Largest ever Canadian study on osteoporosis shows osteoporosis-related fractures increase risk of subsequent fracture independently of low bone mineral density

MONTREAL, QUEBEC | 2008-09-15

Results of the largest ever Canadian study on osteoporosis presented this weekend at the 30th annual American Society for Bone and Mineral Research (ASBMR) meeting in Montreal show that Canadians over 50 years old who experience an osteoporosis-related fracture are at increased risk of a subsequent fracture. The results show fractures predict subsequent fractures independent of low bone mineral density. The results are the newest findings from CaMos (Canadian Multicentre Osteoporosis Study) the largest Canadian study on osteoporosis, which has been following almost 10,000 Canadians for more than 10 years to assess the prevalence and incidence of osteoporosis and associated fractures in Canada as well as the related health and economic impact.

Bone mineral density (BMD) test results have traditionally been used by health professionals to assess risk for osteoporosis and possible resulting fractures. This study, however, showed that a majority of fragility fractures occurred among people with BMD scores above the threshold for diagnosing osteoporosis.

The study results highlight that while a BMD measure low enough for a diagnosis of osteoporosis is a strong risk factor for fracture, patients who have had one fracture are at greater risk for a subsequent fracture, no matter what their BMD measure. In fact, 40 per cent of all osteoporosis-related fractures in Canadian women over 50 years old are repeat fractures, representing an important contribution to the burden placed on the healthcare system from fractures.

What the study findings mean for Canadians over 50 years old is that they need to be actively involved in taking charge of their bone health, said the study's lead investigator, Dr. Sophie Jamal, co-director for the Toronto CaMos Centre and Assistant Professor of Medicine at the University of Toronto, who presented the study abstract at the ASBMR meeting.

Osteoporosis-related fractures lead to life-changing, long-term disability, and this is precisely what we are trying to prevent with CaMos. One of the conclusions we were able to draw from our observations is that traditional BMD risk categories fail to identify some men and women at high fracture risk, as a large number of fractures occur in men and women with BMD levels above those of a diagnosis of osteoporosis, added Dr. Jamal.

Dr. Jamal's study looked at the records of 2,179 men and 5,269 women aged 50 to 90 enrolled in CaMos and included all low trauma fractures that occurred over seven years. Analyses were stratified by sex, fracture status (first vs. repeat) and BMD categories, calculated by what is called a T score, a comparison of the patient's BMD to the optimal BMD for the patient's gender. A T score greater than -1 is considered normal, from -1 to -2.5 is considered osteopenic and at risk for developing osteoporosis, and less than -2.5 is diagnostic of osteoporosis.

CaMos, led by principal investigator Dr. David Goltzman of the McGill University Health Centre, produces data representative of the Canadian population that helps to inform health policy and improve osteoporosis prevention, diagnosis, and treatment in Canada.
Osteoporosis has substantial health and economic impact in Canada - but CaMos has shown that we can do something about it. Health professionals have traditionally relied on BMD test results so it is important to educate Canadians about the importance of fracture history in the diagnosis and treatment of osteoporosis in order to prevent subsequent fractures, states Dr. Goltzman. We now have concrete Canadian data and statistics from CaMos that will enable us to better improve the outcomes of our patients.

Prior to initiating the study, most of the data used to estimate the incidence, prevalence and related costs of osteoporosis in Canada was collected in the United States and Western Europe. While useful, this data did not take into account the specificity of Canada's population, climate and geography. The prevalence and incidence of osteoporosis and related fractures are not only affected by genetics but are dependent on external factors such as climate and socio-demographic characteristics of the population.


CaMos by the numbers: results presented by Dr. Jamal

Among women, 60% were a first fracture and 40% repeat fractures. Considering T-score categories, 10% of fractures occurred with normal BMD, 51% with osteopenic (risk for osteoporosis) BMD, and 39% with osteoporotic BMD.

Among men, 75% of fractures were a first fracture and 25% repeat fractures. Considering T-score categories, 25% of fractures occurred with normal BMD, 54% with osteopenic BMD, and 21% with osteoporotic BMD.


About osteoporosis

Osteoporosis is the most common metabolic bone disease in the elderly. The disease causes the bones to become porous and fragile. It progresses painlessly and without apparent symptoms until a fracture occurs. Osteoporosis affects both men and women.

1.4 million Canadians suffer from osteoporosis
One in four women over the age of 50 has osteoporosis
One in eight men over the age of 50 has osteoporosis
70 per cent of hip fractures are related to osteoporosis
Up to 20 per cent of hip fractures result in death
Up to 50 per cent of hip fractures result in permanent disability
More women die each year as a result of osteoporotic fractures than from breast and ovarian cancer combined


About the Canadian Multicentre Osteoporosis Study (CaMos)

Initiated in 1996, CaMos is a prospective, population-based epidemiologic study involving a collaboration of leading Canadian experts, 10 study centres in 7 provinces and more than 10,000 participants across Canada. CaMos produces reliable Canadian data on the prevalence and incidence of osteoporosis and related fractures as well as the associated health and economic impact. The study also examines bone mineral density and the relationship between socio-demographic characteristics, other exposures, and bone health.

This largest ever Canadian study on osteoporosis, recognized internationally for its validity and quality, features a sample representative of the Canadian population and a long-term perspective with almost 70% retention after 10 years of follow-up. Study results have helped to inform health policy and improve osteoporosis prevention, diagnosis, and treatment in Canada.

The study is funded by the Canadian Institutes of Health Research (CIHR), Merck Frosst Canada Ltd., Eli Lilly Canada Inc., Novartis Pharmaceuticals Inc., The Alliance for Better Bone Health (sanofi-aventis and Procter & Gamble Pharmaceuticals Canada Inc.), Servier Canada Inc., the Dairy Farmers of Canada and the Arthritis Society of Canada. CaMos aims to grow its funding support to $5 million per year to achieve the study's objectives over the next 10 years. For more information on CaMos please visit www.camos.org.

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