a positive association with NCV, especially when neurological symptoms and neurological signs became more serious. NSS/NDS analysis is a simple, rapid, cheap and powerful screening tool for the diagnosis of DPN. Key words: Diabetes mellitus, type 2; Diabetic neuropathies; Neuropathy symptom score/neuropathy disability score; Nerve conduction velocities