The Diagnostic Sensitivity, Specificity and Reproducibility of the Clinical Physical Examination Signs in Patients of Diabetes Mellitus for Making Diagnosis of Peripheral Neuropathy

Abstract

Background : Diabetes mellitus is one of the most common chronic diseases. Prevalence of neuropathy in type 1 and type 2 diabetes is as high as 66% and 59% respectively. As underdiagnosis of neuropathy is common in clinical practice, we plan to identify the symptoms and signs which either alone or in combination have the best predictive value. The research question for the current study is that in patients with diabetes mellitus (type 1 and type 2) what is the diagnostic accuracy of physical signs in the diagnosis of peripheral neuropathy, as compared to the electro-diagnostic test (nerve conduction studies, NCS) as a reference standard and the reliability of these physical signs as a bedside examination tool. Methods : The study was conducted at Mahatma Gandhi Institute of Medical Sciences, Sevagram. For a period of two months (May - June 2009) we prospectively identified all consecutive patients of diabetes mellitus (type 1 and type 2) admitted to the medicine wards. The clinical signs were evaluated in each of the two lower limbs of all patients by two observers blinded to each other. And then patients underwent electrodiagnostic studies done by the trained technician and interpreted by a trained physician. Results : Absent ankle reflex was the most sensitive sign to detect neuropathy of any type. Impairment of vibration had the highest specificity. None of the physical signs alone had sufficiently high positive likelihood ratio to significantly increase the post-test probability of neuropathy with the sign being positive. Similarly none of the signs by itself had a low negative likelihood ratio to be able to rule out neuropathy. The interobserver reproducibility of the physical signs was moderate to poor. Impaired vibration test had a fair agreement between the two observers. Conclusions : Our study implies the annual foot examination of the diabetes irrespective of the duration of the diabetes. In clinical practice, however electrophysiological tests should not replace clinical examination because NCS has many pitfalls and the interpretation of the results should be done in the context of clinical data. doi:10.4021/jem101e