Cultural translation and psychometric testing.
To translate and validate the Iranian versions of the Neck Disability Index (NDI-IR) and the Neck Pain and Disability Scale (NPDS-IR).
The widely used the NDI and the NPDS scales have not been translated and validated for Persian-speaking patients with neck pain. This was to provide a validated instrument to measure functional status in patients with neck pain in Iran.
The translation and cultural adaptation of the original questionnaires were carried out in accordance with the published guidelines. One hundred and eighty-five patients with neck pain were participated in the study. Patients were asked to complete a questionnaire booklet including the NDI-IR, the NPDS-IR, the Iranian SF-36, and a visual analog scale (VAS) of pain. To carry out the test-retest reliability, 30 randomly selected patients with neck pain were asked to complete the questionnaire booklet 48 hours later for the second time.
Cronbach α coefficient for the NDI-IR was 0.88 and for the 4 subscales of the NPDS-IR was found to be satisfactory (ranging from 0.74 to 0.94). The NDI-IR and the NPDS-IR subscales showed excellent test-retest reliability (intraclass correlation coefficient ranged from 0.90 to 0.97; P < 0.01). The correlation between the NDI-IR and the NPDS-IR subscales and functional scales of the SF-36 showed desirable results, indicating a good convergent validity (Pearson correlation coefficients ranged from −0.31 to −0.70). The correlation between the NDI-IR and the VAS was 0.71 and between the NPDS-IR subscales and the VAS ranged from 0.63 to 0.79 (P < 0.01).
The Iranian versions of the NDI and NPDS are reliable and valid instruments to measure functional status in Persian-speaking patients with neck pain in Iran. They are simple and easy to use and now can be applied in clinical settings and future outcome studies in Iran and other Persian speaking communities.
There is no validated instrument to measure functional status in Persian-speaking patients with neck pain in Iran. The present study was performed to culturally translate the Neck Disability Index and Neck Pain and Disability Scale into Persian, and then to investigate the psychometric properties of the Iranian versions produced.
From the *Department of Physical Therapy, Faculty of Rehabilitation Sciences, Medical Sciences/University of Tehran, Tehran, Iran; †Faculty of Mechanical Engineering, Sharif University of Technology, Tehran, Iran. ‡Iranian Institute for Health Sciences Research, Tehran, Iran; §Centre for Spinal Studies and Surgery, University Hospital, Nottingham, UK; ¶Department of Physical Therapy, Faculty of Rehabilitation Sciences, Isfahan University of Medical Sciences, Isfahan, Iran; ∥Physical Therapy Clinic, Milad Hospital, Tehran, Iran; **Faculty of Paramedical Sciences, Zahedan University of Medical Sciences, Zahedan, Iran; and ††Department of Orthopedic Surgery, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.
Acknowledgment date: May 3, 2007. First revision date: July 23, 2007. Second revision date: August 6, 2007. Acceptance date: August 6, 2007.
The manuscript submitted does not contain information about medical device(s)/drug(s).
Institutional funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.
Address correspondence reprint requests to Sayed Javad Mousavi, MSc, Department of Physical Therapy, Faculty of Rehabilitation Sciences, Medical Sciences/University of Tehran, Pich-e-Shemiran, Enghelab Ave., Tehran, Iran 11489-65141; E-mail: email@example.com