Does First Nations ancestry modify the association between gestational diabetes and subsequent diabetes: a historical prospective cohort study among women in Manitoba, Canada.

BACKGROUND: Over the past 30 years, the prevalence of diabetes has steadily increased among Canadians, and is particularly evident among First Nations (FN) women. The interplay between FN ancestry, gestational diabetes and the development of subsequent diabetes among mothers remains unclear. METHODS: After excluding known pre-existing diabetes, we explored whether FN ancestry may modify the association between gestational diabetes and post-partum diabetes among women in Manitoba (1981-2011) via a historical prospective cohort database study. We analysed administrative data in the Population Health Research Data Repository using Kaplan-Meier survival analysis and Cox proportional hazards regression. RESULTS: Gestational diabetes was diagnosed in 11 906 of 404 736 deliveries (2.9%), 6.7% of FN and 2.2% of non-FN pregnant women (P < 0.0001). Post-partum diabetes during ≤ 30 years follow-up was more than three times higher among FN women than among non-FN women (P < 0.0001). Diabetes developed in 76.0% of FN and 56.2% of non-FN women with gestational diabetes within the follow-up period. The hazard ratio of gestational diabetes for post-partum diabetes was 10.6 among non-FN women and 5.4 among FN women. Other factors associated with a higher risk of diabetes included lower family income among FN and non-FN women and rural/remote residences among FN women. Among non-FN women, urban residence was associated with a higher risk of diabetes. CONCLUSION: Gestational diabetes increases post-partum diabetes in FN and non-FN women. FN women had substantially more gestational diabetes or post-partum diabetes than non-FN women, partially due to socio-economic and environmental barriers. Reductions in gestational diabetes and socio-economic inequalities are required to prevent diabetes in women, particularly in FN population.

The contributions of First Nations ethnicity, income, and delays in surgery on mortality post-fracture: a population-based analysis.

UNLABELLED: We examined the independent contributions of First Nations ethnicity and lower income to post-fracture mortality. A similar relative increase in mortality associated with fracture appears to translate into a larger absolute increase in post-fracture mortality for First Nations compared to non-First Nations peoples. Lower income also predicted increased mortality post-fracture. INTRODUCTION: First Nations peoples have a greater risk of mortality than non-First Nations peoples. We examined the independent contributions of First Nations ethnicity and income to mortality post-fracture, and associations with time to surgery post-hip fracture. METHODS: Non-traumatic fracture cases and fracture-free controls were identified from population-based administrative data repositories for Manitoba, Canada (aged≥50 years). Populations were retrospectively matched for sex, age (within 5 years), First Nations ethnicity, and number of comorbidities. Differences in mortality post-fracture of hip, wrist, or spine, 1996-2004 (population 1, n=63,081), and the hip, 1987-2002(Population 2, n=41,211) were examined using Cox proportional hazards regression to model time to death. For hip fracture, logistic regression analyses were used to model the probability of death within 30 days and 1 year. RESULTS: Population 1: First Nations ethnicity was associated with an increased mortality risk of 30-53% for each fracture type. Lower income was associated with an increased mortality risk of 18-26%. Population 2: lower income predicted mortality overall (odds ratio (OR) 1.15, 95% confidence interval (CI) 1.07-1.23) and for hip fracture cases (OR 1.18, 95%CI 1.05-1.32), as did older age, male sex, diabetes, and >5 comorbidities (all p≤0.01). Higher mortality was associated with pertrochanteric fracture (OR 1.14, 95% CI 1.03-1.27), or surgery delay of 2-3 days (OR 1.34, 95% CI 1.18-1.52) or ≥4 days (OR 2.35, 95% CI 2.07-2.67). CONCLUSION: A larger absolute increase in mortality post-fracture was observed for First Nations compared to non-First Nations peoples. Lower income and surgery delay>2 days predicted mortality post-fracture. These data have implications regarding prioritization of healthcare to ensure targeted, timely care for First Nations peoples and/or individuals with lower income.

The post-fracture care gap among Canadian First Nations peoples: a retrospective cohort study.

UNLABELLED: Despite targeted attempts to reduce post-fracture care gaps, we hypothesized that a larger care gap would be experienced by First Nations compared to non-First Nations people. First Nations peoples were eight times less likely to receive post-fracture care compared to non-First Nations peoples, representing a clinically significant ethnic difference in post-fracture care. INTRODUCTION: First Nations peoples are the largest group of aboriginal (indigenous or native) peoples in Canada. Canadian First Nations peoples have a greater risk of fracture compared to non-First Nations peoples. We hypothesized that ethnicity might be associated with a larger gap in post-fracture care. METHODS: Non-traumatic major osteoporotic fractures for First Nations and non-First Nations peoples aged ≥ 50 years were identified from a population-based data repository for Manitoba, Canada between April 1996 and March 2002. Logistic regression analysis was used to examine the probability of receiving a BMD test, a diagnosis of osteoporosis, or beginning an osteoporosis-related drug in the 6 months post-fracture. RESULTS: A total of 11,234 major osteoporotic fractures were identified; 502 occurred in First Nations peoples. After adjustment for confounding covariates, First Nations peoples were less likely to receive a BMD test [odds ratio (OR) 0.1, 95% confidence interval (CI), 0.0-0.5], osteoporosis-related drug treatment (OR, 0.5; 95% CI, 0.3-0.7), or a diagnosis of osteoporosis (OR, 0.5; 95% CI, 0.3-0.7) following a fracture compared to non-First Nations peoples. Females were more likely to have a BMD test (OR, 5.0; 95% CI, 2.6-9.3), to be diagnosed with osteoporosis (OR, 1.7; 95% CI, 1.5-2.0), and to begin drug treatment (OR, 4.1; 95% CI, 2.7-6.4) compared to males. CONCLUSIONS: An ethnicity difference in post-fracture care was observed. Further work is needed to elucidate underlying mechanisms for this difference and to determine whether failure to initiate treatment originates with the medical practitioner, the patient, or a combination of both. It is imperative that all residents of Manitoba receive efficacious and equal care post-fracture, regardless of ethnicity.

The interaction of ethnicity and chronic disease as risk factors for osteoporotic fractures: a comparison in Canadian Aboriginals and non-Aboriginals.

INTRODUCTION: Efforts to develop global methods for absolute fracture risk prediction are currently limited by uncertainty over the validity of these models in non-White populations. Aboriginal Canadians have higher fractures rates than non-Aboriginals. This analysis examined the interaction of ethnicity with diabetes mellitus, disease comorbidity and substance abuse as possible explanatory variables. METHODS: A retrospective, population-based matched cohort study of fracture rates was performed using Manitoba administrative health data (1984-2003). The study cohort consisted of 27,952 registered Aboriginal adults (aged 20 years or older) and 83,856 non-Aboriginal controls (matched three to one for year of birth and gender). Diabetes mellitus, number of ambulatory disease groups (ADGs), substance abuse and incident fractures were based upon validated definitions. Poisson regression analyses of fracture rates modelled the explanatory variables as main effects and two-way interactions with ethnicity. RESULTS: Osteoporotic fracture rates were approximately twofold higher in the Aboriginal cohort (p<0.0001). Diabetes, greater number of ADGs and substance abuse were all more common in the Aboriginal cohort (all p<0.0001). These factors were associated with increased fracture rates (all p<0.0001) and significantly higher population attributable risk percent in the Aboriginal cohort (all p<0.0001). However, no significant interactions between the risk factors and ethnicity were observed (p>0.1 for all interaction effects). CONCLUSION: Greater prevalence of diabetes, comorbidity and substance abuse contributes to higher rates of fracture. The relative risk of fracture for these factors is similar for both Aboriginal and non-Aboriginals despite large differences in absolute fracture risk and risk factor prevalence.