Osteoporosis management and fractures in the Métis of Ontario, Canada

We identified significantly lower sex-specific and age-standardized rates of BMD testing among Métis compared to the general population, yet found little difference in fracture rates (both sexes) or pharmacotherapy (women only). Differences in BMD testing disappeared after adjusting for region of residence among women, yet remained significant among men.

Prior research identifies regional differences in BMD testing for osteoporosis based on access to BMD testing sites [23], which are largely located in urban centres [24, 25]. Given that half of Métis citizens, compared to less than 10 % of the general population of Ontario, were found to reside in northern regions with little access to BMD testing, it is not surprising to find that crude as well as sex-specific and age-standardized rates of BMD testing were lower among Métis citizens compared to the general population. This is consistent with prior research on other chronic conditions that has identified lower rates of screening and fewer specialist visits among Métis that may relate to problems with access in remote areas [11‐13, 26‐28]. Indeed, after adjusting for regional variables (region, urban residence, neighbourhood income quintile), differences in rates of BMD testing disappeared among women. However, differences persisted among men. Prior research identifies higher rates of osteoporosis risk factors such as cardiovascular disease, chronic obstructive pulmonary disease, and diabetes among Métis compared to the general population of Ontario [11‐13], and thus, the finding that BMD testing rates were lower among Métis men after adjusting for regional characteristics is puzzling. Indeed, our finding that Métis men had lower age-standardized rates of osteoporosis pharmacotherapy suggests a potential gender gap. Prior research identifies a tight link between BMD testing and osteoporosis treatment initiation [25]. It is thus not surprising to find that lower rates of BMD testing among men would translate into lower rates of pharmacoprevention. Prior research has also found that men have lower rates of post-fracture treatment and glucocorticoid-induced osteoporosis management compared to women [29, 30]. It is thus particularly interesting to find that Métis men have lower rates of BMD testing after adjusting for regional differences in access, compared with men in the general population. Further research to better understand the reasons for lower rates of BMD testing and osteoporosis treatment among Métis men compared to the general population of men is of interest.

Access to BMD testing has been shown to impact pharmacotherapy [25] and thus is proposed to lead to potential inequities in fracture prevention. One interpretation of our findings may therefore be to improve access to BMD testing in northern and rural areas of Ontario. However, despite finding lower age-adjusted rates of BMD testing (both sexes) and pharmacotherapy (men only) among Métis citizens compared to the general population, fracture rates were found to be similar. Although this finding is comforting, our results are limited by not including vertebral fractures. Vertebral fractures are the most common type of osteoporotic fracture and cause significant morbidity [20]; however, less than half come to clinical attention [31, 32]. For this reason, healthcare administrative data are limited in ability to capture vertebral fractures. It is thus possible that a closer examination with X-rays could identify significant differences in vertebral fractures and thus osteoporosis morbidity, particularly among Métis men. Nonetheless, our finding of little difference in fracture rates between the Métis population and general population of Ontario is consistent with prior research that found similar prevalence of osteoporosis or fracture among Métis and all other residents in Manitoba [33]. However, our results contradict findings from research conducted with larger groups of Aboriginal peoples in Manitoba that document significantly higher fracture rates among First Nations after adjusting for age, sex, income, and geographical residence area [34]. Both studies from Manitoba included vertebral fractures, and differences in vertebral fractures among First Nations were largely identified in younger age groups compared to our study that focused on adults aged 50 or more years [34]. Higher fracture rates among First Nations people in Manitoba are proposed to be related to higher prevalence of diabetes, comorbidity, and substance abuse [35] and a higher rate of accidental and non-accidental trauma [34]. Further research into the burden of osteoporosis among distinct groups of Aboriginal peoples (First Nations, Inuit, and Métis) is of interest. Results from Manitoba identified that First Nations people are less likely to receive a BMD test or pharmacotherapy within 6 months post-fracture [36], yet are at higher risk for post-fracture mortality [37]. Due to the small number of Métis citizens with fractures in our study, we were unable to examine post-fracture osteoporosis management or adherence to therapy.

We acknowledge that our study is subject to some limitations. First, given that the Métis citizenship registry is voluntary and requires individuals to provide proof of ancestry, it may not capture the entire Métis population in Ontario and thus misclassify some Métis in the general population. In comparison to the 2011 National Household Survey, our cohort of Métis citizens represents approximately 25 % of the equivalently aged Métis in Ontario and is represented by more men (55 vs. 49 % in the National Household Survey) [3]. Registration with the Métis Nation of Ontario permits citizens to apply for Harvesters Certification that allows holders to hunt and fish [38], a benefit that may be more appealing to male Métis. Nonetheless, by completing analyses separately for men and women and standardizing by age, we were able to adjust for any sex- and age-related differences. In addition, although Métis people not registered with the Métis Nation of Ontario, as well as other Aboriginal peoples (First Nations and Inuit), would be included with the general population estimates, we anticipate little overall impact on estimates of osteoporosis management in the general population since these Aboriginal groups are few in number compared to the large population of older adults in Ontario. Second, the Ontario Drug Benefit database is limited to individuals aged ≥65 years, and thus, we did not have pharmacy data for younger patients. Although we could have restricted our study to persons aged ≥65 years, including men and women aged 50 or more years in our study permitted a more comprehensive comparison of BMD testing and fracture rates. Third, our study was limited by a relatively small sample size of Métis men and women aged 50 or more years, with few overall fractures, and we were unable to examine other osteoporosis risk factors, such as glucocorticoid exposure that may differentially impact osteoporosis management in the Métis and the general population. Finally, our data did not capture vertebral fractures, and thus, we may underestimate differences in rates of some osteoporotic fractures between Métis citizens and the general population. Despite these limitations, we have significant strength in our ability to leverage data for the province of Ontario and in working with the Métis Nation of Ontario and the Public Health Agency of Ontario in their efforts to better understand Métis health.

As the Métis Nation of Ontario registry and other Métis registries grow across Canada, future research may be able to examine comparative rates of osteoporosis management and fractures in a larger and more representative sample of Métis citizens, and in particular, post-fracture osteoporosis management. We recommend that future research aim to clarify the burden of osteoporosis management among different Aboriginal groups, particularly among men; and examine whether regional variation in access to services, such as BMD testing in rural and remote locations, translate into important differences in post-fracture management and adherence to osteoporosis pharmacotherapy.