Coronavirus disease 2019 (COVID-19) was “robustly” associated with an increased risk of neurological and psychiatric disorders in the 6 months after a diagnosis, according to a study published in The Lancet Psychiatry. The study found that risks were greatest in, but not limited to, patients who had severe COVID-19.
“To our knowledge, we provide the first meaningful estimates of the risks of major neurological and psychiatric conditions in the 6 months after a COVID-19 diagnosis, using the electronic health records of over 236,000 patients with COVID-19,” wrote Maxime Taquet, University of Oxford, Oxford, United Kingdom, and colleagues. “We report their incidence and hazard ratios compared with patients who had had influenza or other respiratory tract infections.”
This retrospective cohort study and time-to-event analysis used data from the TriNetX electronic health records network, which includes more than 81 million patients, primarily in the US. The study’s primary cohort comprised 236,379 patients diagnosed with COVID-19, and two propensity-score matched control cohorts comprised 105,579 patients diagnosed with influenza and 236,038 patients diagnosed with any respiratory tract infection including influenza. Further, the COVID-19 cohort was divided into subgroups of patients who were not hospitalised (n = 190,077), those who were hospitalised (n = 46,302 patients), those who required intensive therapy unit (ITU) admission (n = 8,945), and those who received a diagnosis of encephalopathy (n = 6,229).
Overall, the estimated incidence of a neurological or psychiatric diagnosis in the 6 months following a COVID-19 diagnosis was 33.62% (95% confidence interval [CI] 33.17–34.07), with 12.84% (12.36–13.33) receiving their first such diagnosis.
The most common diagnoses after COVID-19 were anxiety disorders (17.39%), mood disorders (13.66%), substance misuse disorders (6.58%), and insomnia (5.42%). The incidence of neurological outcomes was lower, including 2.10% for ischaemic stroke, 0.67% for dementia, and 0.56% for intracranial haemorrhage.
Further, researchers found that severe COVID-19 was associated with a higher prevalence of neurologic or psychological disorders, whereby the estimated incidence of a diagnosis was 38.73% (95% CI 37.87–39.60) for patients who were hospitalised, 46.42% (44.78–48.09) for those admitted to ITU, and 62.34% (60.14–64.55) for those diagnosed with encephalopathy, compared with 31.74% (31.22–32.27) in patients who were not hospitalised. A similar, but more marked, increasing trend was also observed for patients receiving their first recorded neurological or psychiatric diagnosis.
As with incidences, hazard ratios (HRs) were observed to be higher in patients who had more severe COVID-19, whereby HRs were 1.58 (95% CI 1.50–1.67) for any diagnosis and 2.87 (2.45–3.35) for any first diagnosis among those admitted to ITU compared with those not admitted to ITU. Similarly, HRs for any diagnosis was 1.85 (1.73–1.98) and 3.19 (2.54–4.00) for any first diagnosis of neurologic or psychological disorders in patients with COVID-19 who had encephalopathy diagnosed during acute illness compared with patients who did not have encephalopathy. Meanwhile, patients with COVID-19 who were hospitalised were also at risk of a diagnosis of neurologic or psychological disorders than patients who were not hospitalised (HR 1.33, 95% CI 1.29–1.37, P<0.0001, for any diagnosis; 1.70, 1.56–1.86, P<0.0001, for first diagnosis).
Moreover, study data also revealed that most diagnostic categories were more common in patients who had COVID-19 than in those who had influenza (HR 1.44, 95% CI 1.40–1.47, P<0.0001, for any diagnosis; 1.78, 1.68–1.89, P<0.0001, for any first diagnosis) and those who had other respiratory tract infections (1.16, 1.14–1.17, P<0.0001, for any diagnosis; 1.32, 1.27–1.36, P<0.0001, for any first diagnosis).
Additionally, when the researchers compared cohorts of patients who had not required hospitalisation, the overall HR for any diagnosis of neurologic or psychological disorders was 1.47 (95% CI 1.44–1.51) for patients who had COVID-19 compared with patients who had influenza, and 1.16 (1.14–1.17) compared with those who had other respiratory tract infections. For a first diagnosis, the HRs were 1.83 (1.71–1.96) compared with patients who had influenza and 1.28 (1.23–1.33) compared with those who had other respiratory tract infections.
“We show that both incidence and hazard ratios were greater in patients who required hospitalisation or admission to the ITU, and in those who had encephalopathy (delirium and other altered mental states) during the illness compared with those who did not,” the authors noted.
“Our data provide important evidence indicating the scale and nature of services that might be required,” the authors added. “The findings also highlight the need for enhanced neurological follow-up of patients who were admitted to ITU or had encephalopathy during their COVID-19 illness.”