Social Inequality by Income in Short- and Long-Term Cause-Specific Mortality after Stroke

Abstract

Goals: It is unclear whether social inequality exists for mortality after stroke. Results of studies on the relation between socioeconomic position (SEP) and mortality after stroke have been inconsistent and inconclusive. Material and Methods: We studied the association between SEP expressed by income and the risk of death after stroke by merging data on incident stroke from Danish registries with nationwide coverage. We identified all incident cases of stroke hospitalized in Denmark 2003-2012 (n = 60503). Patients were followed up to 9 years after stroke (median 2.6 years). Adjusting for age and sex we studied all-cause death and cause-specific death by stroke, cardiac disease, cancer, and other diseases certified by death records and stratified by income. Results: Of the patients 20,953 (34.6%) had died within follow-up: Death by stroke 8018 (13.2%); cardiac disease 4250 (7.0%); cancer 3060 (5.0%); other diseases 5625 (9.2%). Long-term mortality rates were inversely related to income for all causes of death. The difference in mortality between the lowest and the highest income group at 5 years after stroke was 15.5% (relative) and 5.7% (absolute). Differences in short-term mortality (1-month to 1-year) between income groups were small and clinically insignificant. Conclusions: Social inequality in mortality after stroke expressed by income was pronounced for long-term mortality while not for short-term mortality. It seems that social inequality is expressed in a greater risk among stroke patients with low income for the advent of new diseases subsequently leading to death rather than in their ability to survive the incident stroke.