Validation of the Iranian Version of the ECOS-16 Questionnaire in Patients with Osteoporotic Vertebral Fractures.

STUDY DESIGN: Prospective clinical study.

PURPOSE: To translate and validate the Quality of Life Questionnaire of the European Foundation for Osteoporosis (ECOS-16) in patients with osteoporotic vertebral fractures in Iran.

OVERVIEW OF LITERATURE: It is important to assess the psychometric properties of instruments measuring patient-reported outcomes.

METHODS: The translation was performed using the backward-forward translation method. The final version was generated by consensus among the translators. Every woman who had a T-score of <-2.5 completed ECOS-16. Patients were divided into two study groups according to the World Health Organization's criteria: those with at least one vertebral fracture (surgery group) and those with no fractures (control group). They were asked to respond to the questionnaire at three points in time: preoperative and twice within 1-week interval after surgery assessments (6-month follow-up). The 36-item short-form health survey (SF-36) also was completed. The psychometric properties of the questionnaire were assessed using internal consistency, test-retest reliability, convergent validity, discriminant validity, and responsiveness.

RESULTS: Of 137 recruited women, 39 underwent surgery and 98 did not. Analysis of the ECOS-16 scales showed an appropriate reliability with Cronbach's alpha of >0.70 for all scales. Test-retest reliability as indicated by intraclass correlation coefficient was found to be 0.85 (0.68-0.91). Additionally, the correlation of each item with its hypothesized domain of the ECOS-16 showed acceptable results, suggesting that the items had a substantial relationship with their own domains. Further analysis also indicated that the questionnaire was responsive to change (effect size, 0.85; standardized response mean, 0.93) (p<0.001). Significant correlations existed between scores of similar subscales of ECOS-16 and SF-36 (p<0.001).

CONCLUSIONS: ECOS-16 is an acceptable, reliable, valid, and responsive measure to assess the quality of life in patients with osteoporotic vertebral fractures.