Section I: Fracture Risk AssessmentFracture Risk Prediction Using Phalangeal Bone Mineral Density or FRAX®?—A Danish Cohort Study on Men and Women
Introduction
Fractures associated with osteoporosis are very common in the elderly population (1). In Denmark and other countries, a case-finding strategy is adopted recommending general practitioners (GPs) to refer persons with 1 or more risk factors to bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry (DXA); however, a large proportion at high risk of fracture are not diagnosed or treated 2, 3. Central DXA is, furthermore, inaccessible in many countries and regions, and longer distances to DXA facilities seem to be associated with lower use of DXA 4, 5, 6. Also, other methods for measurement of BMD are available. Some of these systems have the advantage of portability, low X-ray exposure, and may be delivered as point of care to identify individuals at high risk of fracture with need of medical checkup and central DXA. Both prospective studies 7, 8, 9, 10, 11, 12, 13 and a meta-analysis (14) have found low peripheral BMD to be associated with increased risk of fracture.
A number of risk factors besides BMD are associated with increased risk of osteoporotic fractures, like age, gender, low body mass index, smoking, excessive alcohol intake, parental hip fracture, and a history of low-energy fracture 1, 15, 16. The Fracture Risk Assessment Tool (FRAX) that predicts the 10-yr probability of hip and major osteoporotic fractures (17) was applied in the clinical management of osteoporosis in some countries; for example, in the United Kingdom where National Osteoporosis Foundation (NOF) recommends treatment based on FRAX (18).
Nevertheless, to our knowledge, no studies have compared the predictive capability of FRAX (without BMD) with a point-of-care densitometer and the combined use of both methods regarding fracture risk prediction. A method holding both the result of the phalangeal densitometer and the 10-yr fracture risk by FRAX would possibly enhance the preselection of person in need of a DXA. In the present prospective study, we, therefore, aimed to investigate the ability of phalangeal BMD using radiographic absorptiometry (RA), FRAX, and age as well as FRAX and BMD in combination in different risk strata to predict osteoporotic fractures.
Section snippets
Material and Methods
We used data on a cohort of women and men aged 18–95 yr who participated in the Danish Health Examination Survey 2007–2008 (DANHES 2007–2008) (19). In short, the study was conducted in 13 of 98 Danish municipalities. All adult citizens aged 18+ yr were invited to answer an Internet-based questionnaire comprising more than 100 items on lifestyle, health, and morbidity. Furthermore, a representative sample of the citizens was invited to participate in a health examination. Overall, 180,103
Results
Complete follow-up information was available on all 12,758 participants, and mean follow-up time was 4.3 yr (range: 0.03–4.9), giving 54,980 person-yr. During follow-up, a total of 395 (3.1%) participants suffered 1 or more major osteoporotic fractures, 54 (0.42%) a hip fracture, and 226 (1.5%) died (data not shown).
Table 2 shows the general characteristic of participants (40.8% men and 59.2% women). With the exception of parental hip fracture and rheumatoid arthritis, the clinical risk factors
Discussion
In this large prospective study, we observed the highest rate of major osteoporotic fractures and hip fracture among persons who had a high 10-yr fracture probability (calculated by FRAX) and a low phalangeal T-score (measured by RA). This was followed by persons only having a low T-score (T-score ≤−2.5). The predictive ability of the different methods showed somewhat inconsistent results depending on what approach we used (analyzed as continuous vs categorical variables based on risk strata).
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