FRAX Tool Badly Underestimated Diabetics’ Fracture Risk in Study

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SAN DIEGO – The World Health Organization's widely used, Web-based fracture risk assessment tool, known as FRAX, seriously underestimates the risk of major osteoporotic and hip fractures in patients with diabetes, according to a large Canadian study. This finding indicates diabetes is a risk factor for fractures beyond those in the FRAX tool, which include age, gender, smoking, fracture history, and glucocorticoid use – but not diabetes. “One implication of our findings is that FRAX should be applied cautiously in clinical situations involving diabetic patients,” Lora Giangregorio, Ph.D., said at the annual meeting of the American Society for Bone and Mineral Research. “Future iterations of the FRAX tool might consider adding diabetes to the list of risk factors,” added Dr. Giangregorio of the University of Waterloo (Ontario). She presented an analysis of a database from 3,518 patients with type 1 or type 2 diabetes and 36,085 nondiabetic controls, all at least 50 years old when they underwent bone-density testing during 1987–2008. She and six coauthors subsequently published the study online in the Journal of Bone and Mineral Research (DOI: 10.1002/jbmr.556). FRAX was used to calculate 10-year fracture-risk probabilities, and the actual incidence of major osteoporotic or hip fractures was determined through 2008. The key finding: After the researchers controlled for FRAX fracture probability scores and the use of osteoporotic medications, diabetes was independently associated with a 59% increased fracture rate during an average 10 years of follow-up. Of note, despite the increased fracture rate documented in diabetic patients in this study, a lower proportion of subjects with diabetes were receiving osteoporotic medications, compared with the nondiabetes population, Dr. Giangregorio observed. Diabetes was a stronger predictor of hip fracture risk in the younger study participants. Indeed, it was independently associated with a 5.3-fold increased risk of hip fracture in individuals younger than age 65, compared with a 2.1-fold increase in those who were older. In contrast, the risk of major osteoporotic fractures in diabetic patients was not related to age. An important area for future research, in Dr. Giangregorio's view, is whether some diabetes medications are associated with an increase in fractures while others are not. In another study presented at the meeting, Dr. Ling Oei of Erasmus University, Rotterdam, the Netherlands, noted that patients with type 2 diabetes are paradoxically at increased risk of osteoporotic fractures even though their bone mineral density is typically normal or even higher. In a prospective, population-based study of 203 patients with adequately controlled type 2 diabetes, 217 others with inadequately controlled disease, and 3,715 nondiabetic controls, Dr. Oei and coworkers showed that women with inadequately controlled diabetes had significantly higher bone mineral density at both the lumbar spine and femoral neck, but a 1.6-fold increased risk of fracture during an average 8.2-year follow-up. Dr. Giangregorio and Dr. Oei reported having no financial conflict.