Geographic variation in bone mineral density and prevalent fractures in the Canadian longitudinal study on aging

Awareness of the prevalence of osteoporosis and fractures across jurisdictions can guide the development of local preventive programs and healthcare policies. We observed geographical variations in total hip bone mineral density and in the prevalence of major osteoporotic fractures across Canadian provinces, which persisted after adjusting for important covariates.

We aimed to describe sex-specific total hip bone mineral density (aBMD) and prevalent major osteoporotic fractures (MOF) variation between Canadian provinces.

We used baseline data from 21,227 Canadians (10,716 women, 10,511 men) aged 50-85 years in the Canadian Longitudinal Study on Aging (CLSA; baseline: 2012-2015). Linear and logistic regression models were used to examine associations between province of residence and total hip aBMD and self-reported MOF, stratified by sex. CLSA sampling weights were used to generate the prevalence and regression estimates.

The mean (SD) age of participants was 63.9 (9.1) years. The mean body mass index (kg/m²) was lowest in British Columbia (27.4 [5.0]) and highest in Newfoundland and Labrador (28.8 [5.3]). Women and men from British Columbia had the lowest mean total hip aBMD and the lowest prevalence of MOF. Alberta had the highest proportion of participants reporting recent falls (12.0%), and Manitoba (8.4%) the fewest (p-value=0.002). Linear regression analyses demonstrated significant differences in total hip aBMD: women and men from British Columbia and Alberta, and women from Manitoba and Nova Scotia had lower adjusted total hip aBMD than Ontario (p-values<0.02). Adjusted odds ratios (95% confidence intervals, CI) for prevalent MOF were significantly lower in women from British Columbia (0.47 [95% CI: 0.32; 0.69]) and Quebec (0.68 [95% CI: 0.48; 0.97]) and in men from British Columbia (0.40 [95% CI:0.22; 0.71]) compared to Ontario (p-values<0.03). Results were similar when adjusting for physical performance measures and when restricting the analyses to participants who reported White race/ethnicity.

Geographical variations in total hip aBMD and in the prevalence of MOF between provinces persisted after adjusting for important covariates which suggests an association with unmeasured individual and environmental factors.