Thread by @DrMattMcCarthy

Common #COVID question: When should we extend the duration of dexamethasone therapy? Dex is a steroid that has become a mainstay of treatment for hospitalized patients needing oxygen. After 10 days of treatment, some patients improve and no longer need the drug while others...

develop conditions (organizing pneumonia) that may benefit from a longer course of steroids. But there's a risk to extending the treatment. Dex can potentially compromise the immune system in a way that's harmful, making it more difficult to fight infection.

Severe #COVID19 is driven, at least in part, by the consequences of an exuberant inflammatory response. This is sometimes called cytokine storm, but that is overly reductive. It's really immune misfiring, and steroids like dexamethasone help suppress the aberrant response.

But it's not selective suppression. Dexamethasone squashes a variety of immune pathways, some of which may be actively fighting the virus. This presents a problem: We want to dampen the immune response, but not too much. How do we know when we've exceeded the limit?

For now, most patients get up to 10 days of dex and that's it. But a subset develop signs and symptoms that argue for a longer course. Sometimes we deviate, but the approach varies from patient to patient. A standardized approach is lacking. There must be a better way.

Serum interleukin-6 has been called (controversially) the best available biomarker for severity of #COVID and may be useful for guiding treatment of disease. Instead of relying on expert opinion to guide the duration of dex, we might turn to a blood test. thelancet.com/journals/lanre…

The problem is that the IL-6 biomarker isn't readily available and there's no evidence (yet) that it will actually help guide steroid use. Future research may unravel a better way. For now, 3 things are necessary: vital signs, a chest CT, and a conversation with a pulmonologist.

Takeaway: The immune system sometimes goes haywire but the line between normal and abnormal is often blurry & steroids can be both beneficial and harmful. For now, we're using dexamethasone for up to 10 days but that may change as we learn more about the immune response to COVID.