Hospital-Acquired Infection at Time of Stroke and Cognitive Decline: The Cardiovascular Health Study

Hospital-acquired infections (HAIs) after stroke are associated with additional morbidity and mortality, but whether HAIs increase long-term cognitive decline in stroke patients is unknown. We hypothesized that older adults with incident stroke with HAI experience faster cognitive decline than those having stroke without HAI and those without stroke.

We performed a longitudinal analysis in the population-based prospective Cardiovascular Health Study. Medicare-eligible participants aged ≥65 years with and without incident stroke had cognition assessed annually. HAIs were assessed by hospital discharge codes. Global cognitive function was assessed annually by the Modified Mini-Mental State Examination (3MSE) and executive function by the Digit Symbol Substitution Test (DSST). We used linear mixed models to estimate the mean decline and 95% confidence intervals (95% CI) for 3MSE and DSST scores by incident stroke and HAI status, adjusted for demographics and vascular risk factors.

Among 5,443 participants ≥65 years without previous history of stroke, 393 participants had stroke with HAI (SI), 766 had a stroke only (SO), and 4,284 had no stroke (NS) throughout a maximum 9-year follow-up. For 3MSE, compared with NS participants, SO participants had a similar adjusted mean decline (additional 0.08 points/year, 95% CI: -0.15, 0.31), while SI participants had a more rapid decline (additional 0.28 points/year, 95% CI: 0.16, 0.40). Adjusted mean decline was 0.20 points/year faster (95% CI: -0.05, 0.45) among SI than SO participants. For DSST, compared with NS participants, SO participants had a faster adjusted mean decline (additional 0.17 points/year [95% CI: 0.003, 0.33]), as did SI participants (additional 0.27 points/year [95% CI: 0.19, 0.35]).

Stroke, when accompanied by HAI, leads to a faster long-term decline in cognitive ability than in those without stroke. The clinical and public health implications of the effect of infection on post-stroke cognitive decline warrant further attention.