Ninety-six patients with severe COVID-19 who survived intensive care unit (ICU) admission were enrolled in this prospective longitudinal cohort study. They either received no immunotherapy (n = 28) or were treated with dexamethasone or dexamethasone and tocilizumab (n = 68). Blood was sampled consecutively for 28 days during ICU stay, and inflammatory cytokines (IL-6, IL-8, IL-10, TNF, IP-10, MCP-1, IL-1RA, CRP) and neurofilament light chain (NfL) were assayed. Cytokine concentrations were the highest on ICU admission, but subsequently declined. Conversely, NfL concentrations increased 10-fold during ICU stay overall. Patients receiving dexamethasone had lower levels of NfL 14 days after admission compared to the ones without immunosuppressive treatment. Age, renal function, immunomodulatory treatment, high CRP, and high IL-8, TNF, and IL-1RA at day 14 were significant predictors of blood NfL levels at day 14 after admission. 27% of patients exhibited cognitive impairment 6 months after discharge from ICU. Patients with high NfL at day 14 were more likely to develop cognitive impairment 6 months after discharge at tests measuring processing speed (TMT-A and LDST) but not at tests measuring global cognition (MoCA) or working memory (Digit Span). The incidence of cognitive impairment did not differ between treatment groups.
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Observational study: prospective longitudinal cohort