Cross-cultural adaptation of the Neck Pain and Disability Scale: a methodological systematic review.

BACKGROUND: Neck pain is a common and uncomfortable symptom, adversely affecting the work and life of those affected. The Neck Pain and Disability Scale (NPDS) is widely used in neck pain assessment. It has been cross-culturally adapted into several languages to extend its reach to non-English-speaking countries. The aim of this study was to comprehensively evaluate the translation procedures and measurement properties of cross-cultural adaptations of the NPDS.

METHOD: We searched multiple databases, including PubMed, Embase, CINAHL, SciELO, PsycINFO, Medline, SinoMed, PsycINFO, Web of Science, and Scopus, using the keywords "Neck Pain and Disability Scale," "NPDS," "cross-cultural," and "translation". Cross-cultural adaptation and quality control of measurement properties of adaptation procedures were independently conducted by two reviewers in accordance with Guidelines for the Process of Cross-Cultural Adaptation of Self-Report Measures and Quality Criteria for Psychometric Properties of Health Status Questionnaire.

RESULTS: There are 15 adaptations of NPDS in 11 different languages with multiple versions in Korean, simplified Chinese and Turkish with 19 studies. In about half of these studies, forward and back translations were conducted. Specially, they mostly focus on the synthesis phase of the translations. Only the simplified-Chinese-2011 adaptation meets the standards of composition due to the existence of an expert committee. Internal consistency, reliability, and construct validity have been evaluated in most existing eligible articles. Half of these articles tested ceiling and floor effects, and only a few included agreement responsiveness and interpretability.

CONCLUSION: The Italian (publication 1 and 2), Persian-Iranian, simplified-Chinese-2011, and Thai adaptations show better quality than others with regard to cross-cultural adaptation and measurement properties. Further studies should fully assess the measurement properties of the NPDS in the Dutch (publication 1 and 2), Hindi-Indian, Korean-2013, simplified-Chinese-2010, Turkish-2004, and Turkish-2007 adaptations.