The Validity and Reliability of a New Modified Persian Version of DN4 to Discriminate Non-neuropathic from Neuropathic

Abstract

Introduction: One of the popular questionnaires for screening neuropathic pain is the DN4 (Douleur Neuropathique 4) which has been translated into many languages and validated in different populations. So, we wanted to determine the Persian version of this questionnaire’s reliability and validity to differentiate neuropathic pain from other painful non-neuropathic conditions. Methods: This cross-sectional study was conducted on 120 patients who suffered from chronic pain referred to the Physical Medicine and Rehabilitation Department at the three great referral hospitals in Tehran, Iran in 2016. In this study, a modified version of DN4 was used to validate adding a question related to the appearance of pain in an especial joint and adding visual analogue scaling (VAS) score in each item. Results: The modified DN4 questionnaire had high reliability for assessing neuropathic pain with the Cronbach’s alpha coefficient of 0.874. The correlation coefficients obtained by the retest intra-class correlation test ranged from 0.650 to 0.941. Also, the internal consistency of Spearman’s R coefficients ranged from 0.482 to 0.904. Test-retest reliability analysis also showed a higher intraclass correlation (ICC) value in the neuropathic than non-neuropathic pain group (0.85 vs0.73). The modified DN4 questionnaire could effectively discriminate neuropathic pain from non-neuropathic pain with the area under the curve (ROC) of 0.989 (95% CI: 971–1000, P < 0.001). The best cutoff value for the modified DN4 questionnaire to diagnose neuropathic pain was 5, yielding a sensitivity of 98.3% and a specificity of 90.3%. Conclusion: Applying the new modified Persian version of DN4 achieved by adding a VAS score and a new question related to the appearance of pain in an especial joint led to high reliability and validity for this tool to discriminate neuropathic from non-neuropathic pain.