NIH guidelines on anticoagulation in COVID-19; research on statin use, omicron variant

The NIH updated its treatment guidelines on Jan. 5 to address anticoagulation in hospitalized patients with COVID-19. At a minimum, the panel said, hospitalized COVID-19 patients should receive prophylactic doses of anticoagulants, such as low-molecular-weight heparin or unfractionated heparin, for as long as they are hospitalized. Specific recommendations for hospitalized patients requiring low-flow oxygen, hospitalized patients receiving ICU-level care, and hospitalized pregnant adults are online.

Statin treatment was not associated with improved outcomes in patients with COVID-19 admitted to the ICU, a study published Jan. 7 by The BMJ found. Researchers at 11 hospitals in Iran compared 290 adults randomly assigned to receive atorvastatin, 20 mg once daily, with 297 adults assigned to receive placebo. The study drug was continued 30 days after randomization, even if the patient was discharged from the hospital. The primary efficacy outcome was a composite of venous or arterial thrombosis, treatment with extracorporeal membrane oxygenation, or all-cause 30-day mortality. Sobhan Darou provided atorvastatin and matching placebo but did not fund the study. Patients' median age was 57 years, and 44% were women. Ninety-five patients (33%) in the atorvastatin group and 108 (36%) in the placebo group experienced The primary outcome not significantly different between groups (33% with atorvastatin vs. 36% with placebo; odds ratio, 0.84 [95% CI, 0.58 to 1.21]), nor was mortality (31% vs. 35%, respectively; odds ratio, 0.84 [95% CI, 0.58 to 1.22]). Rates of venous thromboembolism were 2% and 3%, respectively (odds ratio, 0.71; 95% CI, 0.24 to 2.06), and five patients in the atorvastatin group and six in the placebo group had elevated liver enzyme levels (3% vs. 2%; odds ratio, 0.85 [95% CI, 0.25 to 2.81]). The authors concluded that atorvastatin was not associated with a significant reduction in the composite outcome of venous or arterial thrombosis, treatment with extracorporeal membrane oxygenation, or all-cause mortality versus placebo in adults with COVID-19 who were admitted to the ICU.

A study published as a research letter in JAMA on Dec. 30 compared characteristics and outcomes of patients hospitalized in South Africa during the COVID-19 omicron wave versus previous waves caused by other variants. Researchers from a private health care group including 49 acute care hospitals looked at hospitalizations during wave 1 (June 14 to July 6, 2020), wave 2 (Dec. 1 to 23, 2020), and wave 3 (June 1 to 23, 2021) and compared them with those that occurred during the fourth wave (Nov. 15 to Dec. 7, 2021). All patients hospitalized with a positive COVID-19 test were included, and follow-up was through Dec. 20, 2021. During the first three waves, 68% to 69% of patients who presented to the ED with a positive COVID-19 test result were admitted, compared with 41.3% in wave 4. Patients admitted during wave 4 were younger (median age of 36 years compared to 59 years in wave 3, which had the highest median age of the first three waves; P<0.001) and were more likely to be women. Patients who were admitted in wave 4 were less likely to have comorbid conditions and less likely to present with an acute respiratory condition (31.6% in wave 4 vs. a maximum of 91.2% in wave 3; P<0.001). Most of the 971 patients admitted in wave 4 (66.4%) were unvaccinated. Patients in wave 4 were less likely to require oxygen therapy or mechanical ventilation and were less likely to be admitted to the ICU. The median length of stay was between seven and eight days in previous waves but decreased to three days in wave 4. Mortality rates were 19.7% in wave 1, 25.5% in wave 2, 29.1% in wave 3, and 2.7% in wave 4. The authors said more research is needed to determine whether the differences seen between waves were due in part to pre-existing acquired or natural immunity or whether omicron might be less pathogenic than previous variants.

In other research on omicron, three research letters published by the New England Journal of Medicine offered evidence on the effectiveness of vaccination against the variant. One letter, published Dec. 30, found that patients who had had COVID-19 and were then vaccinated and those who had received three doses of an mRNA vaccine had substantial neutralizing titers against omicron but that those who were unvaccinated or had received two doses of an mRNA vaccine did not. A second letter from Israel, published Dec. 29, found that three doses of the Pfizer-BioNTech vaccine offered better neutralization of beta, delta, and omicron versus two doses, but neutralization against omicron was lower by a factor of 4 than against the delta variant. Similarly, the third letter, from South Africa, also published Dec. 29, found that two doses of the Pfizer-BioNTech vaccine appeared to offer reduced protection against hospital admission for infections presumed to be caused by the omicron variant (70% effective) versus the delta variant (93% effective).