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. Level of evidence Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.