Background: Despite a greater incidence of ischemic heart disease among individuals over age 65, most cardiovascular research has been focused on the middle-aged adult population. To date no cohort study on this population have been made in Spain. This study is aimed as reviewing the role and methodology of cohort studies as an epidemiological tool absolutely essential for researching the prevalence and incidence of angina, AMI, stroke and the major cardiovascular risk factors.
Methods: Cohort study in three areas of Spain (Lista district in Madrid), Arevalo (Avila) and Begonte (Lugo). Age and sex stratified random sample by based on the municipal censuses of each area and municipality (n = 5.079). Two-stage initial cohort assessment: home survey structured for the screening ischemic heart disease and classic risk factors (hypertension, dyslipemia, diabetes and smoking habit) and clinical assessment for case confirmation. In the follow-up phase the MONICA project "cold pursuit" method modified for pinpointing and investigating indicent cases was used, employing all of the hospital and primary care clinical records for confirming the cardiovascular event. Data was also requested from the Spanish National Institute of Statistics as to the cause and date of death of the deceased individuals in the cohort.
Results: The overall AMI prevalence was 4% (95% CI: 3.4%, 4.5%); definite plus probable AMI being 6.2% (95% CI: 5.5-6.9). The definite AMI prevalence was higher among the mean 6.7% (95% CI: 5.63-7.79) than among the women, 2% (95% CI: 1.51-2.55) (p < 0.001). Hypertension prevalence according to JNCV1 criteria was 68%, hypercholesterolemia 26.4% according to NCEP criteria, diabetes prevalence 13.4% according to WHO criteria, and 11.3% were smokers. The cumulative incidence for a 3.2-year period for nonfatal definite AMI was 1.4% (95% CI: 1.1-1.8); 1.1% (95% CI: 0.74-1.37) probable AMI: 1.17 (IC95%: 0.824-1.48) for fatal definite AMI or death due to AMI and 1.13% (IC 95%: 0.824-1.48) for sudden death.
Conclusions: The elderly population included in this study shows a high prevalence of cardiovascular risk factors, as well as ischemic heart disease incidence rates three times higher than those of the middle-aged adult population in Spain. The risk profile for women is significantly worse than for men, which may be due to the higher death rate at earlier ages among men.