Introduction: Musculoskeletal disorders are among the top 10 injuries accounting for absence from work. The Extended Nordic Musculoskeletal Questionnaire (NMQ-E) is one of the many tools used to examine these disorders. The present study was conducted to translate and localize the NMQ-E and to evaluate the face validity and test-retest reliability of its Persian version.

Materials and Methods: The present non-empirical methodological study used the International Quality Of Life Assessment (IQOLA) approach to translate the NMQ-E into Persian. The face validity of the Persian version was examined in a sample of 15 patients with musculoskeletal disorders (MSDs) and its absolute and relative test-retest reliability were examined in a sample of 48 patients using the Standard Error of Measurement (SEM) and the Intra-class Correlation Coefficient (ICC). The Kappa coefficient was also used to measure the inter-rater agreement for nominal variables.

Results: The translation and localization of the NMQ-E was deemed easy and acceptable. All the items of the questionnaire had an acceptable face validity. The Intra-class Correlation Coefficient and the Standard Error of Measurement of the Persian version of the NMQ-E were deemed acceptable (SEM=0.56-1.76 and ICC>0.7) and the Kappa coefficient was calculated as 0.78-1.00. 

Conclusion: The Persian version of the Extended Nordic Musculoskeletal Questionnaire showed an acceptable validity and test-retest reliability for assessing musculoskeletal disorders in Iranian patients.