Shop Talk is a newsletter published by The Evidence Workshop, LLC.
It helps clinicians integrate the best, available research evidence into front-line practice.
It’s high time for some good news, which is why we’re reporting on a recent finding suggesting that dexamethasone reduces death in people with COVID-19. Our goal is to leverage this upbeat story to lure you into appreciating the concept of number needed to treat (NNT).
Dexamethasone for COVID-19
On June 16, 2020 researchers from University of Oxford issued a press release indicating that dexamethasone reduces death in patients with COVID-19. The study has not been published in a scientific journal. But a committee overseeing the randomized controlled trial determined that enrollment was sufficient to establish benefit. Investigators indicated that dexamethasone should become a standard of care for patients with COVID-19. Conclusions were drawn in part from NNT.
NNT is the number of people you must treat to prevent 1 bad outcome.
A bad outcome is anything we would rather not have happen, e.g. an illness, injury, fall, or flair-up.
In the Oxford dexamethasone study, the bad outcome was death due to COVID-19.
The question researchers posed was, “How many patients must be treated with dexamethasone to prevent 1 death due to COVID-19?” The answer was 8 for patients who were ventilated and 25 for patients requiring oxygen.
What does NNT mean?
These values mean that if you use dexamethasone to treat 8 ventilated patients with COVID-19, you will prevent 1 death. You can also prevent 1 death if you use dexamethasone to treat 25 COVID-19 patients receiving oxygen.
Of interest, dexamethasone did not reduce deaths in individuals not receiving respiratory intervention. Thankfully, this group had a lower baseline risk of death than the other two groups. Without dexamethasone, the 28-day mortality from COVID-19 was 41% for patients who needed ventilation, 25% for those needing oxygen, and 13% for those who required neither ventilation nor oxygen.
How can I learn more?
You can read the full press release at http://www.ox.ac.uk/news/2020-06-16-low-cost-dexamethasone-reduces-death-one-third-hospitalised-patients-severe.
For information about NNT (including calculations), visit to the Oxford Center for Evidence Based Medicine at https://www.cebm.net/2014/03/number-needed-to-treat-nnt/.