How Doctors Diagnose Things (An Explanation of COVID-19 Testing Criteria)

Image credit:

I’m going to pause in my evaluation of the Medicare for All Act of 2019 just for a week to write as a physician for once rather than as a health policy researcher. And not to talk about coronavirus (SARS-CoV-2) so much as to explain a principle of clinical medicine I wish more people would understand, especially now when it’s particularly relevant.

Let me explain to you how doctors diagnose things.

Any diagnostic effort a physician does starts with making a list of possible causes of the patient’s problem. That list is called a “differential diagnosis,” or a “differential,” for short. Only when you have determined your differential can you make decisions about how to proceed working up or treating a problem.

Together, the likelihood of all those things on the differential add up to 100%. If one of those things goes up in likelihood (say, because of a positive test for that thing), by definition the other things on the differential go down in likelihood.

So, for example, the patient I saw today. She hadn’t traveled anywhere recently, she hasn’t been exposed to anyone with COVID-19, and she doesn’t live in an area where there are many COVID-19 cases–all in all, she was very low risk for having COVID-19. But some food she ate yesterday didn’t sit well, and she vomited but also tried to take a breath at the same time. That didn’t work out so well, and she was trying to cough the vomit out of her lungs after that. About a day later, she was still coughing and short of breath, but now she was having fevers. COVID-19 was on the differential (cough, shortness of breath, fever), but bacterial pneumonia secondary to aspiration was much more likely. Did we need to test this lady?

With the information I’ve given you, the answer is probably no. We are pretty certain her symptoms were from that aspiration event, which makes COVID-19 very unlikely.

But some patients with that same story would still get tested (which was the case with this patient), as I’ll explain using the principle of a “testing threshold.”

Every item on the differential diagnosis sits somewhere on the probability spectrum in between 0% and 100%. If you test for the disease, and the test comes back negative, it pushes that one down closer to 0%. (How far it pushes it toward 0% depends on how reliable the test is.) And if the likelihood of something on the differential is close enough to 0%, then you say it’s unlikely enough that you can essentially think of it as being ruled out.

How close is “close enough to 0%”? Or, in other words, how unlikely does something have to be before we don’t feel the need to test for it further? Or, in other other words, how do we decide where to set that testing threshold? That depends on a few things, especially how risky it is to miss the diagnosis. If we’re dealing with the patient above, and I told you she’s a 25 year old with no medical problems and she works from her computer at home, it’s not very risky to miss the diagnosis, and we’d counsel her to make sure she’s isolated until a few days after all her symptoms have resolved. But if that patient is 80 years old and has severe COPD, this is an incredibly high risk individual, and missing a COVID-19 diagnosis, unlikely as it is, would be catastrophic, so we would definitely test her.

Similarly, young healthy healthcare providers are considered high risk because of the potential consequences of missing that diagnosis in them. The consequences are not to them directly, but rather the consequences are to their patients they could potentially spread it to, many of whom are likely elderly or high risk in other ways. Therefore, healthcare workers’ testing threshold is also set very low.

So, if you have symptoms, check testing criteria. Call a hotline. They will ask you questions to figure out where your testing threshold is, and based on that they will decide if you need to get tested or not.

Evaluating Sanders’s Medicare for All Act of 2019, Part 1

This is a 7-part series. Here are all the links: Part 2, Part 3, Part 4, Part 5, Part 6, Part 7.

I spent a lot of time looking at Senator Warren’s plans for Medicare for All (M4A) because she committed to a lot of details on her official campaign website. Senator Sanders, on the other hand, had very little. But he did commit to many details in his Medicare for All Act of 2019.

Bear in mind, this is him working as a senator–not as a president–so it’s hard to know how much this represents what he would push for as president, although I suspect it would change very little. And, at the time of this writing, it’s looking less and less likely that he will become the democratic presidential nominee, so maybe this is all moot. However, you may have noticed that M4A is becoming a bigger conversation every year, and people who once said it’s impossible are starting to rethink their assessments, so I’m going to move forward with evaluating this proposal anyway because I believe considering different possible implementations of a single-payer system in the US will become increasingly important to getting it right if it is in fact going to happen.

Let me also give you a reminder about my approach to these things. I’m biased, as everyone is, but even if you’ve read my writings for a while, you probably still do not know where I fall on many issues. This is on purpose. Maybe its my apolitical Canadian upbringing, but I feel strongly that people should reserve judgment on any issue until they have a good grasp of both sides. In these posts, I am neither arguing for or against M4A; I am simply trying to supply some of those pros and cons of different proposed implementations.

Having said all that, one bias I am upfront about is that I believe markets work. Put more precisely, I fall on the decentralized side of the economic spectrum,which, as a reminder, is independent of the welfare spectrum.

Now, on to my evaluation of the Medicare for All Act of 2019 (hereafter referred to as the Act). It has 11 titles, so let’s go through them one by one to see what kind of fun they contain. I’ll be focusing on the main details that will determine the overall structure of the system and how the healthcare system is likely to function.

Title I

This is the general stuff. Every resident and, from what I can tell, every non-resident too, will get benefits and be auto-enrolled and receive a Medicare card, at which point they will have the freedom to see any qualified healthcare provider. The only people who will not receive benefits will be those who are coming to the U.S. specifically to freeload off the free benefits.

Until the Act takes effect, people can continue any current health insurance. But, after that, no one will be allowed to sell coverage that duplicates the benefits provided under M4A. That doesn’t mean they can’t sell supplemental benefit plans though.

There will certainly be arguments about who should be covered by M4A, and, unsurprisingly, this falls on the “cover basically everyone” side of the spectrum. There are other options. I’m not an immigration expert, but it looks like there are four main immigration statuses in the U.S.: citizen, permanent or conditional resident, non-immigrants (because they’re only here temporarily with a visa), and undocumented. It might be easier to only send Medicare cards to citizens and residents. But, from the provider side, it sure would be nice to just treat everyone who walks in the door without regard to their immigration status. There’s also a charity aspect to consider here–how do we care for these people who are undocumented? I have a hard time with this because I want to provide compassion and improve others’ lives, but I also don’t want to reward illegal behaviors with free health insurance at the cost of taxpayers.

Straight up getting rid of employer-sponsored insurance is a great move and will enhance simplicity so much in the healthcare system and in the tax code, plus it will enhance job portability. Insurance should never have been paired with employment anyway–it was just an accident of historical policies.

Ok I’ll leave off right there for this week. If anyone has a strong argument one way or the other about covering undocumented people with M4A, please share below.

Continue to Part 2.

Price Transparency, In as Few Words as Possible

I’m ready to move on from everything being about coronavirus (although the memes have been very entertaining), so let’s talk more about price transparency this week. After that, as requested by a reader, I’ll spend some time looking at Senator Sanders’s Medicare for All Act of 2019 to get more details about what flavor of M4A he would push for as president (since, if you recall, his official campaign website details were pretty scant).

Months ago, I read this interesting Vox article about President Trump’s healthcare price transparency efforts. They asked a number of experts what they thought the results would be of these policies.

Let me summarize what they said:

  • Consumers will start shopping for and finding lower prices
  • High-priced providers will be shamed into lowering their prices
  • Policy makers would see how high prices actually are and would be more motivated to enact policies to reduce them
  • People still wouldn’t shop for healthcare services even with price information because (1) they can’t during emergencies, (2) they will often hit their deductible and therefore not end up paying more for more expensive providers anyway, and (3) patients will continue to go to the same providers even if they’re more expensive because they’ve already established a relationship with them
  • Price information will only be actionable when it’s in an easy-to-understand consumer interface plus paired with insurance benefit design changes
  • Without being paired with quality information, people might incorrectly assume the expensive providers are higher quality
  • Providers could see the prices insurers are paying other providers and demand they get those higher prices as well

All of those predictions are, to various degrees and in certain situations, likely to come true. But they don’t tell the whole story.

What would I say, in as few words as possible?

Price transparency, by itself, will only remove one of many barriers to people making price-sensitive decisions in healthcare–other barriers will remain, especially insurance plan designs that negate price differentials between providers via their cost-sharing requirements for patients. But, in the big picture, getting more price-sensitive decisions in healthcare is not the goal. The goal is to get as many purchase decisions as possible to become value sensitive, which requires knowledge of both price and quality. Only when patients start making value-sensitive decisions will higher-value providers start to win market share and enhanced profitability, thus stimulating innovation toward greater value over time. So while the short-term observable benefits of a price transparency policy will be minimal, it is one of many essential steps toward fixing incentives and improving value in our healthcare system.

Maybe that wouldn’t be short enough to be quotable, so instead they’d just say they asked Dr. Taylor Christensen, who said, “the short-term observable benefits of a price transparency policy will be minimal.”

Who Likes Coronavirus, Insurers or Providers?

face mask on blue background
Photo by Anna Shvets on

We’re in the midst of the coronavirus hype, and I think this provides a great opportunity to review incentives in the healthcare system. How do providers and insurers feel about this new pandemic?

Insurers are hating it. They are going to have a big bump in the number of people going to doctors and hospitals, which means they are paying a lot more money to providers in 2020 than they had anticipated. Insurer profits are going to tank. They would rather people be healthy–that’s how they are able to keep more money as profit. This is why I say that insurers’ only job is not to provide risk pooling, but also they are motivated to increase cost-saving prevention.

Providers are loving it. Hospital beds and emergency departments and urgent cares are all going to be full, which means profits will soar. Sure, salaried providers (me) and also providers paid per shift aren’t actually too happy about seeing more patients for no extra money, but the hospital administrators are all looking forward to large quarterly bonuses.

jobs and parties

And just as a little bonus to help you sound smart, let’s get some coronavirus terms straight (since it seems most media outlets can’t!) . . .

Coronavirus is a little family of viruses. There are four of them that commonly cause infections in humans, and I see them all the time because they’re one of the types of viruses that often cause upper respiratory tract infections (i.e., “the common cold”).

Every once in a while, another member of the coronavirus family figures out how to infect humans. The most famous one is what caused the whole SARS excitement in 2003. SARS stands for severe acute respiratory syndrome, because that’s the type of infection it caused. So they decided to name that member of the coronavirus family SARS-CoV (CoV, if you didn’t figure it out already, comes from coronavirus). I guess once a virus starts infecting humans, it’s worthy of receiving a new and improved name.

And now, in 2019, another one figured out how to infect humans. It causes a respiratory infection similar to the 2003 one, so they cleverly decided to name this new virus SARS-CoV-2.

Fix this in your brain. The virus is called SARS-CoV-2. Honestly, though, you can just refer to it as “coronavirus” because I’m pretty sure people will know which member of the family you’re talking about.

The disease SARS-CoV-2 causes, however, has its own name: coronavirus disease (#inspired). But, for short, they call it COVID-19 (because it started in 2019).

So, when you are talking about the virus, call it SARS-CoV-2, or, less precisely, coronavirus. And when you’re talking about the respiratory disease that virus causes, you should be saying COVID-19, or coronavirus disease.

Why Providers Don’t Innovate

The last couple weeks, I’ve been writing about how innovation can solve our healthcare spending problem and why it’s not happening. Last week, I gave some thoughts on why insurers don’t innovate. This week, let’s talk about providers.

One of my favorite examples that illustrates some of the challenges providers face when they try to innovate is detailed in the book Transforming Health Care: Virginia Mason Medical Center’s Pursuit of the Perfect Patient Experience. It talks about how they noticed that a lot of patients were presenting with low back pain and were not getting optimal treatment, so they decided to do something about it. They completely redesigned their low back pain care pathway, cutting out all the unnecessary things and getting patients the beneficial things much quicker. They started getting patients back to work way sooner, and things were going great, except for one problem: by cutting out unnecessary MRIs for uncomplicated cases, they were losing a lot of profit.

This happens a lot. Providers figure out how to deliver better care for patients, and then profitability suffers.

The solution for this specific issue is known. What if people, rather than buying a whole bunch of individual services that they hope will add up to a solution to their back pain, paid for a single product? They could buy the descriptively named “back pain fix.” This back pain fix product would include whatever was necessary (all the office visits, PT appointments, etc.) to get their backs feeling better. Then, when a healthcare system innovates and cuts out unnecessary services, they are keeping extra money in their pocket, so profitability actually improves!

This would be amazing, except for another problem that would arise. If only one insurer agrees to pay Virginia Mason for this “back pain fix” and the rest keep paying the traditional way, then they’re still losing money when treating patients with traditional-pay insurers. The lesson here is that not only do we need to pay for specific definable solutions to patients’ problems (often called “bundles”), but we also need to get all insurers to agree to start doing that at the same time.

This, by the way, is a problem I see over and over with provider innovations. Think about patient-centered medical homes. The doctor’s office usually needs to hire some sort of nurse coordinator who can be reaching out to patients to make sure they’re taking their medications and such, and this nurse’s salary is paid for by the “per-member-per-month” fee that insurers pay to doctor’s offices that are running medical homes. But when you only have 40% of your patients on insurance plans that are paying this monthly fee, you’re now either providing the service for free to the other 60% of your patient panel or you’re basically running two different clinics (a traditional fee-for-service one and a medical home one) within your single clinic, both of which are designed at odds with each other.

This makes sense you say, but then you remember that hospitals are paid by the DRG (basically a lump sum for the hospitalization, and the amount is determined by how sick the patient was). And since most insurer-hospital contracts are based on DRGs, you say, doesn’t this solve those two problems listed above?

Theoretically, yes. Except that hospitals are the most complex organizations devised by man, and also they do a horrible job accounting for their costs. So, yes, hospitals could innovate in ways that lower costs a bunch and make a killer profit (#pun), but there’s just too much complexity and too many different service lines and too much uncertainty about what things actually cost for them to make much headway in cost-lowering innovations. From a business management perspective, this is a nightmare situation for attempting meaningful change.

But when you have a simpler organization, these barriers go away. And that’s why we see stellar examples of higher quality and lower costs at specialty providers. For example, Shouldice Hospital for hernia repairs (located in Ontario, Canada, of all places!) has made quite a name for itself with its world-class outcomes and low costs.

So, what is needed for providers to innovate? We need to pay for the right products, unify incentives from insurers, simplify hospitals, and get hospitals to learn how to account for their costs.

But wait, there’s more. Even after all that, innovation will still be forever limited until we can ensure that the providers who successfully create value-improving innovations can be rewarded financially, which I’ve written about already here.

This turned into a mini three-part series on healthcare innovation, so I think it’s time for some closing thoughts.

Many people believe that the only solution to our healthcare spending crisis is a government takeover to start administratively lowering prices. This is one of the major arguments for Medicare for All, because “we’ve tried the private market, and clearly it hasn’t gotten it right.” But how much of a solution could Medicare for All be? If the government administratively forces prices down, it hits a hard stop once it has lowered prices so much that profits are 0%. Even if insurers and providers have an 8% profit margin, that means the max possible savings with administrative pricing is 8%. And this does nothing to “bend the cost curve” over time.

The solution, then, needs to be (1) finding ways to prevent more care episodes and (2) lowering the actual cost of delivering care (for the care episodes that couldn’t be prevented).

Over the last 3 weeks, I have shown that, to achieve those two goals, we need to be relying on innovations by insurers and providers. The innovations we need are not happening much right now, but if we can get the incentives right, the barriers to those innovations will go away. (And remember that a single-payer system can be compatible with getting the incentives right.)

How much could these provider-led and insurer-led innovations save us? More than 8%? Based on other industries’ results when incentives are aligned properly, I have reason to believe our healthcare spending curve could flatten, and possible even eventually start angling down. The potential impact of fostering innovation has no comparison to those simplistic administrative pricing approaches that are completely ignorant of how markets work.

%d bloggers like this: