Stroke differences dissolve by race, sex but not age

The incidence and mortality rates of stroke decreased for elderly men, women, blacks and whites over time for participants in the Atherosclerosis Risk in Communities (ARIC) group, a study published July 16 in JAMA showed. But for younger adults, the incidence trend didn’t carry through.

ARIC enrolled almost 16,000 adults ages 45 to 64 years in four communities in the U.S. between 1987 and 1989 with follow-up through 2011. In this study, Silvia Koton, PhD, of Tel Aviv University, and colleagues followed 14,357 black and white participants who were stroke-free at baseline to determine the incidence of stroke hospitalizations and death.

The baseline age was 54.1 years and 55.4 percent of participants were women. More than a third had hypertension, 11.6 had diabetes, 2.8 percent used cholesterol-lowering medications and 25.9 percent were current smokers.

At the nine-year follow-up, they found a 40 percent increase in the proportion of enrollees with hypertension and diabetes, use of cholesterol drugs was more than five times higher and the proportion of smokers had dropped to 14.7 percent.

Seven percent experienced an incident stroke. The incidence rate was 3.73 per 1,000 person years for total stroke; 3.29 per 1,000 person years for ischemic stroke; and 0.49 per 1,000 person years for hemorrhagic stroke. Stroke incidence decreased over time (0.93 per 1,000 person years overall) with similar decreases by race and sex.

But in participants 65 years and older, the absolute decrease was 1.35 per 1,000 person years while for those younger than 65 years, the absolute decrease was 0.09 per 1,000 person years.

The overall age-adjusted mortality rate dropped over time for an absolute decrease of 8.09 per 100 strokes after 10 years and was similar by sex and race. In participants under 65, though, the absolute decrease was 14.19 per 100 strokes after 10 years. Koton et al attributed much of the overall decline in mortality to younger participants.

They suggested that better control of stroke risk factors and improvements in thrombolysis treatments may have contributed to the reduction in stroke incidence rates while decisions to abstain from care by older adults with stroke may have factored into the age-related difference in mortality rates.