Geographic variation of bone mineral density and selected risk factors for prediction of incident fracture among Canadians 50 and older
Lisa Langsetmo, Jerilynn C Prior, Jonathan D Adachi
Christopher S Kovacs, Tassos Anastassiades, David Goltzman, David A Hanley, K Shawn Davison, Nancy Kreiger , Alan Tenenhouse , CaMos Research Group , Sophie A Jamal
Striking geographic variation in the incidence of osteoporotic fracture has been shown in national and international studies. The contributing risk factors for this variation are not fully understood.
Objective
To determine the geographic variation of bone mineral density (BMD) values, prevalent low-trauma fracture, prior falls, and vertebral deformity and to determine how this variation is related to the geographic variation of incident low-trauma fracture.
Methods
We studied incident fracture among 2484 men and 6093 women ages 50 and older from CaMos, a randomly-selected population-based longitudinal cohort recruited from within 50 kilometers of nine cities across Canada. Analyses included up to an eight-year follow-up.
Results
Estimates of fracture incidence are all age-standardized and given per 1000 person-years and CI denotes confidence interval. Among men, the lowest incidence of low-trauma fracture was 3.2 (95% CI: 1.1-7.5) in Quebec and the highest was 11.9 (95% CI: 7.1-18.6) in Calgary, compared with an overall incidence of 7.2 (95% CI: 5.8-8.7). Among women, the lowest incidence of low-trauma fracture was 11.5 (95% CI: 8.5-15.1) in Halifax and the highest was 18.5 (95% CI: 14.6-23.3) in Calgary, compared with an overall incidence of 15.3 (95% CI: 14.1-16.7). The regional variation in low-trauma fractures was similar to variation in hip fracture incidence among women (Pearson correlation, r=0.46 to 0.76) but not men (r=-0.06 to 0.05). We noted significant geographic variation in the prevalence of low BMD, as defined by BMD T-score< or =-2.5, however this variation was not directly related to low-trauma fractures or other risk factors. Furthermore, a model including age, BMD, falls, vertebral deformity, and prior clinical fracture was a good predictor of geographic variation of low-trauma fracture incidence in both men (r=0.66) and women (r=0.84).
Conclusions
For both men and women, the burden of low-trauma fracture is not related to the prevalence of osteoporosis as defined by BMD, but is related to a more comprehensive assessment of fracture risk including the following: age, BMD, falls, prior fracture, and vertebral deformity.
geographic variation BMD, fracture risk regional, bone mineral density Canada, incident fracture prediction, vertebral deformity prevalence, falls risk geographic, CaMos geographic variation, osteoporotic fracture epidemiology, latitude bone density, population-based fracture risk
PMID 18640295 18640295 DOI 10.1016/j.bone.2008.06.009 10.1016/j.bone.2008.06.009
Cite this article
Langsetmo, L., Hanley, D. A., Kreiger, N., Jamal, S. A., Prior, J., Adachi, J. D., Davison, K. S., Kovacs, C., Anastassiades, T., Tenenhouse, A., Goltzman, D., & CaMos Research Group (2008). Geographic variation of bone mineral density and selected risk factors for prediction of incident fracture among Canadians 50 and older. Bone, 43(4), 672-678. https://doi.org/10.1016/j.bone.2008.06.009
Langsetmo L, Hanley DA, Kreiger N, Jamal SA, Prior J, Adachi JD, et al. Geographic variation of bone mineral density and selected risk factors for prediction of incident fracture among Canadians 50 and older. Bone. 2008;43(4):672-678. doi:10.1016/j.bone.2008.06.009
Langsetmo, L., et al. "Geographic variation of bone mineral density and selected risk factors for prediction of incident fracture among Canadians 50 and older." Bone, vol. 43, no. 4, 2008, pp. 672-678.
Our objective was to describe patterns and predictors of sedentary behavior (sitting time) over 10 years among a large Canadian cohort. Data are from the Canadian Multicentre Osteoporosis Study, a prospective study of women and men randomly selected from the general population. Respondents reported socio-demographics, lifestyle behaviors and health outcomes in interviewer-administered questionnaires; weight and height were measured. Baseline data were collected between 1995 and 1997 (n = 9418; participation rate = 42%), and at 5- (n = 7648) and 10-year follow-ups (n = 5567). Total sitting time was summed across domain-specific questions at three time points and dichotomized into "low" (≤ 7 h/day) and "high" (> 7 h/day), based on recent meta-analytic evidence on time sitting and all-cause mortality. Ten-year sitting patterns were classified as "consistently high", "consistently low", "increased", "decreased", and "mixed". Predictors of sedentary behavior patterns were explored using chi-square tests, ANOVA and logistic regression. At baseline (mean age = 62.1 years ± 13.4) average sitting was 6.9 h/day; it was 7.0 at 5and 10-year follow-ups (p for trend = 0.12). Overall 23% reported consistently high sitting time, 22% consistently low sitting, 14% decreased sitting, 17% increased sitting with 24% mixed patterns. Consistently high sitters were more likely to be men, university educated, full-time employed, obese, and to report consistently low physical activity levels. This is one of the first population-based studies to explore patterns of sedentary behavior (multi-domain sitting) within men and women over years. Risk classification of sitting among many adults changed during follow-up. Thus, studies of sitting and health would benefit from multiple measures of sitting over time.
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Population-based administrative data have been used to study osteoporosis-related fracture risk factors and outcomes, but there has been limited research about the validity of these data for ascertaining fracture cases. The objectives (a) compare fracture incidence estimates from administrative data with estimates from population-based clinically-validated data, and (b) test for differences in incidence estimates from multiple administrative data case definitions. Thirty-five case definitions for incident fractures of the hip, wrist, humerus, and clinical vertebrae were constructed using diagnosis codes in hospital data and diagnosis and service codes in physician billing data from Manitoba, Canada. Clinically-validated fractures were identified from the Canadian Multicentre Osteoporosis Study (CaMos). Generalized linear models were used to test for differences in incidence estimates. For hip fracture, sex-specific differences were observed in the magnitude of underand over-ascertainment of administrative data case definitions when compared with CaMos data. The length of the fracture-free period to ascertain incident cases had a variable effect on over-ascertainment across fracture sites, as did the use of imaging, fixation, or repair service codes. Case definitions based on hospital data resulted in under-ascertainment of incident clinical vertebral fractures. There were no significant differences in trend estimates for wrist, humerus, and clinical vertebral case definitions. The validity of administrative data for estimating fracture incidence depends on the site and features of the case definition.