Cross-cultural adaption and validation of the Swedish version of the Core Outcome Measures Index for low-back pain.

Purpose: There is a wide selection of instruments and questionnaires available, but many are time consuming in their administration, for patients, practitioners and researchers alike. The Core Outcome Measures Index (COMI) is a short, self-administrated, multidimensional instrument translated into several languages that covers five domains recommended in the assessment of outcome in patients with low-back pain. The purpose of this study was to cross-culturally adapt the COMI from English to Swedish and to test the face and construct validity and reproducibility of its results in patients with low-back pain.
Methods: Participants (n = 102) were included from primary and secondary care. The participants reported moderate pain and disability levels. All participants filled in the COMI, the Oswestry Disability Index and the EQ5D at baseline. Forty-nine filled in the COMI again after 7 days for the reproducibility part of the study.
Results: The instrument was successfully forward and back-translated. In the validation process, there were low floor/ceiling effects, with the exception of the symptom-specific well-being (floor) and work disability (ceiling) items. The specific COMI domains and whole score correlated significantly with the chosen reference scale scores to the hypothesised extent (Rho 0.30-0.60 and > 0.60 respectively). COMI reached ICC 0.63 (95% CI 0.42-0.77) in the reproducibility test and the separate items, ICC 0.41-0.78.
Conclusions: The Swedish COMI shows acceptable psychometric properties and is thus suitable to use as a short instrument for measuring important domains in patients with low-back pain. A future study should investigate the instrument's sensitivity to measure change after treatment. These slides can be retrieved under Electronic Supplementary Material.