Original Full Length ArticleTen-year incident osteoporosis-related fractures in the population-based Canadian Multicentre Osteoporosis Study — Comparing site and age-specific risks in women and men
Introduction
Fractures are the primary health risk of osteoporosis [1], [2]. The costs of acute and chronic care following fractures, especially those at the hip, comprise a major portion of national health-care budgets. In 2005, fractures in the USA were associated with an estimated $17 billion dollars in direct costs [3]. A portion of the post-fracture economic burden includes rehabilitation [4], [5], the cost for the increased risks of long-term disability with resulting required increased support [5], [6], decreased health-related quality of life [7] including the development of depression in older women [8] and increased mortality [9]. Thus considerable resources might be allocated toward fracture prevention without exceeding those incurred following a fracture [10].
The FRAX tool, developed to predict the 10-year risk of hip fracture and “major osteoporotic fracture” (MOF, defined as fractures at the hip, distal forearm, clinical vertebral, and proximal humerus) [11], [12], was based on combined data from several international cohorts [12]. Calibration of the Canadian FRAX tool used Canadian national hospital hip fracture data [13] with estimated major osteoporotic fracture rates [14].
The FRAX assessment of major osteoporotic fracture has been established as a standard outcome and measure of burden of disease. Implicit to the FRAX algorithm deriving 10-year fracture probability estimates is an adjustment for the competing risk of death. Furthermore, the FRAX tool considered risk of major osteoporotic fracture as a summary measure, but other fracture sites contributing to the overall burden of osteoporosis include the pelvis, rib and leg [15]. Rib fractures are common in both men and women, are associated with classic osteoporosis risk factors, and are a risk factor for future fracture [16], [17], [18], [19], [20]. The high-frequency of fractures at sites other than the hip and spine is associated with high health care utilization [21]. In short, the population health burden of osteoporotic fractures includes more skeletal sites than major osteoporotic fracture sites and is also potentially modified by competing mortality.
Our purpose was to describe the site-specific 10-year risk of fracture by sex, age at baseline, fracture site and degree of trauma with and without consideration of competing mortality risk in a national population-based cohort.
Section snippets
Study population
The Canadian Multicentre Osteoporosis Study (CaMos) is an ongoing national population-based cohort study initiated in 1995. CaMos design, questionnaires and baseline data acquisition have previously been described [22]. Briefly, recruited community dwelling participants lived within a 50-kilometer radius of one of the nine Canadian cities (St John’s, Halifax, Quebec City, Toronto, Hamilton, Kingston, Saskatoon, Calgary and Vancouver) and were able to converse in English, French or Chinese (in
Results
The study sample consisted of 6314 women and 2789 men with a follow-up duration from study entry to study exit (first fracture, death, or study discontinuation) of 50,300 person-years in women and 21,800 person-years in men. The study sample excluded 186 women and 62 men who did not meet the initial age eligibility criteria (< 85 years) and 39 women and 33 men who did not have at least one year of follow-up. A total of 4322 (68%) women and 1732 (62%) men were still alive and in the cohort at year
Discussion
This study describes the 10-year cumulative incidence of osteoporosis-related fracture by sex, age, trauma and site in a North American country-wide, population-based community dwelling cohort. Hip fracture risks were similar in the oldest community-dwelling men and women. Fragility fractures show a stronger age gradient than do fractures of all traumas in both men and women. We documented that the predominant site of fracture in women is the forearm, while in men the predominant site is the
Disclosures
CaMos is currently funded by: Canadian Institutes of Health Research (CIHR), Amgen, Dairy Farmers of Canada, Merck, Eli Lilly, and Novartis.
D Goltzman has been an advisory board member or consultant for Amgen, Eli Lilly, Merck Frosst, and Novartis; CS Kovacs has received honoraria for advisory boards, consultancies, or speaker's fees from Amgen, Danone, Eli Lilly, Merck, and Novartis; SM Kaiser has received honoraria or educational and research grants from Sanofi-Aventis, Warner Chilcott,
Acknowledgments
The CaMos Research Group: David Goltzman (co-principal investigator, McGill University), Nancy Kreiger (co-principal investigator, Toronto), Alan Tenenhouse (principal investigator emeritus, Toronto), Suzette Poliquin (national coordinator emeritus).
CaMos Coordinating Centre, McGill University, Montreal, Quebec: Suzanne Godmaire (research assistant), Silvia Dumont (administrative assistant), Claudie Berger (study statistician), Lisa Langsetmo (Fellow), CaMos Imaging Centre, Quebec City, Quebec:
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