An observational study of intermediate- or high-dose thromboprophylaxis for critically ill COVID-19 patients.

BACKGROUND: Critically ill COVID-19 patients have a high reported incidence of thromboembolic complications and the optimal dose of thromboprophylaxis is not yet determined. The aim of this study was to investigate if 90-day mortality differed between patients treated with intermediate- or high-dose thromboprophylaxis. METHOD: In this retrospective study, all critically ill COVID-19 patients admitted to intensive care from March 6th until July 15th, 2020, were eligible. Patients were categorized into groups according to daily dose of thromboprophylaxis. Dosing was based on local standardized recommendations, not on degree of critical illness or risk of thrombosis. Cox proportional hazards regression was used to estimate hazard ratios of death within 90 days from ICU admission. Multivariable models were adjusted for sex, age, body-mass index, Simplified Acute Physiology Score III, invasive respiratory support, glucocorticoids, and dosing strategy of thromboprophylaxis. RESULTS: A total of 165 patients were included; 92 intermediate- and 73 high-dose thromboprophylaxis. Baseline characteristics did not differ between groups. The 90-day mortality was 19.6% in patients with intermediate-dose and 19.2% in patients with high-dose thromboprophylaxis. Multivariable hazard ratio of death within 90 days was 0.74 (95% CI, 0.36-1.53) for the high-dose group compared to intermediate-dose group. Multivariable hazard ratio for thromboembolic events and bleedings within 28 days was 0.93 (95% CI 0.37-2.29) and 0.84 (95% CI 0.28-2.54) for high versus intermediate dose, respectively. CONCLUSIONS: A difference in 90-day mortality between intermediate- and high-dose thromboprophylaxis could neither be confirmed nor rejected due to a small sample size.

Dosing of thromboprophylaxis and mortality in critically ill COVID-19 patients.

BACKGROUND: A substantial proportion of critically ill COVID-19 patients develop thromboembolic complications, but it is unclear whether higher doses of thromboprophylaxis are associated with lower mortality rates. The purpose of the study was to evaluate the association between initial dosing strategy of thromboprophylaxis in critically ill COVID-19 patients and the risk of death, thromboembolism, and bleeding. METHOD: In this retrospective study, all critically ill COVID-19 patients admitted to two intensive care units in March and April 2020 were eligible. Patients were categorized into three groups according to initial daily dose of thromboprophylaxis: low (2500-4500 IU tinzaparin or 2500-5000 IU dalteparin), medium (> 4500 IU but < 175 IU/kilogram, kg, of body weight tinzaparin or > 5000 IU but < 200 IU/kg of body weight dalteparin), and high dose (≥ 175 IU/kg of body weight tinzaparin or ≥ 200 IU/kg of body weight dalteparin). Thromboprophylaxis dosage was based on local standardized recommendations, not on degree of critical illness or risk of thrombosis. Cox proportional hazards regression was used to estimate hazard ratios with corresponding 95% confidence intervals of death within 28 days from ICU admission. Multivariable models were adjusted for sex, age, body mass index, Simplified Acute Physiology Score III, invasive respiratory support, and initial dosing strategy of thromboprophylaxis. RESULTS: A total of 152 patients were included: 67 received low-, 48 medium-, and 37 high-dose thromboprophylaxis. Baseline characteristics did not differ between groups. For patients who received high-dose prophylaxis, mortality was lower (13.5%) compared to those who received medium dose (25.0%) or low dose (38.8%), p = 0.02. The hazard ratio of death was 0.33 (95% confidence intervals 0.13-0.87) among those who received high dose, and 0.88 (95% confidence intervals 0.43-1.83) among those who received medium dose, as compared to those who received low-dose thromboprophylaxis. There were fewer thromboembolic events in the high (2.7%) vs medium (18.8%) and low-dose thromboprophylaxis (17.9%) groups, p = 0.04. CONCLUSIONS: Among critically ill COVID-19 patients with respiratory failure, high-dose thromboprophylaxis was associated with a lower risk of death and a lower cumulative incidence of thromboembolic events compared with lower doses. TRIAL REGISTRATION: Clinicaltrials.gov NCT04412304 June 2, 2020, retrospectively registered.

[Rapid point-of-care serology testing for sars-cov-2]

Increasing evidence indicates immunity against severe acute respiratory syndrome coronavirus 2 (sars-cov-2) after covid-19, but it remains unclear for how long the protection remains. Serology testing seems to have a higher sensitivity than molecular diagnostics from 8 days after onset of symtoms, and should be part of risk assessment and epidemiological studies of COVID-19. The performance of commercial serological point-of-care (POC) lateral flow tests are highly manufacturer-dependant. Low sensitivity increases the risk of false negative results and could result in unnecessary quarantine of test persons with developed antibodies. Low specificity increases the risk of false positive results and could lead to false assumptions of immunity. Carefully selected serological POC tests for sars-cov-2 can be used in large scale testing but should only be used by licensed medical staff able to understand their limitations and interpret the results.