Comparison of 30-day readmission rates and 1-year mortality of cardiovascular disease between Australian- and overseas-born residents: a large cohort study of older Australian adults

Type of funding sources: None.

Cardiovascular disease (CVD) is prevalent, causing high hospital readmission rates and mortality. Social determinants of health such as ethnicity and cultural background are known to influence CVD outcomes. However, comparisons of CVD outcomes between Australian- and overseas-born residents for 30-day readmissions and mortality patterns in ischemic heart disease (IHD), heart failure (HF) and stroke, are not well understood.

This study aimed to compare 30-day readmission after hospitalisation due to IHD, HF or stroke and 1-year CVD mortality across three country of birth groups (Australian-born, born in English-speaking countries and born in non-English-speaking countries).

The study group was drawn from the 45 and Up cohort, Australia’s largest ongoing study of health and ageing, consisted of participants free of IHD, HF and stroke at baseline who were admitted to hospital for a CVD-related diagnosis after baseline, linked with hospital admissions (mean follow-up time 11.2 years) and mortality data (mean follow-up time 9.9 years). Risk ratios for 30-day readmission and 1-year CVD mortality across three country of birth groups (Australia, English-speaking countries other than Australia, and non-English-speaking countries) were calculated using binary logistic regression, adjusting for age, sex, socioeconomic status, marital status, age at migration and education.

A total of 39,458 participants were analysed with a mean age of 66.5, of which 54% were male, 13% and 10% were born in English-speaking countries other than Australia and non-English-speaking countries, respectively.

The crude rates for 30-day readmission and 1-year CVD mortality of the overall sample were 32 per 100 and 2.6 per 100. Compared to Australian-born participants, those born in English-speaking countries had a 7 % lower risk of 30-day readmission (RR: 0.93, 95% CI: 0.87-0.99), and those born in non-English-speaking countries had a 16% lower risk (RR: 0.84, 95 CI: 0.78-0.91). No evidence of an association between country of birth and 1-year CVD mortality was found.

Overseas-born Australians regardless of English-language background have a lower risk of 30-day readmission compared to those who are Australian-born when sociodemographic characteristics are adjusted for. However, the 45 and Up Study questionnaire was available only in English. Residents born in non-English-speaking countries with limited English skills were thus less likely to be involved in this study. Further studies should consider other characteristics and potential explanations for this benefit.