Socioeconomic differences in incidence and relative survival after a first acute myocardial infarction in the Basque Country, Spain

Abstract

ObjectiveTo estimate the incidence and 28-day and 5-year survival rates after a first acute myocardial infarction (AMI) in relation to socioeconomic status in the Basque Country (Spain) between 1999 and 2000. MethodsData from a population-based registry of AMI were used. The study included 3,619 patients to calculate age-standardized incidence by the direct method and 2,003 patients (out-of-hospital deaths were excluded) to calculate observed and relative survival using the Kaplan-Meier and Hakulinen methods, respectively. Socioeconomic status was quantified using a deprivation index ecologically assigned to each patient according to the census tract of residence at diagnosis of AMI and was categorized into quintiles. ResultsAmong men, the risk of AMI was higher in the lowest socioeconomic group than in the highest socioeconomic group (RR=1.17; 95%CI: 1.02-1.34). In men, a higher risk of death was observed in the middle (Q3; HR=1.60; 95%CI: 1.02-2.51) and low (Q5; HR=1.65; 95%CI: 1.02-2.69) quintiles compared with the least deprived group for age-adjusted survival during the acute phase. In the fully adjusted model, this effect was attenuated and no significant differences were observed in long-term survival. Among women, no significant differences were observed either in incidence or in short- and long-term survival. ConclusionsSocioeconomic inequalities were only observed in men in incidence and in survival during the acute phase after an AMI.