(303) Antithrombotic use decreases the risk of mortality due to COVID-19 of nursing home residents during the first wave

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Background: During the initial period of the COVID-19 pandemic, various studies showed that the risk of thrombotic complications was high in COVID-19 patients. Nursing home residents (NHRs), the most severely affected group worldwide, showed a high mortality rate during that initial period. Anticoagulants were associated with a favorable prognosis in hospitalized patients from a general population. However, there is currently very little data available on NHRs and it is unknown whether results would be similar for this often-frail population.

Objectives: The aim of this study was to investigate the effect of antithrombotic and antiplatelet medication at baseline for other indications in NHRs with COVID-19 on all-cause 30-day mortality.

Methods: A retrospective cohort study using routine care data, the electronic health records (EHR), from the information systems of NHRs and data collected as part of national COVID-19 registration policy. This data was linked to pharmacy data on medication use. Exposure was defined as preexistent anticoagulation, i.e., LMWH in therapeutic dosage, vitamin K antagonists, or DOACs (both full and reduced dose) and antiplatelet therapy in the last 30 days before start of COVID-19 infection. The primary outcome was all-cause mortality in NHRs during 30 days of follow-up after diagnosis of COVID-19. Univariable and multivariable logistic regression was performed. Co-variates which were significant with a P-value < 0.10 were included in the multivariable analysis. All analyses were performed in SPSS and R (R Foundation for Statistical Computing, Vienna, Austria; https://www.R-project.org) with the appropriate packages.

Results: We included 3394 adult patients with a confirmed diagnosis of COVID-19 based on a positive RT-PCR for SARS-CoV-2 or with a clear clinical suspicion of COVID-19. In the univariable analysis COVID-19 NHRs with anticoagulant use at baseline and NHRs with antiplatelet use only at baseline showed a decreased mortality, OR: 0.82 (CI: 0.67–1.00) and OR: 0.96 (CI: 0.80–1.14), respectively. In the multivariable analysis including the covariates age, gender, dementia, cardiovascular disease, M. Parkinson, type of department, anticoagulant use, and antiplatelet therapy decreased mortality, OR: 0.62 (CI: 0.48–0.82) and 0.80 (0.64–0.99), respectively.

Conclusions: In the first COVID-19 wave anticoagulant and antiplatelet use were associated with a reduced risk of mortality in NHRs. It is interesting whether these results remain similar in subsequent COVID-19 waves with more patients vaccinated and other COVID-19 variants.