In this study, the COMI demonstrated good internal consistency, validity, and responsiveness to change in our patient population. Its brevity makes it easier for patients to answer. Its simple scoring and free availability simplifies its administration. For all these reasons, the COMI appears a useful measurement tool of patients' outcomes in daily practice.
The COMI was originally designed by a multinational group as a standardized core of questions that assess briefly but globally patients based outcomes [5
]. The design took into account factors such as breadth of coverage, demonstrated validity and reproducibility, and demonstrated responsiveness, practicality (brevity and low cost), compatibility with widely promoted instruments or batteries, and importance to patients and society. The resulting COMI is comprised of 5 scales already validated and in use in some form in other instruments such as EuroQol, National Health Interview Survey, the North American Spine Society, and American Academy of Orthopedic Surgeons instruments.
The psychometric characteristics of the COMI were established with a study of the COMI prospectively administered to 277 patients with low back pain. It demonstrated good reliability, reproducibility, validity, and sensitivity of the COMI composite score and subscales [18
]. The German [14
], French [19
], and Italian [20
] versions as well as a neck [21
] version of the COMI have been validated. It is recommended as “a suitable instrument for implementation in the Spine Tango Registry or in any other multi-language databases of outcomes in LBP patients
” … “the systematic and widespread use of this version in similar settings might enhance the quality of the follow-up of patients with chronic LBP
]. This instrument is considered in both versions as a practical, reliable, and valid tool and will be of value for international studies and surgical registries.
In 2006, Spanish groups of the Hospital Universitari Vall d'Hebron
(Barcelona) and Fundación Jiménez Díaz
(Madrid) published the validation study of the Spanish COMI [5
]. Their sample included two groups of patients (osteoporotic vertebral fracture and chronic low back pain), and outcomes were evaluated with the Spanish version of COMI and Spanish well-validated versions of SF-36, SF-12, and Oswestry Disability Index. The COMI showed good reproducibility, internal consistency, construct validity, and responsiveness, comparable to the more generally used outcome measurements.
The present study examined the use of the COMI in patients with various spine pathologies as typically encountered in daily clinical practice. An important methodological limitation of our study is the lack of test-retest study to confirm the reproducibility of the COMI in our population. Our retrospective analysis did not allow for a test-retest study. Otherwise, just as in the Spanish, German, Italian, and French validation studies, the results of our studies showed similarly good internal consistency, construct validity, and sensitivity to change.