Educational inequality in cardiovascular disease depends on diagnosis: A nationwide register based study from Denmark

BACKGROUND: Social inequality is present in the morbidity as well as the mortality of cardiovascular diseases. This paper aims to quantify and compare the level of educational inequality across different cardiovascular diagnoses. DESIGN: Register based study. METHODS: Comparison of the extent of inequality across different cardiovascular diagnoses requires a measure of inequality which is comparable across subgroups with different educational distributions. The slope index of inequality and the relative index of inequality were applied for measuring inequalities in incidence of six cardiovascular diagnoses: ischaemic heart disease, acute myocardial infarction, valvular heart disease, congestive heart failure, atrial fibrillation and stroke in the period 2005-2009. All individuals in the general Danish population aged 35-84 years were followed in national registers regarding hospitalisation, death and education from 1985 to 2009 (annual average of 2.9 million people) to define incident cases. RESULTS: Marked educational inequality was found in the incidence of ischaemic heart disease, acute myocardial infarction, heart failure and stroke (relative index of inequality: 0.37 (95% confidence interval 0.34; 0.40) to 0.60 (0.57; 0.63), absolute index of inequality: -241 (-254.4; -227.4) to -37 (-42.7; -31.1)) while inequality in atrial fibrillation and, in particular, in valvular heart disease was small and insignificant (relative index of inequality: 0.57 (0.49; 0.65) to 0.97 (0.88; 1.08), absolute index of inequality: -29 (-35.1; -21.9) to -1 (-4.8; -3.8)). CONCLUSION: The degree of educational inequality in cardiovascular diseases depends on the diagnosis, with the highest inequality in ischaemic heart disease, acute myocardial infarction, heart failure and stroke. Small differences were found between men and women.