Development of the osteoporosis assessment questionnaire—physical function (OPAQ-PF): an osteoporosis-targeted, patient-reported outcomes (PRO) measure of physical function

SUMMARY: We have developed a short, patient-reported outcome questionnaire—the Osteoporosis Assessment Questionnaire—Physical Function (OPAQ-PF)—that assesses the impact of osteoporosis on physical function. OPAQ-PF contains 15 items in three domains (mobility, physical positions, and transfers) and has content validity in osteoporosis patients with and without a history of fracture. INTRODUCTION: This paper describes the development of the Osteoporosis Assessment Questionnaire—Physical Function (OPAQ-PF), a patient-reported outcome (PRO) questionnaire based on OPAQ v.2.0 (60 items, 14 domains) that assesses the impact of osteoporosis on physical function. METHODS: OPAQ v.2.0 was administered to patients with osteoporosis. Item response theory methodology and clinical judgment were used to retain/eliminate items. The resulting instrument was modified during two sets of concept elicitation and cognitive debriefing interviews with osteoporosis patients. RESULTS: Item response theory-based analysis of OPAQ v.2.0 (n = 1,478) coupled with clinician input resulted in the generation of a 21-item, six-domain instrument with a frequency response format. Interview data from 32 participants were used to modify this version and led to generation of the final instrument, OPAQ-PF. This final version has a severity response format and contains 15 items in three domains (mobility, physical positions, and transfers) that group together to provide an overall assessment of physical function in patients with osteoporosis. Twenty-two of the 32 interview participants (69 %) had previously sustained a fracture. Symptoms occurred primarily in these patients. CONCLUSIONS: OPAQ-PF represents a brief, focused, PRO instrument that assesses physical function in patients with osteoporosis, specifically related to mobility, physical positions, and transfers. This questionnaire has content validity in osteoporosis patients who have, and have not, sustained a prior fracture.