Ten-year incident osteoporosis-related fractures in the population-based Canadian Multicentre Osteoporosis Study - comparing site and age-specific risks in women and men

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.

Keywords: 10-year fracture incidence; Clinical vertebral fracture; Fracture prediction; Hip fracture; Population-based; Sex.

Fig. 1

The distribution of 10-year first incident fractures by sex and skeletal site in the Canadian Multicentre Osteoporosis Study cohort. “Other” includes cervical, pelvis, clavicle, scapula and coccyx.

Fig. 2

(a) Estimated 10-year risk of fragility fracture (low-trauma, equivalent to fall from standing height or less; all sites except the head, hands, ankles and feet) adjusted for competing mortality by sex and baseline age group along with estimated (b) percent of all fracture risk (of any trauma) from the Canadian Multicentre Osteoporosis Study. Error bars indicate 95% CI.

Fig. 3

(a) Estimated 10-year risk of major osteoporotic fracture (MOF 4 sites: hip, clinical spine, forearm, humerus; including all degrees of trauma) adjusted for competing mortality by sex and baseline age group along with estimated (b) percent of fracture risk (at all skeletal sites except the head, hands, ankles and feet) from the Canadian Multicentre Osteoporosis Study. Error bars indicate 95% CI.

Fig. 4

Estimated 10-year risk of fracture (including all degrees of trauma) adjusted for competing mortality by fracture site (clinical spine, hip, forearm, humerus, ribs and leg), sex and baseline age group from the Canadian Multicentre Osteoporosis Study. Estimates are shown by the solid lines, dotted lines indicate the 95% CI.