Validity and Reliability of the Persian (Farsi) Version of the DN4 (Douleur Neuropathique 4 Questions) Questionnaire for Differential Diagnosis of Neuropathic from Non-Neuropathic Pains

The aim of our study was translation and assessment of validity and reliability of the Persian version of DN4 questionnaire. The goal was to fill the gap caused by the absence of a validated instrument in Persian to facilitate discrimination of neuropathic pain. In this study, the adaptation and validation of the questionnaire was carried out in 4 steps, including translation, retranslation, semantic, and literal assessments, and a pilot study for practicability and potential perception difficulties of the final Persian version on 45 patient samples. The questionnaire validation performed on 175 patients, 112 (64%) females with the mean age of 52.53 (SD = 14.98) ranging from 22 to 87 years of age with neuropathic (N = 86) and non-neuropathic pain (NNP) (N = 89). Sensitivity, specificity, and Youden Index in cut-off point >= 4 were 90%, 95%, and 0.85, respectively, which are noteworthy findings among other validation studies. The Cronbach's alpha coefficient of the whole questionnaire was 0.852. Inter-rater agreement and test-retest reliability were significant intraclass coefficient (ICC = 0.957 and ICC = 0.918, respectively). The Persian version of DN4 questionnaire is a reliable, valid, feasible, and easily administered tool for precise discrimination neuropathic pain from NNP in Farsi. The characteristics of this test can assist practitioner to diagnose neuropathic pain accurately for both clinical and research purposes.