32. The COVID Mortality Score (VACO)
The Veterans Health Administration COVID-19 (VACO) Index for COVID-19 Mortality predicts 30 day mortality following a positive test. VACO co-creators Amy Justice MD, PhD and Joseph King Jr, MD, MSCE break down how to use VACO, what it does, and what it doesn’t. We’re also joined by emergency physician Joe Habboushe MD, CEO of MDCalc, whose online VACO calculator makes using VACO far easier than doing it in your head. Here is a link to the VACO Calculator.
The Veterans Health Administration COVID-19 (VACO) Index, what it is and how it helps us evaluate patients [01:20];
The VACO Index predicts the likelihood of death within 30 days of testing positive for COVID-19 given the patient’s age, gender and comorbidities.
It is not an acute risk score that takes into account the patient’s current condition.
The index has been internally and externally validated.
Why VACO doesn’t take into account race or BMI [03:40];
The study authors found that in their VA population, race did not have a differential effect on mortality after adjusting for comorbidities, age, and gender.
Many of the papers that talk about race being associated with bad outcomes concatenate testing and testing positive. They don't separate testing positive from dying.
While the PLOS study showed that black and Hispanic ethnicity has a two-fold increased risk of testing positive for COVID-19, in the VA population this does not translate to increased mortality. This may be due to lower barriers to care in VA patients which results in reduced severity of illness.
BMI was found to add too small a signal to the model that it didn’t make sense to include it. Furthermore, only a BMI >35 was found to make a significant difference.
Whether VACO can be useful in the ED or the acute setting [08:20];
The VACO Index can be helpful in directing follow-up in patients who undergo drive-up testing. While most who test positive are advised to stay home for 14 days, those whose VACO score predicts a poor outcome may benefit from closer follow-up by phone or in the clinic. Some would argue that a poor VACO score should prompt lab testing to see if their disease is going in the ‘wrong direction’.
The score does not help you differentiate mortality risk for patients with COVID-19 who are already hypoxic and sick. For these patients, as they get sicker, the score doesn’t change.
Potential applications of the VACO index [12:15];
Identifying and alerting patients who, based on pre-existing conditions, are so high risk that they should take extra precautions to avoid the potential for COVID exposure.
Guiding the need for follow-up when patients test positive.
Helping inform the clinical judgement process when health care systems are asked to prioritize vaccine distribution.
Providing a tool for lay people who are considering travel, so they understand the risk they might be taking.
Combatting vaccine hesitancy. People who are worried about vaccine side effects can weigh their concern over this with the predicted mortality risk if they or their loved one contracts COVID.
What VACO does not do [18:30];
VACO predicts short-term mortality. It does not predict long haulers, hospitalization, the need for ICU admission, etc.
It’s important to know that the VACO mortality numbers were developed early in the pandemic (up into April 15, 2020). Advances in COVID treatment likely make the absolute risk number in the calculator an overestimate of current mortality risk.
While the absolute risk estimate may fluctuate, VACO should be reliable with respect to identifying high vs. low risk people.
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Shownotes by Melissa Orman, MD
If you want to get into the granular details of this interview, below is the video recording of the full, unedited conversation.