Anticoagulant use before COVID-19 diagnosis prevent COVID-19 associated acute venous thromboembolism or not:A systematic review and meta-analysis

BACKGROUND Coagulopathy and thromboembolic events are associated with poor outcomes in coronavirus disease 2019(COVID-19)patients.There is conflicting evidence on the effects of chronic anticoagulation on mortality and severity of COVID-19 disease.AIM To summarize the body of evidence on the effects of pre-hospital anticoagulation on outcomes in COVID-19 patients.METHODS A Literature search was performed on LitCovid PubMed,WHO,and Scopus databases from inception(December 2019)till June 2023 for original studies reporting an association between prior use of anticoagulants and patient outcomes in adults with COVID-19.The primary outcome was the risk of thromboembolic events in COVID-19 patients taking anticoagulants.Secondary outcomes included COVID-19 disease severity,in terms of intensive care unit admission or invasive mechanical ventilation/intubation requirement in patients hospitalized with COVID-19 infection,and mortality.The random effects models were used to calculate crude and adjusted odds ratios(aORs)with 95%confidence intervals(95%CIs).RESULTS Forty-six observational studies met our inclusion criteria.The unadjusted analysis found no association between prior anticoagulation and thromboembolic event risk[n=43851,9 studies,odds ratio(OR)=0.67(0.22,2.07);P=0.49;I2=95%].The association between prior anticoagulation and disease severity was non-significant[n=186782;22 studies,OR=1.08(0.78,1.49);P=0.64;I2=89%].However,pre-hospital anticoagulation significantly increased all-cause mortality risk[n=207292;35 studies,OR=1.72(1.37,2.17);P<0.00001;I2=93%].Pooling adjusted estimates revealed a statistically non-significant association between pre-hospital anticoagulation and thromboembolic event risk[aOR=0.87(0.42,1.80);P=0.71],mortality[aOR=0.94(0.84,1.05);P=0.31],and disease severity[aOR=0.96(0.72,1.26);P=0.76].CONCLUSION Prehospital anticoagulation was not significantly associated with reduced risk of thromboembolic events,improved survival,and lower disease severity in COVID-19 patients.

Association of latitude and altitude with adverse outcomes in patients with COVID-19: The VIRUS registry

BACKGROUND The coronavirus disease 2019(COVID-19)course may be affected by environmental factors.Ecological studies previously suggested a link between climatological factors and COVID-19 fatality rates.However,individual-level impact of these factors has not been thoroughly evaluated yet.AIM To study the association of climatological factors related to patient location with unfavorable outcomes in patients.METHODS In this observational analysis of the Society of Critical Care Medicine Discovery Viral Infection and Respiratory Illness Universal Study:COVID-19 Registry cohort,the latitudes and altitudes of hospitals were examined as a covariate for mortality within 28 d of admission and the length of hospital stay.Adjusting for baseline parameters and admission date,multivariable regression modeling was utilized.Generalized estimating equations were used to fit the models.RESULTS Twenty-two thousand one hundred eight patients from over 20 countries were evaluated.The median age was 62(interquartile range:49-74)years,and 54%of the included patients were males.The median age increased with increasing latitude as well as the frequency of comorbidities.Contrarily,the percentage of comorbidities was lower in elevated altitudes.Mortality within 28 d of hospital admission was found to be 25%.The median hospital-free days among all included patients was 20 d.Despite the significant linear relationship between mortality and hospital-free days(adjusted odds ratio(aOR)=1.39(1.04,1.86),P=0.025 for mortality within 28 d of admission;aOR=-1.47(-2.60,-0.33),P=0.011 for hospital-free days),suggesting that adverse patient outcomes were more common in locations further away from the Equator;the results were no longer significant when adjusted for baseline differences(aOR=1.32(1.00,1.74),P=0.051 for 28-day mortality;aOR=-1.07(-2.13,-0.01),P=0.050 for hospital-free days).When we looked at the altitude’s effect,we discovered that it demonstrated a non-linear association with mortality within 28 d of hospital admission(aOR=0.96(0.62,1.47),1.04(0.92,1.19),0.49(0.22,0.90),and 0.51(0.27,0.98),for the altitude points of 75 MASL,125 MASL,400 MASL,and 600 MASL,in comparison to the reference altitude of 148 m.a.s.l,respectively.P=0.001).We detected an association between latitude and 28-day mortality as well as hospital-free days in this worldwide study.When the baseline features were taken into account,however,this did not stay significant.CONCLUSION Our findings suggest that differences observed in previous epidemiological studies may be due to ecological fallacy rather than implying a causal relationship at the patient level.