Indian Journal of Physiotherapy and Occupational Therapy - An International Journal

Cultural translation and psychometric testing

To translate and test the psychometric properties of Gujarati versions of the NPAD questionnaire

Although commonly used, no previous reports exist in the translation process or the testing of the psychometric properties of the Gujarati version of the NPAD used in India.

Translation and cross-cultural adaptation of the original English version of the NPAD was performed according to published guidelines. A panel of 24 healthcare professionals completed the content validity form. A total of 150 patients with chronic neck pain participated in the study and were asked to complete the Neck Disability Index-Gujarati version (NDI-G), Neck Pain Disability Scale-Gujarati version (NPAD-G), Patient Health Questionnaire-9 (PHQ-9) and a visual analog scale(VAS-P, VAS-Fd, & VAS-Hd; 0–5). Psychometric evaluation included factor analysis, internal consistency, test-retest reliability, agreement, and construct validity. Test-retest reliability for the NPAD-G was examined in 30 patients. Patients completed the questionnaires twice with an interval of 48 hours.

Factor analysis revealed a three-factor solution for the NPAD-G. Cronbach's α value for the NPAD-G was excellent 0.936. The three NPAD-G subscales ranged from 0.733 to 0.880. Good to excellent test-retest reliability was demonstrated for all measurements (Intra-class Correlation Coefficient range= 0.74–0.91, P < 0.001). NPAD-G was moderately correlated with the VAS-P, VAS-Fd, VAS-Hd (r = 0.559, 0.686, 0.681 respectively P < 0.001). NPAD-G scores were moderately correlated with PHQ-9 scores (r= 0.642). The minimal detectable change was 25.24 points for NPAD-G (scale range = 0–100).

The NPAD-G seems to be reliable instruments to measure functional limitation and disability in Gujarati patients with neck pain. However, further research is still needed to determine responsiveness of this questionnaire.