Quality of life in osteoporosis: reliability, consistency, and validity of the Osteoporosis Assessment Questionnaire

OBJECTIVE: To determine the reliability, consistency, and clinical utility of the Osteoporosis Assessment Questionnaire (OPAQ), an AIMS2 based self-assessment questionnaire. METHODS: Reliability of individual questions, scales, and domains were evaluated in 40 subjects by test-retest and intraclass correlation coefficients and internal consistency by Cronbach's alpha. Construct validity was evaluated by disease state. The relationships between domains and scales were modeled by confirmatory factor analysis. RESULTS: Mean kappa (79 questions) and intraclass correlation (18 health scales) coefficients were 0.58+/-0.16 (mean+/-SD) and 0.82+/-0.07, respectively. Internal consistency was greater than 0.8 in all but 3 scales. Construct validity was confirmed. Patients with hip fracture recorded lower OPAQ scores than patients with vertebral fracture. Correlation and confirmatory factor analyses grouped the 18 health scales into 7 domains. CONCLUSION: These findings suggest that OPAQ is a reliable, consistent, and valid instrument capable of distinguishing hierarchy of functional loss in disease states in osteoporosis.