Delirium Incidence and Predictors in SARS-CoV-2 Vaccinated Residents in Long-Term Care Facilities (LTCF): Insights from the GeroCovid Vax Study

Objective: SARS-CoV-2 vaccination can bring an important benefit for older people in terms of reduction of mortality and hospitalization; however, reports of rare adverse effects like altered consciousness and delirium among this demographic have raised concerns. This study aimed to assess delirium incidence post-SARS-CoV-2 vaccination and its predictors in older residents across 60 Italian long-term care facilities (LTCFs).

Design: This is a prospective cohort study considering data from GeroCovid Vax, a multicenter cohort study jointly performed by the Italian Society of Gerontology and Geriatrics (SIGG) (Florence, Italy) and the Italian National Institute of Health (Istituto Superiore di Sanità-ISS, Rome, Italy), and sponsored by the Italian Medicines Agency (Agenzia Italiana del Farmaco-AIFA).

Setting and participants: GeroCovid Vax enrolled LTCFs residents aged ≥60 who received at least 1 anti-SARS-CoV-2 vaccine dose.

Methods: Baseline data covered sociodemographic details, chronic diseases, medications, nutritional status, cognitive and functional assessments, mobility, and frailty. Delirium was assessed post-first, second, and booster vaccine doses using DSM-5 criteria. Data analysis involved descriptive statistics, multivariate logistic regression, and network analysis.

Results: A total of 2521 participants (mean age 83.10 ± 9.21 years, 70.7% female) were analyzed. Delirium incidence post-first, second, and booster doses was 3.5%, 1.6%, and 1.5%, respectively. Age, preexisting cognitive disorders, and frailty were significant predictors of delirium, with odds ratios (ORs) of 1.70 (95% CI, 1.08-2.77), 2.05 (95% CI, 1.40-2.97), and 1.77 (95% CI, 1.25-2.52), respectively. Prior use of antipsychotics (OR, 1.75; 95% CI, 1.22-2.51) and antidepressants (OR, 1.77; 95% CI, 1.25-2.52) correlated significantly with delirium. Network analysis indicated a strong association between anorexia and delirium.

Conclusion and implications: Post-vaccination delirium is infrequent and decreases with subsequent doses. Timely assessments for frailty and cognitive impairment could aid in stratifying delirium risk among LTCF residents, facilitating enhanced prevention measures and close monitoring for delirium indicators.