Psychometric Properties of the Persian Version of the ID-Pain Questionnaire

The Identification Pain questionnaire (IDPQ) is one of the recommended tools by the Neuropathic Pain Special Interest Group of the International Association for the Study of Pain for neuropathic pain screening. This study aimed to translate, cross-culturally adapt, and validate the Persian version of the IDPQ.

First, the IDPQ was translated based on the recommended guidelines. Afterward, the internal consistency (Cronbach's alpha coefficient), test-retest reliability (intraclass correlation coefficient), construct validity (compared to the Douleur Neuropathique 4 [DN4] questionnaire), and discriminant validity (Receiver operating curve analysis) of the IDPQ-P were evaluated. A total of 90 patients with neuropathic (n=50) and nociceptive pain (n=40) were enrolled in the study. In the next 72 h after the initial assessment, 30 patients (15 with neuropathic and 15 with nociceptive pain) completed the IDPQ-P.

No modifications were needed in the process of translation and cultural adaptation. Cronbach's alpha coefficient was obtained at 0.47 for all patients, indicating poor internal consistency. The intraclass correlation coefficient was estimated at 0.97, showing excellent test-retest reliability. A high correlation was found between the DN4 questionnaire and IDPQ-P (0.74), showing acceptable construct validity. The area under the curve was 0.94 (95% CI: 0.88-0.99) and 0.92 (95% CI: 0.85-0.99) when the physician's diagnosis and the DN4 cut-off value were used as the reference standard, respectively. The optimal cut-off value of ≥ 2 demonstrated the highest sensitivity (98%) and specificity (79%).

The IDPQ-P can be used in the clinical setting as an accurate and quick screening tool to diagnose patients with neuropathic pain. Sufficient test-retest reliability, construct validity, discriminant validity, and high diagnostic accuracy were found for the IDPQ-P.