Sex differences in mortality after an acute coronary syndrome increase with lower country wealth and higher income inequality

Abstract

Introduction and objectives: Although several factors associated with sex differences in the management and outcomes after acute coronary syndrome (ACS) have been reported, little is known about the influence of socioeconomic factors on sex disparities. Our aim was to evaluate the influence of country wealth and income inequality on national sex differences in mortality after ACS.

Methods: Sex differences in 2-year postdischarge mortality were evaluated in 23 489 ACS patients from the EPICOR and EPICOR Asia registries. Adjusted Cox regression models by country-based terciles of gross national income per capita and income inequality were used.

Results: Women (24.3%) were older than men (65.5 vs 59.4 years, P <.001), had more comorbidities, were less often revascularized (63.6% vs 75.6%, P <.001) and received fewer guideline recommended therapies at discharge. Compared with men, a higher percentage of women died during follow-up (6.4% vs 4.9%, P <.001). The association between sex and mortality changed direction from hazard ratio (HR) 1.32 (95%CI, 1.17-1.49) in the univariate assessment to HR 0.76 (95%CI, 0.67-0.87) after adjustment for confounders. These differences were more evident with increasing country wealth (HR_{low-incomecountries} = 0.85; 95%CI, 0.72-1.00; HR_{mid-incomecountries} = 0.66; 95%CI, 0.50-0.87; HR_{high-incomecountries} = 0.60; 95%CI, 0.40-0.90; trend test P = .115) and with decreasing income inequality (HR_{low-inequalityindex} = 0.54; 95%CI, 0.36-0.81; HR_{intermediate-inequalityindex} = 0.66; 95%CI, 0.50-0.88; HR_{high-inequalityindex} = 0.87; 95%CI, 0.74-1.03; trend test P = .031).

Conclusions: Women with ACS living in high socioeconomic countries showed a lower postdischarge mortality risk compared with men. This risk was attenuated in countries with poorer socioeconomic background, where adjusted mortality rates were similar between women and men.

Keywords: Acute coronary syndrome; Desigualdad de ingresos; Diferencias por sexo; Income inequality; Riqueza; Sex differences; Síndrome coronario agudo; Wealth.