Sensitivity and specificity of a new indicator test (Neuropad) for the diagnosis of peripheral neuropathy in type 2 diabetes patients: a comparison with clinical examination and nerve conduction study.

OBJECTIVE: The objective of this study was to evaluate the sensitivity and specificity of a new indicator test (Neuropad) for the diagnosis of peripheral neuropathy in type 2 diabetes patients as compared with clinical examination and nerve conduction study (NCS). PATIENTS AND METHODS: This study included 120 type 2 diabetes patients (58 men) with a mean age of 67.3 +/- 5.9 years and a mean diabetes duration of 13.1 +/- 3.2 years. Diabetic neuropathy was diagnosed through the Neuropathy Disability Score. An NCS was performed on radial, ulnar, sural, and common and deep peroneal nerves. Patients were also examined with the new indicator test. The "time to complete color change of the test" from blue to pink was recorded. The test was considered abnormal in patients who exhibited a time to complete color change of the test exceeding 600 s in at least one foot.
RESULTS: Neuropathy was diagnosed by clinical examination in 83 (69.2%) patients. The sensitivity of the indicator test for clinical neuropathy was 95.2%, and its specificity was 67.6%. The sensitivity of NCS for clinical neuropathy was 94%, and its specificity was 62.1%. The sensitivity of the indicator test for abnormal NCS was 97.8%, and its specificity was 96.4%.
CONCLUSIONS: The new indicator test has a very high sensitivity not only for the diagnosis of clinical neuropathy but also for the diagnosis of neurophysiological neuropathy. Specificity is moderately high for the diagnosis of clinical neuropathy, while it is particularly high for the diagnosis of neurophysiological neuropathy. The indicator test has a validity comparable to that of NCS for the diagnosis of diabetic neuropathy. Finally, the time to complete color change of the test is associated with the severity of nerve conduction impairment.