Performance of osteoporosis risk indices in a Japanese population

Abstract

Background: Simple risk assessment questionnaires have been designed to increase awareness of osteoporosis and encourage the appropriate use of bone mineral density (BMD) measurements. However, these tools were developed based on populations that were primarily Caucasian or from other Asian countries, and their applicability to Japanese women is uncertain. Moreover, the BMD criterion for diagnosing osteoporosis in Japan (spinal BMD <70% of the young adult mean) is different from that used in most other countries (BMD T scores ≤−2.5 or ≤−2.0). Objective: The purpose of this study was to evaluate the ability of 4 existing osteoporosis risk assessment tools to identify women with osteoporosis (defined as spinal BMD <70% of the young adult mean) in a sample of postmenopausal Japanese women. Methods: Four osteoporosis risk indices—the Female Osteoporosis Self-Assessment Tool for Asians (FOSTA), the Osteoporosis Risk Assessment Index, the Simple Calculated Osteoporosis Risk Estimation, and SOFSURF—were calculated in 1127 postmenopausal women aged 47 to 91 years enrolled in the Adult Health Study in Hiroshima. Spinal BMD was measured using dual-energy x-ray absorptiometry to confirm or rule out osteoporosis. Results: The prevalence of osteoporosis increased with age, and one third of all women aged ≥70 years had osteoporosis. All 4 risk assessment tools performed similarly in identifying women with osteoporosis, with specificity between 38% and 43% when sensitivity was selected to be ∼90%. Using 3 risk categories (high, intermediate, and low) of the FOSTA, 43% of the high-risk women had osteoporosis as measured by BMD using the Japanese criterion, compared with only 24% and 5% of the intermediate-risk and low-risk women, respectively. Conclusions: The prevalence of osteoporosis is high among older Japanese women, as in other populations. The 4 indices evaluated performed well in classifying the risk of osteoporosis among postmenopausal Japanese women. Applying these assessment tools may encourage appropriate use of BMD technology.