Reliability and validity of the Polish version of the Core Outcome Measures Index for the neck

Abstract

Purpose: Patient reported outcome measures play an increasingly important role in the outcomes research. The Core Outcome Measures Index (COMI) is a short, multidimensional instrument initially developed for the use by patients with low back pain. This study is an evaluation of a Polish version of COMI adapted for neck pain. Methods: One hundred twenty-three patients complaining of neck pain were enrolled. All of them completed a questionnaire booklet containing COMI-neck, Neck Disability Index and Likert-type questions regarding the frequency of use of pain medications and pain frequency. Ninety-eight patients returned the retest questionnaire. Data quality was also assessed. Assessment of psychometric properties included examination of data quality, construct validity, test-retest reliability and factor analysis. Results: The quality of data was good with no missing answers and a little floor effect. Exploratory factor analysis revealed a single-factor structure. Reliability expressed as intraclass correlation coefficient was 0.88 (95 % CI 0.84-0.92) for the overall COMI score and was generally good for most of individual core items. The minimum detectable change (MDC95%) was 1.97. Conclusion: This version of the COMI-neck is a valid and reliable instrument, with good psychometric properties. It can be recommended for Polish-speaking patients. © 2013 The Author(s).