A week ago Drs. Dan Erickson and Artin Massihi shared data from their regional urgent cares that seemed to indicate that SARS-CoV-2 had spread much further in their region than testing would indicate and that it was therefore much less dangerous than thought. They went so far as to say that the stay-at-home order is unnecessary and that people should get back to work.
“Do we need to still shelter in place? Our answer is no. Do we need businesses to be shut down? No. Do we need to test them and get them back to work? Yes we do,”
Dr. Dan Erickson.
The best critique I’ve seen of their study came from Dr. Carl T. Bergstrom, a University of Washington biologist who specializes in infectious disease modeling. Here’s a transcript of his response with a link to the actual series of tweets below.
“What they did was simple: they looked at the fraction of patients who tested positive for COVID-19 at the clinics they own. They found 340 out of 5213 tests were positive, about 6.6.%. They assume the same fraction of the whole population are infected. From there, they scale up to the state level and claim 12% incidence statewide. The news story says it is using the same calculation, but it can’t be–how did they get from 6.6% to 12%? Perhaps they estimating [sic] infected *ever* versus infected *currently*. It is not clear.
Using that 12% infected figure, and a known 1400 deaths in California, they assume 1400 out of 4.7 million have died. That gives them an infection fatality rate of 0.03%. That is they think that if 10,000 are infected, 3 will die on average. The problem with this approach is that during a pandemic, the people who come into an urgent care clinic are not a random sample of the population. A large fraction of them are coming in precisely because they suspect that they have the disease.
This generates sampling bias.
Estimating that fraction infected from patients at an urgent care facility is a bit like estimating the average height of Americans from the players on an NBA court. It’s not a random sample, and it gives a highly biased estimate.
Moreover the estimate does not pass even a basic plausibility check. In New York City, 12,067 people are known to have died from the virus, out of a population of 8.4 million. This is a rate of 0.14% of all people. Not just infected people. All people. That gives us a lower bound on the death rate in New York. Not an estimate, a lower bound. The death rate for infected people is obviously higher than 0.14% because not everyone in New York has been infected. And yet that 0.14% lower bound is nearly *five times as high* as the 0.03% that the Bakerfield [sic] duo are claiming. They’ve used absurd methodology to arrive at an implausible number.
If the pandemic were not so severely politicized, this would be a non-issue from the start.
Dr. Carl T. Bergstrom
The docs from Bakersfield made a common statistical error by not studying a random sample of the population. If you’re going to use sample data to draw conclusions about the total population, you’d better make sure your sample is representative of the total population. It’s easy to get wrong even if you’re trying hard to get it right. Had they utilized a tool (e.g. random digit dialing) to find representative members of their community and schedule that random sample of people for testing they’d have come a lot closer to creating an actual study. Instead, they injected an almost humorous level of bias into their study by choosing a sample certain to have a higher infection rate than the total population–quite a bit higher as they’re coming into an urgent care, you know, sick.
The American College of Emergency Physicians and the American Academy of Emergency Medicine weren’t laughing however when they issued a joint statement on the matter.
The American College of Emergency Physicians (ACEP) and the American Academy of Emergency Medicine (AAEM) jointly and emphatically condemn the recent opinions released by Dr. Daniel Erickson and Dr. Artin Massihi. These reckless and untested musings do not speak for medical societies and are inconsistent with current science and epidemiology regarding COVID-19. As owners of local urgent care clinics, it appears these two individuals are releasing biased, non-peer reviewed data to advance their personal financial interests without regard for the public’s health.
COVID-19 misinformation is widespread and dangerous. Members of ACEP and AAEM are first-hand witnesses to the human toll that COVID-19 is taking on our communities. ACEP and AAEM strongly advise against using any statements of Drs. Erickson and Massihi as a basis for policy and decision making.
AAEP/AAEM Joint Statement on Physician Misinformation
I’m going to give these two docs the benefit of the doubt and assume that they just made a huge mistake for which they are embarrassed. I’m going to assume that they weren’t actually trying to put their own financial wellbeing ahead of the public’s health. I’m going to assume they did not have a political agenda when crafting this mess of a study.
I think it’s important for my own peace of mind that I do that.
CHRIS DAEL 