Simplified Chinese version of the core outcome measures index (COMI) for patients with neck pain: cross-cultural adaptation and validation

Purpose The aim of this study was to translate and cross-culturally adapt the Core Outcome Measures Index for (COMI) into a Simplified Chinese version (COMI-SC) and to evaluate the reliability and validity of COMI-SC in patients with neck pain.Methods The COMI-neck was translated into Chinese according to established methods. The COMI-neck questionnaire was then completed by 122 patients with a hospital diagnosis of neck pain. Reliability was assessed by calculating Cronbach's alpha and intraclass correlation coefficient (ICC). Construct validity was assessed by correlating the COMI-neck with the Neck Pain and Disability Scale (NPDS), the Neck Disability Index (NDI), the VAS and the Short Form (36) Health Survey (SF-36). Using confirmatory factor analysis to validate the structural, convergent and discriminant validity of the questionnaire.Results The COMI-neck total scores were well distributed, with no floor or ceiling effects. Internal consistency was excellent (Cronbach's alpha = 0.861). Moderate to substantial correlations were found between COMI-neck and NPDS (r = 0.420/0.416/0.437, P < 0.001), NDI (r = 0.890, P < 0.001), VAS (r = 0.845, P < 0.001), as well as physical function (r = - 0.989, P < 0.001), physical role (r = - 0.597, P < 0.001), bodily pain (r = - 0. 639, P < 0.001), general health (r = - 0.563, P < 0.001), vitality (r = - 0.702, P < 0.001), social functioning (r = - 0.764, P < 0.001), role emotional (r = - 0.675, P < 0.001) and mental health (r = - 0.507, P < 0.001) subscales of the SF-36. An exploratory factor analysis revealed that the 3-factor loading explained 71.558% of the total variance [Kaiser-Mayer-Olkin (KMO) = 0.780, C2 = 502.82, P < 0.001]. CMIN/DF = 1.813, Tucker-Lewis index (TLI) = 0.966 (> 0.9), Comparative Fit Index (CFI) = 0.982 (> 0.9), Normed Fit Index (NFI) = 0.961 (> 0.9), RMSEA = 0.082 (< 0.5) indicating that the model fits well.Conclusion COMI-neck was shown to have acceptable reliability and validity in patients with non-specific chronic neck pain and could be recommended for patients in mainland China.