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

ABSTRACT

OBJECTIVE: To 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. METHODS: Data 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. RESULTS: Among 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. CONCLUSIONS: Socioeconomic inequalities were only observed in men in incidence and in survival during the acute phase after an AMI.