Cross-cultural adaptation and validation of the Northwick park neck pain questionnaire to Urdu language

BACKGROUND: Despite its widespread use for assessing pain and disability in patients suffering from neck pain, the Northwick Park Neck Pain Questionnaire (NPQ) has yet to be translated and validated in Urdu. The purpose of the present study was to translate and cross-culturally adapt the NPQ into Urdu language (NPQ-U), and to investigate the NPQ-U’s psychometric properties in patients with non-specific neck pain (NSNP). METHODS: The NPQ was translated and cross-culturally adapted into Urdu in accordance with the previously described guidelines. The study included 150 NSNP patients and 50 healthy participants. The NPQ-U, Urdu version of neck disability index (NDI-U), neck pain and disability scale (NPDS), and numerical pain rating scale (NPRS) were completed by all participants on first visit. After three weeks of physical therapy, the patients completed all of the questionnaires listed above, along with the global rating of change scale. Test-retest reliability was determined on 46 randomly selected patients who completed the NPQ-U again two days after the first response. The NPQ-U was evaluated for internal consistency, content validity, construct (convergent and discriminative) validity, factor analysis, and responsiveness. RESULTS: The NPQ-U demonstrated excellent test-retest reliability (intra-class correlation coefficient = 0.96) and high internal consistency (Cronbach’s alpha = 0.89). There were no floor or ceiling effects for the NPQ-U total score, indicating good content validity. A single factor was extracted, which explained 54.56% of the total variance. For convergent validity, the NPQ-U showed a strong correlation with NDI-U (r = 0.89, P < 0.001), NPDS (r = 0.71, P < 0.001), and NPRS (r = 0.73, P < 0.001). The results revealed a significant difference between patients and healthy controls in the NPQ-U total scores (P < 0.001) demonstrating significant discriminative validity. A significant difference in the NPQ-U change scores between the stable and the improved groups (P < 0.001) confirmed its responsiveness. Furthermore, the NPQ-U change score showed a moderate correlation with NPDS change score (r = 0.60, P < 0.001) and NPRS change score (r = 0.68, P < 0.001), but a strong correlation with NDI-U change score (r = 0.75, P < 0.001). CONCLUSION: The NPQ-U is a reliable, valid, and responsive tool for assessing neck pain and disability in Urdu-speaking patients with NSNP.