Validation of DN4 as a screening tool for neuropathic pain in painful diabetic polyneuropathy.

Aims DN4(DouleurNeuropathique en 4Questions) is a screening tool for neuropathic pain consisting of interviewquestions (DN4-interview) and physical tests. It has not formally been validated in diabetes. We evaluated the validity and diagnostic accuracy of DN4 and DN4-interview in identifying neuropathic pain of painful diabetic polyneuropathy. Methods In 158 patients with diabetes, the presence of diabetic polyneuropathy and neuropathic pain was assessed using scoring system for symptoms and signs, quantitative sensory testing, nerve conduction studies, pain history, numerical rating scale, and Short-Form McGill Pain Questionnaire. Painful diabetic polyneuropathy was defined as the presence of diabetic polyneuropathy plus chronic neuropathic pain in the same area as neuropathic deficits. Ablinded investigator performed DN4. Results The DN4 score was significantly related to all the neurological and electrophysiological measurements and to Short- FormMcGill Pain Questionnaire (q = 0.58, P < 0.0001). DN4 and DN4-interview scores showed a high diagnostic accuracy for painful diabetic polyneuropathy with areas under the receiver operating characteristic curve of 0.94 and 0.93, respectively. At the cut-off of 4, DN4 displayed sensitivity of 80%, specificity of 92%, positive predictive value (PPV) of 82%, negative predictive value (NPV) of 91%, and likelihood ratio for a positive result (LR+)of 9.6.At the cut-offof 3,DN4-interviewshowed sensitivity and specificity of 84%, PPV of 71%, NPV of 92%, and LR+ of 5.3. Conclusions This is thefirst validation study ofDN4for painful diabetic polyneuropathy, which supports itsusefulness as both a screening tool for neuropathic pain in diabetes and a reliable component of the diagnostic work up for painful diabetic polyneuropathy.