Assessment of absolute fracture risk and osteoporosis in Chinese: is there any difference between the application of Chinese normative database and NHANES III Caucasian database?

Abstract

WHO and ISCD recommend the use of a uniform Caucasian (non-race adjusted) female normative database for women of all ethnic groups as reference for BMD T- scores determination and fracture risk assessment. The objectives of the study were (1) to compare the Southern Chinese and NHANES III normative database in identifying subjects with osteoporosis and fractures in postmenopausal Southern Chinese women in Hong Kong; and (2) to examine the relation of BMD thresholds and clinical risk factors (CRF) evaluation and incident osteoporosis fracture rate and hip fracture rate. 2226 postmenopausal Hong Kong Southern Chinese women aged 45 and above were prospectively followed for incident low trauma fracture. Bone mineral density (BMD) was determined at the hip and spine by dual-energy X-ray absorptiometry (DXA). New fractures were recorded and verified by either retrieval of x-ray report or from the computerised patient record system of the Hospital Authority of the Hong Kong Government. The mean age at baseline was 62.1 ± 9.3 yr. After 4.3 ± 2.2 yr (range 3-12 yr) of follow-up, 137 new osteoporotic fractures were reported. Compared to Southern Chinese database, NHANES III Caucasian female database at the femoral neck overestimated the percentage of women with osteoporosis (18.2%vs 28.8%). However, the overall osteoporotic fracture rate and hip fracture rate were similar between the two reference databases. Although fracture rates were highest in women with femoral neck BMD T-score ≤ -2.5 SD, these women only experienced 56% of the osteoporotic fractures and 61% of the hip fractures. Addition of one or more CRF (>65 yr of age, BMI <19, previous fracture, 1 or more falls in the past 12 months, exercise <30min/day) improved the detection rate of osteoporotic fractures to 80% and hip fractures to 88%. Lowering the BMD T score threshold to -2.0 together with CRF further increased the detection rates to 86% and 91% respectively. The NHANES III Caucasian database can be applied to Southern Chinese for absolute fracture risk assessment. BMD T-score threshold at -2.0 together with CRF assessment could identify the majority of women at high risk of osteoporotic fracture.