Association Between Common Infections and Incident Post-Stroke Dementia: A Cohort Study Using the Clinical Practice Research Datalink

PURPOSE: To investigate the association between common infections and post-stroke dementia in a UK population-based cohort. MATERIALS AND METHODS: A total of 60,392 stroke survivors (51.2% male, median age 74.3 years, IQR 63.9–82.4 years) were identified using primary care records from the Clinical Practice Research Datalink (CPRD) linked to Hospital Episode Statistics (HES) with no history of dementia. Primary exposure was any GP-recorded infection (lower respiratory tract infection (LRTI), urinary tract infection (UTI) requiring antibiotics, skin and soft tissue infection requiring antibiotics) occurring after stroke. The primary outcome was incident all-cause dementia recorded in primary care records. In sensitivity analyses, we restricted to individuals with linked hospital records and expanded definitions to include ICD-10 coded hospital admissions. We used multivariable Cox regression to investigate the association between common infections and dementia occurring from 3 months to 5 years after stroke. RESULTS: Of 60,392 stroke survivors, 20,969 (34.7%) experienced at least one infection and overall 4512 (7.5%) developed dementia during follow-up. Early dementia (3 months to 1-year post-stroke) risk was increased in those with at least one GP-recorded infection (HR 1.44, 95% CI 1.21–1.71), with stronger associations when hospitalised infections were included (HR 1.84, 95% CI 1.58–2.14). Late dementia (1–5 years) was only associated with hospitalised, but not with GP-recorded, infections. CONCLUSION: There was evidence of an association between common infections and post-stroke dementia, strongest in the 3–12 months following stroke. Better understanding of this relationship could help inform knowledge of pathways to dementia post-stroke and targeting of preventive interventions.