Bone mineral density enhances use of clinical risk factors in predicting ten-year risk of osteoporotic fractures in Chinese men: the Hong Kong Osteoporosis Study

Abstract

This prospective study aimed to determine the risk factors and the 10-year probability of osteoporotic fracture in Southern Chinese men. The findings show substantial population differences in fracture incidence and risk prediction compared to the FRAX(TM) model, and the addition of BMD information to clinical risk factor assessment improved fracture risk prediction in Chinese men.

Introduction: Clinical risk factors with or without bone mineral density (BMD) measurements are increasingly recognized as reliable predictors of fracture risk. Prospective data on fracture incidence in Asian men remain sparse. This prospective study aimed to determine the risk factors and the 10-year absolute fracture risk in Southern Chinese men.

Methods: This is a part of the Hong Kong Osteoporosis Study. One thousand eight hundred ten (1,810) community-dwelling, treatment-naive men aged 50 years or above were evaluated. Baseline demographic characteristics, clinical risk factors and BMD were recorded. Ten-year risk of osteoporotic fracture was calculated using Cox proportional hazards models.

Results: The mean age of subjects was 68.0 ± 10.3 years. After a mean follow-up period of 3.5±2.9 years (range 1 to 14 years), 37 incident low-trauma fractures were recorded. The incidence for all osteoporotic fractures and hip fractures was 635/100,000 and 123/100,000 person-years, respectively. The most significant predictors of osteoporotic fracture were history of fall (RR 14.5), femoral neck BMD T-score < -2.5 (RR 13.8) and history of fracture (RR 4.4). Each SD reduction in BMD was associated with a 1.8 to 2.6-fold increase in fracture risk. Subjects with seven clinical risk factors and BMD T-score of -1 had an absolute 10-year risk of osteoporotic fracture of 8.9%, but this increased to 22.7% if they also had a femoral neck BMD T-score of -2.5.

Conclusions: These findings show substantial population differences in fracture incidence and risk prediction. The addition of BMD information to clinical risk factor assessment improved fracture risk prediction in Chinese men.

Fig. 1

Fracture risks according to different age groups adjusted and unadjusted for competing risk of death

Fig. 2

a Interaction of age with other clinical risk factors and 10-year risk of osteoporotic fracture in Hong Kong Southern Chinese men. b Comparison of 10-year fracture risk prediction with clinical risk factors with or without BMD information in Hong Kong Southern Chinese men (results adjusted for competing risk of death)

Fig. 3

Ten-year risk of osteoporotic fracture in Hong Kong Southern Chinese men according to age and BMD T-score (results adjusted for competing risk of death)

Fig. 4

Ten-year major osteoporotic fracture risk for Hong Kong southern Chinese men according to number of risk factor and femoral neck BMD T-score (results adjusted for competing risk of death)

Fig. 5

Ten-year major osteoporotic fracture risk for Hong Kong Southern Chinese men according to [1] number of risk factors (including BMD) with adjustment for competing risk of death [2] predicted risk by FRAX with femoral neck BMD T-score