Mild Cognitive Disorder in Post-COVID-19 Syndrome: A Retrospective Cohort Study of 67,000 Primary Care Post-COVID Patients

BACKGROUND: Little is known about the impact of COVID-19 on mild cognitive disorder. OBJECTIVE: The aim of this retrospective cohort study was to investigate whether COVID-19 diagnosis is associated with subsequent mild cognitive disorder (MCD) compared to acute upper respiratory infections (AURI). METHODS: This retrospective cohort study used data from the Disease Analyzer database (IQVIA) and included 67,046 patients with first-time symptomatic or asymptomatic COVID-19 diagnoses in 1,172 general practices in Germany between March 2020 and September 2021. Diagnoses were based on ICD-10 codes. Patients diagnosed with AURI were matched to 67,046 patients with COVID-19 using propensity scores based on sex, age, index month, and comorbidities. The index date was the diagnosis date for either COVID-19 or AURI. Associations between the COVID-19 and MCD were studied using conditional Poisson regression models. RESULTS: The incidence of MCD was 7.6 cases per 1,000 person-years in the COVID-19 group and 5.1 cases per 1,000 person-years in the AURI group (IRR = 1.49, 95% CI = 1.22–1.82). The incidence rate ratio decreased strongly with increasing age from 10.08 (95% CI = 4.00–24.42) in the age group≤50 to 1.03 (95% CI = 0.81–1.31) in the age group > 70. In addition, the association between COVID-19 and MCD was significant in women (IRR: 1.70, 95% CI: 1.34–2.16) but not in men (IRR: 1.08, 95% CI: 0.75–1.56). CONCLUSION: The incidence of MCD was low but significantly higher in COVID-19 than in AURI patients, especially among younger patients. If a cognitive disorder is suspected, referral to a specialist is recommended.