Cross-cultural adaptation, validity, and reliability of the Neck OutcOme Score (NOOS-Ar) among the Saudi Arabian populace

Abstract

BACKGROUND: To date the Neck OutcOme Score (NOOS) was not cross-culturally adapted, validated or available in the Arabic language, although it was available in other languages. OBJECTIVE: To translate and cross-culturally adapt the Arabic version of the Neck OutcOme Score (NOOS-Ar) and study its psychometric properties. METHODS: A sample of 146 subjects with chronic neck pain filled in the NOOS-Ar questionnaire to determine the Cronbach’s alpha (α) for internal consistency, test-retest reliability by intraclass correlation coefficients(2,1) [ICC(2,1)], inter-item correlation, measurement error by coefficient of variance and minimal detectable change, ceiling and floor effects, convergent construct validity with visual analog scale (VAS) by Spearman’s rank correlation coefficient (ρ) and factor analysis to calculate and determine its psychometric properties. RESULTS: Excellent internal consistency (Cronbach’s α> 0.9) and test-retest reliability [ICC(2,1)> 0.9] were observed in NOOS-Ar. None of the five subscales of the NOOS-Ar showed a floor or ceiling effect. The coefficient of variance was generally high, but the minimal detectable change was within the acceptable range (< 30%). The ‘everyday activity and pain’ and ‘symptoms’ subscales of the NOOS-Ar, showed a moderate correlation with VAS. CONCLUSION: The NOOS-Ar is highly reliable and has a moderate to good degree of convergent construct validity with VAS with no floor or ceiling effects.