Better Indigenous Risk stratification for Cardiac Health study (BIRCH) protocol: rationale and design of a cross-sectional and prospective cohort study to identify novel cardiovascular risk indicators in Aboriginal Australian and Torres Strait Islander adults

Modelling prevalent cardiovascular disease in an urban Indigenous population

OBJECTIVE

Studies have highlighted the inequities between the Indigenous and non-Indigenous populations with respect to the burden of cardiovascular disease and prevalence of predisposing risks resulting from historical and ongoing impacts of colonization. The objective of this study was to investigate factors associated with cardiovascular disease (CVD) within and specific to the Indigenous peoples living in Toronto, Ontario, and to evaluate the reliability and validity of the resulting model in a similar population.

METHODS

The Our Health Counts Toronto study measured the baseline health of Indigenous community members living in Toronto, Canada, using respondent-driven sampling. An iterative approach, valuing information from the literature, clinical insight and Indigenous lived experiences, as well as statistical measures was used to evaluate candidate predictors of CVD (self-reported experience of discrimination, ethnic identity, health conditions, income, education, age, gender and body size) prior to multivariable modelling. The resulting model was then validated using a distinct, geographically similar sample of Indigenous people living in Hamilton, Ontario, Canada.

RESULTS

The multivariable model of risk factors associated with prevalent CVD included age, diabetes, hypertension, body mass index and exposure to discrimination. The combined presence of diabetes and hypertension was associated with a greater risk of CVD relative to those with either condition and was the strongest predictor of CVD. Those who reported previous experiences of discrimination were also more likely to have CVD. Further study is needed to determine the effect of body size on risk of CVD in the urban Indigenous population. The final model had good discriminative ability and adequate calibration when applied to the Hamilton sample.

CONCLUSION

Our modelling identified hypertension, diabetes and exposure to discrimination as factors associated with cardiovascular disease. Discrimination is a modifiable exposure that must be addressed to improve cardiovascular health among Indigenous populations.

Sleep quantity and quality and cardiometabolic risk factors in Indigenous Australians

Poor sleep is associated with increased risk of cardiovascular disease (CVD). Indigenous Australians have 1.3 times higher risk of CVD compared to non-indigenous Australians. However, there are limited data describing sleep problems and cardiometabolic risk in this population. This study aimed to investigate sleep quantity and quality in indigenous Australians and assess its association with cardiometabolic risk. Two hundred and forty-five indigenous Australians aged > 18 years were recruited via convenience sampling from communities in the Northern Territory and Queensland. Sleep quantity and quality was assessed subjectively with questionnaires including the Epworth Sleepiness Scale. In a sub-population (n = 46), objective sleep assessment was performed over three nights of actigraphy. Cardiometabolic risk measures included glycated haemoglobin, lipids, anthropometric measurements and sitting blood pressure. Sleep duration measured subjectively and objectively averaged 7.5 ± 2.0 hr/night; however, over one-third of participants (self-report 35%; actigraphy 39%) obtained < 7 hr/night. Overall, more than a third of participants experienced poor-quality sleep, with 27% reporting severe daytime sleepiness (ESS score > 10) and a high number of objectively measured awakenings/night (6 ± 4). Short sleep duration (<6 hr/night) measured both subjectively and objectively was an independent predictor of diastolic (β = 5.37, p = .038) and systolic blood pressure (β = 14.30, p = .048). More objectively measured night-time awakenings were associated with increased glycated haemoglobin levels (β = 0.07, p = .020) and greater sleep fragmentation was associated with lower high-density lipoprotein levels (β = -0.01, p = .025). A large proportion of indigenous Australians experienced short sleep durations and had significant sleep disruption. Poor sleep quantity and quality may contribute to heightened cardiometabolic risk in this population.

Preventing recurrent events in survivors of acute coronary syndromes in Australia: consensus recommendations using the Delphi process

OBJECTIVE

There remain substantial gaps in implementation of evidence-based care in patients with acute coronary syndromes (ACS) in Australia, which contribute to high recurrent event rates. Improved translation of evidence into effective action is a key health-care priority. We engaged cardiovascular experts from across Australia to develop straightforward, easily actionable recommendations on key medications to use following ACS.

METHODS

An eight-person steering committee (SC) reviewed the published evidence and developed an initial set of statements to be developed into consensus recommendations using a modified Delphi technique. A panel of 21 expert cardiologists in the ACS field (including the SC) voted on their level of agreement with the statements using a 6 point Likert scale. Statements that did not reach consensus (≥80% agreement) were reviewed by the SC, modified as appropriate based on input from the panel and circulated for re-voting.

RESULTS

Twenty-eight statements were developed by the SC across six classes of medication: low-density lipoprotein (LDL) cholesterol lowering agents, aspirin, dual antiplatelet therapy, renin-angiotensin-aldosterone system inhibitors, beta blockers and "other". Twenty-six recommendations were endorsed by the voting panel; two statements did not reach consensus.

CONCLUSIONS

Despite the extensive evidence base and detailed guidelines outlining best practice post ACS, there remain considerable gaps in translating these into everyday care. We used an internationally recognized technique to develop practical consensus recommendations on medical treatment following ACS. These simple, up-to-date recommendations aim to improve evidence-based medication use and thereby reduce the risk of future cardiovascular events for Australian patients with ACS.