Cross-cultural adaptation and validation of the Thai version of the core outcome measures index for the back (COMI-back) in patients with low back pain.

PURPOSE

To translate and culturally adapt the Core Outcome Measures Index for the back (COMI-back) into Thai and to evaluate its psychometric properties in Thai-speaking patients with low back pain (LBP).

METHODS

The translation process followed a standardized forward-backward method with two independent translators, followed by synthesis and back-translation. An expert committee reviewed the translations for cultural and conceptual equivalence. Pre-testing was done with Thai patients to refine the questionnaire. The validation study included 131 patients with LBP, who completed the Thai COMI-Back along with other validated questionnaires like the Oswestry Disability Index (ODI), and EQ-5D-5L. Reliability was assessed using Cronbach's alpha and intraclass correlation coefficients (ICC). Construct validity was determined by correlating COMI scores with those of reference scales.

RESULTS

The Thai COMI-Back exhibited strong reliability, with Cronbach's alpha values from 0.89 to 0.93 and ICC values over 0.80 for all domains. Construct validity was supported by significant correlations with reference scales, with Spearman's rho values ranging from 0.47 to 0.84. Floor and ceiling effects were acceptable for most items, with notable exceptions for symptom-specific well-being and work disability.

CONCLUSION

The Thai COMI-Back shows strong psychometric properties, making it suitable for clinical and research use in Thailand.