Background and purpose: Data on continuous monitoring of stroke risk among different age and ethnic groups are lacking. We aimed to investigate age and ethnic disparities in stroke incidence over time from an inner-city population-based stroke register.
Methods: Trends in stroke incidence and before-stroke risk factors were investigated with the South London Stroke Register, a population-based register covering a multiethnic population of 357 308 inhabitants. Age-, ethnicity-, and sex-specific incidence rates with 95% confidence intervals were calculated, assuming a Poisson distribution and their trends over time tested by the Cochran-Armitage test.
Results: Four thousand two hundred forty-five patients with first-ever stroke were registered between 1995 and 2010. Total stroke incidence reduced by 39.5% during the 16-year period from 247 to 149.5 per 100 000 population (P<0.0001). Similar declines in stroke incidence were observed in men, women, white groups, and those aged>45 years, but not in those aged 15 to 44 years (12.6-10.1; P=0.2034) and black groups (310.1-267.5; P=0.3633). The mean age at stroke decreased significantly from 71.7 to 69.6 years (P=0.0001). The reduction in prevalence of before-stroke risk factors was mostly seen in white patients aged>55 years, whereas an increase in diabetes mellitus was observed in younger black patients aged 15 to 54 years.
Conclusions: Total stroke incidence decreased during the 16-year time period. However, this was not seen in younger age groups and black groups. The advances in risk factor reduction observed in white groups aged>55 years failed to be transferred to younger age groups and black groups.
Keywords: epidemiology; ethnology; incidence; risk factors; stroke.