Dissipating the fog: Cognitive trajectories and risk factors 1 year after COVID‐19 hospitalization

Introduction Cognitive impairment is common after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, associations between post-hospital discharge risk factors and cognitive trajectories have not been explored. Methods A total of 1105 adults (mean age ± SD 64.9 ± 9.9 years, 44% women, 63% White) with severe coronavirus disease 2019 (COVID-19) were evaluated for cognitive function 1 year after hospital discharge. Scores from cognitive tests were harmonized, and clusters of cognitive impairment were defined using sequential analysis. Results Three groups of cognitive trajectories were observed during the follow-up: no cognitive impairment, initial short-term cognitive impairment, and long-term cognitive impairment. Predictors of cognitive decline after COVID-19 were older age (β = −0.013, 95% CI = −0.023;−0.003), female sex (β = −0.230, 95% CI = −0.413;−0.047), previous dementia diagnosis or substantial memory complaints (β = −0.606, 95% CI = −0.877;−0.335), frailty before hospitalization (β = −0.191, 95% CI = −0.264;−0.119), higher platelet count (β = −0.101, 95% CI = −0.185;−0.018), and delirium (β = −0.483, 95% CI = −0.724;−0.244). Post-discharge predictors included hospital readmissions and frailty. Discussion Cognitive impairment was common and the patterns of cognitive trajectories depended on sociodemographic, in-hospital, and post-hospitalization predictors. Highlights Cognitive impairment after coronavirus disease 2019 (COVID-19) hospital discharge was associated with higher age, less education, delirium during hospitalization, a higher number of hospitalizations post discharge, and frailty before and after hospitalization. Frequent cognitive evaluations for 12-month post-COVID-19 hospitalization showed three possible cognitive trajectories: no cognitive impairment, initial short-term impairment, and long-term impairment. This study highlights the importance of frequent cognitive testing to determine patterns of COVID-19 cognitive impairment, given the high frequency of incident cognitive impairment 1 year after hospitalization.