Validity of the Diabetic Neuropathy score and Diabetic Neuropathy Examination score as screening tools for the detection of distal symmetrical diabetic neuropathy

Abstract

Sri Lanka is a developing country in which one of five adults has either diabetes or prediabetes. Complications of diabetes, especially diabetic neuropathy, place a considerable burden on the country’s health care system and so there is a dire need for an easy to perform, cheap, and validated tool for the early detection of diabetic neuropathy among Sri Lankan patients. Many validated scoring systems are available in Western countries for the screening of distal symmetrical diabetic neuropathy (DSPN), which accounts for 75% of all diabetic neuropathies, with the two most common being the Diabetic Neuropathy Symptom (DNS) and Diabetic Neuropathy Examination (DNE) scores. The DNS score incorporates information from four questions related to medical history. The maximum score is 4 points, with scores >1 considered abnormal. The DNE score is based on a hierarchical physical examination consisting of eight items. The maximum score is 16 and scores >3 are considered abnormal. However, we were unable to find a similar screening tool validated for the local Sri Lankan population. Thus, we undertook the present study to examine the clinical utility of the commonly used DNS and DNE scores for diagnosing diabetic neuropathy among our local population of diabetics. Patients with diabetes attending medical clinics in the Teaching Hospital (Galle, Sri Lanka) were recruited to the study, which was approved by the Ethical Review Committee, Faculty of Medicine (University of Ruhuna, Galle). All participants provided informed consent. Demographic and disease-related data were collected using a pretest questionnaire. The DNS and DNE scores were obtained separately by two researchers who were blinded to the score obtained using the other tool. Both DNS and DNE scores were obtained as per the recommended guidelines. The Semmes– Weinstein monofilament (SW-MF) and vibration perception threshold (VPT) determined using a biothesiometer were considered as reference standards for the detection of diabetic neuropathy. Both these tests were performed on the same as the DNS and DNE questionnaires by another medical officer who did not know the results of the DNS and DNE scores. The SW-MF test was applied with 10 g pressure and standard ‘‘yes ⁄no’’ responses. It was applied to five sites on each foot: plantar surface of the first toe, the plantar surfaces of the first, third, and fifth metatarsal heads, and the plantar surface of the heal. The VPT was performed using a hand-held biothesiometer (Madras Engineering Services, Chennai, India). The VPT was determined over the dorsal aspect of the hallux on the interphalangeal joint. The voltage of the vibration was increased from 0 to 50 V until the patient perceived a vibration. The mean of three measurements was used as the value for each patient as was compared against ageadjusted reference values. Values higher than the mean + 2 SD were considered abnormal. In all, 314 diabetic patients (98 men) were screened. The mean (±SD) age and duration of the disease were 62.0 ± 10.5 and 9.4 ± 5.3 years, respectively. The prevalence of neuropathy in the study population determined by the SW-MF and VPT tests was 49.5% and 89.6%, respectively. The sensitivity and specificity of the DNS and DNE scores in determining DSPN are given in Table 1. Correspondence P.L. Gayani C. Liyanage, Departments of Pharmacology and Medicine, Faculty of Medicine, University of Ruhuna, PO Box 70, Galle, Sri Lanka. Tel: +94 77 3 548684 Fax: +94 2 222314 Email: gayanicl@yahoo.com Received 9 December 2011; revised 28 March 2012; accepted 10 April 2012. doi: 10.1111/j.1753-0407.2012.00201.x Journal of Diabetes 4 (2012) 264–265