Elsevier

Bone

Volume 71, February 2015, Pages 237-243
Bone

Original Full Length Article
Ten-year incident osteoporosis-related fractures in the population-based Canadian Multicentre Osteoporosis Study — Comparing site and age-specific risks in women and men

https://doi.org/10.1016/j.bone.2014.10.026Get rights and content

Highlights

  • Major osteoporotic fractures increased with age at all sites in women but for men, only hip fracture were age-related.

  • Hip fracture risks were similar in men and women older than 75 years at baseline who were initially community-dwelling.

  • Competing mortality exceeded fracture risk in men older than 65 years at baseline.

  • The most common fractures were the forearm for women and the ribs for men.

  • Few population-based data report 10-year incident fractures in adult men and women of all ages.

Abstract

Background

Population-based incident fracture data aid fracture prevention and therapy decisions. Our purpose was to describe 10-year site-specific cumulative fracture incidence by sex, age at baseline, and degree of trauma with/without consideration of competing mortality in the Canadian Multicentre Osteoporosis Study adult cohort.

Methods

Incident fractures and mortality were identified by annual postal questionnaires to the participant or proxy respondent. Date, site and circumstance of fracture were gathered from structured interviews and medical records. Fracture analyses were stratified by sex and age at baseline and used both Kaplan–Meier and competing mortality methods.

Results

The baseline (1995–97) cohort included 6314 women and 2789 men (aged 25–84 years; mean ± SD 62 ± 12 and 59 ± 14, respectively), with 4322 (68%) women and 1732 (62%) men followed to year-10. At least one incident fracture occurred for 930 women (14%) and 247 men (9%). Competing mortality exceeded fracture risk for men aged 65 + years at baseline. Age was a strong predictor of incident fractures especially fragility fractures, with higher age gradients for women vs. men. Major osteoporotic fracture (MOF) (hip, clinical spine, forearm, humerus) accounted for 41–74% of fracture risk by sex/age strata; in women all MOF sites showed age-related increases but in men only hip was clearly age-related. The most common fractures were the forearm for women and the ribs for men. Hip fracture incidence was the highest for the 75–84 year baseline age-group with no significant difference between women 7.0% (95% CI 5.3, 8.9) and men 7.0% (95% CI 4.4, 10.3).

Interpretation

There are sex differences in the predominant sites and age-gradients of fracture. In older men, competing mortality exceeds cumulative fracture risk.

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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