Chiefs’ Inquiry Corner – 10/25/2021

October 26, 2021

Chief residents of the NYU Langone Internal Medicine Residency give quick-and-easy, evidence-based answers to interesting questions posed by house staff, both in their clinics and on the wards.

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  The high-dose quadrivalent vaccine contains four times the antigen compared to standard inactivated flu vaccines. While the CDC has not expressed preference for any particular flu vaccine for people 65+, the high dose vaccine was FDA approved in 2019 for adults 65+ as studies such a 2014 NEJM RCT showed that adults 65+ had significantly higher antibody responses and the vaccine was 24% more effective in preventing the flu than the standard vaccine. Additionally a Lancet study in 2017 found that people 65+ who got the high-dose had a lower risk of hospital admission.

References: Comparative effectiveness of high-dose versus standard-dose influenza vaccination on numbers of US nursing home residents admitted to hospital: a cluster-randomised trial.

References: Efficacy of high-dose versus standard-dose influenza vaccine in older adults.
  D-dimer testing is frequently used in combination with clinical prediction scores to rule out pulmonary embolism among patients with a low pretest probability of embolism without using invasive, costly testing. Although the increased thrombotic risk seen in patients hospitalized with COVID-19 infection is now well-established, and thus the utility of D-dimer testing in this population for the purposes of excluding pulmonary embolism is likely nonexistent, early studies had inconsistent findings, and data was overall limited. A recent retrospective, cross-sectional study of consecutively hospitalized patients with COVID-19 infection at a single hospital examined D-dimer distributions among patients with and without PEs. Of the 287 patients that underwent CTPA for suspected pulmonary embolism, 37 patients (12.9%) had radiographic evidence of PE and 250 patients did not (87.1%). However, nearly all of the patients with and without PE had elevated d-dimer levels (92.3% and 91.2%, respectively), indicating that for people hospitalized with COVID-19 infection, the high pretest probability and poor specificity observed suggests that using d-dimer levels to exclude PE in this patient population is inappropriate.

References: D-Dimer Testing for the Exclusion of Pulmonary Embolism Among Hospitalized Patients With COVID-19
 Iron replacement therapy is indicated for iron-deficiency anemia and should not be delayed while performing etiologic workup, unless colonoscopy is to be imminently performed. There are a variety of oral formulations available over the counter (including ferrous gluconate, ferrous sulfate, and polysaccharide iron complex), all of which are similarly efficacious and have similar side effects (most often gastrointestinal upset and constipation). Regardless of preparation chosen, one dose should be taken either daily or every other day- every other day dosing has similar, or even improved, iron absorption, potentially with fewer side effects, but daily dosing may be preferable to promote ease of use and adherence. A good response to iron replacement therapy is a hemoglobin rise of at least 1g/dL within 2 weeks. Patients should be monitored in the first four weeks for hemoglobin response to oral iron, and treatment should be continued for about three months after normalization of the hemoglobin level. After restoration of hemoglobin and iron stores with iron replacement therapy, blood count should be monitored periodically (e.g., every six months initially) to detect recurrent iron deficiency anemia. Note that parenteral iron should be considered when oral is contraindicated, ineffective, or not tolerated, or if correction of iron-deficiency anemia is urgent.

References:  British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults.