Prevalence of poststroke cognitive impairment: South London Stroke Register 1995-2010

Abstract

Background and purpose: Stroke is a common long-term condition with an increasing incidence as the population ages. This study evaluates temporal changes in the prevalence of cognitive impairment after first-ever stroke stratified by sociodemography, vascular risk factors, and stroke subtypes, up to 15 years after stroke.

Methods: Data were collected between 1995 and 2010 (n=4212) from the community-based South London Stroke Register covering an inner-city multiethnic population of 271 817 inhabitants. Patients were assessed for cognitive function using Abbreviated Mental Test or Mini-Mental State Examination at the onset, 3 months, and annually thereafter. All estimates were age adjusted to the European standard.

Results: The overall prevalence of cognitive impairment 3 months after stroke and at annual follow-up remained relatively unchanged at 22% (24% [95% CI, 21.2-27.8] at 3 months; 22% [17.4-26.8] at 5 years to 21% [3.6-63.8] at 14 years). In multivariate analyses, the poststroke prevalence ratio of cognitive impairment increased with older age (2% [1-3] for each year of age), ethnicity (2.2 [1.65-2.89]-fold higher among black group) and socioeconomic status (42% [8-86] increased among manual workers). A significant, progressive trend of cognitive impairment was observed among patients with small vessel occlusion and lacunar infarction (average annual percentage change: 10% [7.9-12.8] and 2% [0.3-2.7], respectively, up to 5 years after stroke).

Conclusions: The prevalence of cognitive impairment after stroke remains persistently high over time, with variations being predominantly explained by sociodemographic characteristics. Given population growth and ageing demographics, effective preventive strategies and poststroke surveillance are needed to manage survivors with cognitive impairment.