Validation of the Simplified Chinese Version of the Functional Rating Index for Patients With Nonspecific Neck Pain in Mainland China

Study Design. Validation of a self-report questionnaire, Functional Rating Index (FRI). Objective. To evaluate the psychometric properties of the simplified Chinese (SC) version of FRI in patients with nonspecific neck pain (NP). Summary of Background Data. FRI has been cross-culturally validated in few languages with excellent reliability, validity, and clinical utility when it is applied in patients with low back pain. Recently, it has been pointed out that FRI can be employed to assess patients with NP. However, FRI has not been validated in patients with NP in China. Methods. The cross-culturally adapted 10-item SC-FRI was completed by 122 patients with nonspecific NP, along with the Neck Disability Index, Neck Pain and Disability Scale, 36-Item Short Form Health Survey, and Pain Visual Analogue Scale. Psychometric evaluation included score distribution, internal consistency, test-retest reliability, and construct validity. Results. SC-FRI attained a high completion rate (96.9%). Each item was scored with a normal distribution without any floor and ceiling effects. The internal consistency and test-retest reliability were good to excellent (Cronbach alpha coefficient = 0.86; intraclass r = 0.97). Construct validity was confirmed by a strong correlation with Neck Disability Index, Neck Pain and Disability Scale, and Visual Analogue Scale (r = 0.77, 0.78, and 0.86, respectively, all P < 0.0001), and with the physical functioning and bodily pain domains (r = -0.69 and -0.66, respectively, both P < 0.0001), and by a weak correlation with the vitality, role-emotional, and mental health domains of 36-Item Short Form Health Survey. Conclusion. SC-FRI showed satisfactory clinical utility, internal consistency, test-retest reliability, and construct validity in Chinese-speaking patients with nonspecific NP.