Sex differences in outcomes after acute coronary syndrome vary with age: a New Zealand national study

Aims: This study investigated age-specific sex differences in short- and long-term clinical outcomes following hospitalization for a first-time acute coronary syndrome (ACS) in New Zealand (NZ).

Methods and results: Using linked national health datasets, people admitted to hospital for a first-time ACS between January 2010 and December 2016 were included. Analyses were stratified by sex and 10-year age groups. Logistic and Cox regression were used to assess in-hospital death and from discharge the primary outcome of time to first cardiovascular (CV) readmission or death and other secondary outcomes at 30 days and 2 years. Among 63 245 people (mean age 69 years, 40% women), women were older than men at the time of the ACS admission (mean age 73 vs. 66 years), with a higher comorbidity burden. Overall compared with men, women experienced higher rates of unadjusted in-hospital death (10% vs. 7%), 30-day (16% vs. 12%) and 2-year (44% vs. 34%) death, or CV readmission (all P < 0.001). Age group-specific analyses showed sex differences in outcomes varied with age, with younger women (<65 years) at higher risk than men and older women (≥85 years) at lower risk than men: unadjusted hazard ratio of 2-year death or CV readmission for women aged 18-44 years = 1.51 [95% confidence interval (CI) 1.21-1.84] and aged ≥85 years = 0.88 (95% CI 0.83-0.93). The increased risk for younger women was no longer significant after multivariable adjustment whereas the increased risk for older men remained.

Conclusion: Men and women admitted with first-time ACS have differing age and comorbidity profiles, resulting in contrasting age-specific sex differences in the risk of adverse outcomes between the youngest and oldest age groups.