Socioeconomic status and severity of illness on admission in acute myocardial infarction patients

The objective of this research is to test the hypothesis of the existence of an association between socioeconomic status and severity of illness of the patients admitted to the hospital with acute myocardial infarction. The design was a retrospective cohort study of consecutive patients admitted to the coronary care unit with the diagnosis of acute myocardial infarction in six public hospitals from the Spanish region of Valenciá. A total of 369 patients admitted to the intensive care units of the participating hospitals were studied. The socioeconomic status was measured using an ad hoc index based upon the occupational level, income and educational level of the patient. The patients below the 20% percentile were considered as disadvantaged, and the patients whose Killip class on admission was 3 or 4 were considered as complicated. The effect of potential confounders was controlled using unconditional logistic regression analysis. The results were validated in an independent but comparable population of 331 patients. The disadvantaged patients showed a higher prevalence of open cardiac failure on admission (Killip classes 3 or 4) than the remainder (crude odds ratio = 3.1, 95% confidence interval between 1.57 and 6.1). The association between socioeconomic status and severity of illness persisted after controlling for important covariates (age, diabetes mellitus, gender and marital status): adjusted odds ratio = 2.4, 95% confidence interval between 1.1 and 5.2. These results were highly consistent with those in the validation group. Our results suggest that socioeconomic status is an independent predictor of the severity of illness on admission to coronary care units in acute myocardial infarction patients. These results are consistent with the existence of a low accessibility of patients in the lower socioeconomic levels.