Results
Of the 1316 patients who were hospitalized with proven COVID-19 between 1th of March and 31st of May 2020, 239 patients were excluded because of reasons depicted in Figure 1. Of the 1154 patients included in this study, 92 (8%) used VKA and 98 (8%) used DOAC, and 964 (84%) patients did not use therapeutic anticoagulation prior to COVID-19 diagnosis. All patients in the exposed group were continued on therapeutic anticoagulation during hospitalization. Among patients who did not use therapeutic anticoagulation prior to admission, 856 (89%) received prophylactic LMWH during hospitalization. COVID-19 was confirmed by a positive PCR test in 1124 (97%) patients or considered confirmed by clinical features in combination with a CT scan with a very high level of suspicion (CO-RADS 5) in 30 (3%) patients.
Baseline patient characteristics are shown in table 1. Patients who used therapeutic anticoagulation prior to hospitalization were older, more likely of male sex, and more likely to have cardiovascular comorbidities or a no-ICU policy compared to patients who did not use prior therapeutic anticoagulation. Subsequent propensity score matching retained 164 (86%) patients who used prior therapeutic anticoagulation and 410 unexposed patients. The main covariates were balanced between the groups after the propensity score matching (table 1).
The results from the total cohort and the propensity score-matched analysis on the associations between therapeutic anticoagulation use and the dichotomous outcomes are presented in table 2A. In the crude total cohort analysis, therapeutic anticoagulation use was associated with an increased risk of mortality and decreased risks of ICU admission, mechanical ventilation, and PE. In the propensity score-matched analyses, however, no associations between therapeutic anticoagulation use and the outcomes were observed, except for a decreased risk of PE among patient with therapeutic anticoagulation (RR 0∙19 (95% CI 0∙05-0∙80)) (Table 2, supplementary Figure S2). In addition, therapeutic anticoagulation use was not associated with length of hospital stay (table 2B).
Similar to the primary analysis, no associations were found between VKA or DOAC use prior to admission and COVID-19 related clinical outcome parameters after propensity score matching (see tables S1-S6, in the online supplement).