Association between socioeconomic status and survival after a first episode of myocardial infarction

Background: A low socioeconomic status is associated with higher overall mortality rates. Aim: To assess the effect of socioeconomic inequalities on survival of patients hospitalized with a first myocardial infarction. Material and Methods: Analysis of hospital discharge and mortality databases of the Ministry of Health. Patients aged over 15 years discharged between 2002 and 2011 with a first myocardial infarction (code I-21, ICD-10) were identified. Their survival was verified with the mortality registry. Survival from 0 to 28 and from 29 to 365 days was analyzed. Socioeconomic status was determined using the type of health insurance, stratified as public insurance (low and medium status) and private insurance (high status). Prais-Winsten trend (P-W) and Cox survival analyses were done. Results: We analyzed 59,557 patients (69% males). Sixty three percent were of low socioeconomic status, 19% medium and 18% high. Between 2002 and 2011 the increase in survival was higher among patients of low socioeconomic status, mainly in women (P-W coefficients 0.58:0.31-0.86 in men and 1.12:0.84-1.41 in women for 0-28 days survival and 0.24:0.09-0.39 in men and 0.48:0.37-0.60 in women for 29-365 days survival, respectively). However, age and year of hospitalization adjusted analysis showed a higher mortality risk among patients of low socioeconomic status at 0-28 days ( HR 1.67:1.53-1.83 for men and 1.49:1.34-1.66 for women) and at 29-365 days (HR 2.30: 1.75-2.71 for men and 1.90:1.56-1.85 for women). Conclusions: Survival after a myocardial infarction improved in the last decade especially in patients of low socioeconomic status. However, subjects of this stratum continue to have a higher mortality.Fondo concursable para el apoyo a la investigación, Insituto de Salud Poblacional - Escuela de Salud Pública, Facultad de Medicina, Universidad de Chile