Archive for the 'Science and Medicine' Category

May 19 2020

Low Accuracy in Online Symptom Checkers

A new study published in Australia evaluates the accuracy of 27 online symptom checkers, or diagnostic advisers. The results are pretty disappointing. They found:

The 27 diagnostic SCs listed the correct diagnosis first in 421 of 1170 SC vignette tests (36%; 95% CI, 31–42%), among the top three results in 606 tests (52%; 95% CI, 47–59%), and among the top ten results in 681 tests (58%; 95% CI, 53–65%). SCs using artificial intelligence algorithms listed the correct diagnosis first in 46% of tests (95% CI, 40–57%), compared with 32% (95% CI, 26–38%) for other SCs. The mean rate of first correct results for individual SCs ranged between 12% and 61%. The 19 triage SCs provided correct advice for 338 of 688 vignette tests (49%; 95% CI, 44–54%). Appropriate triage advice was more frequent for emergency care (63%; 95% CI, 52–71%) and urgent care vignette tests (56%; 95% CI, 52–75%) than for non‐urgent care (30%; 95% CI, 11–39%) and self‐care tests (40%; 95% CI, 26–49%).

More distressing than the fact they the first choice was correct only 36% of the time, is that the correct diagnosis was only in the top 10 only 58% of the time. I would honestly not expect the correct diagnosis to be in the #1 slot most of the time. For any list of symptoms there are a number of possibilities. If there are 3-4 likely diagnoses, listing the correct one first about a third of the time is reasonable. You could argue that the problem there is simply not ordering the top choices optimally.

But not getting the correct diagnosis in the top 10 is a completely different problem. This implies that the correct diagnosis was entirely missed 42% of the time.

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May 18 2020

No Benefit from Hydroxychloroquine for COVID-19

In March Trump tweeted: “HYDROXYCHLOROQUINE & AZITHROMYCIN, taken together, have a real chance to be one of the biggest game changers in the history of medicine. The FDA has moved mountains – Thank You!” He has continued to support this untested drug since, turning what should have been a minor footnote in the COVID-19 pandemic into a political controversy.

As evidence of putting politics above science, Dr. Rick Bright claims he was removed from his post simply for questioning the promotion of hydroxychloroquine:

Dr. Rick Bright was abruptly dismissed this week as the director of the Department of Health and Human Services’ Biomedical Advanced Research and Development Authority, or BARDA, and removed as the deputy assistant secretary for preparedness and response. He was given a narrower job at the National Institutes of Health.

In a scorching statement, Dr. Bright assailed the leadership at the health department, saying he was pressured to direct money toward hydroxychloroquine, one of several “potentially dangerous drugs promoted by those with political connections” and repeatedly described by the president as a potential “game changer” in the fight against the virus.

The Plandemic conspiracy theorists promoted hydroxychloroquine as a cure for the pandemic, suggesting the government (yes, the same one headed by Trump) was withholding it to make money off an eventual vaccine.

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May 14 2020

It’s Time for Telehealth

Perhaps one of the positive outcomes of the pandemic is an acceleration of acceptance of telehealth and telementalhealth – treating patients online instead of in person. For example, we have been trying to institute telehealth where I work for years, but have met with roadblocks. Then, all of a sudden, we were able to do it. Our clinic manager estimates that we accomplished in three weeks what would have otherwise taken three years. I have been doing mostly telehealth visits for the last two months now. It’s not perfect, but for many patients it is an ideal option.

The advantages are pretty obvious. A regular visit involves driving into a clinic (which may be in a city, and involves fighting traffic and finding parking), then checking in, and sitting in the waiting room until finally called. Then the meeting happens with the physician. Afterwards you go to check out, and then have to drive home. Depending on the length of the drive, you may spend 2 hours or more total time for 10 minutes of face time with the physician for an uncomplicated follow up visit. Compare this to signing onto an app from the comfort and convenience of your home, having the 10 minute visit over video, then you are done. This also means you are not sitting in a waiting room with potentially sick individuals. Many patients also have a difficult time getting to the clinic. They have physical limitations, and may even require special transportation to get there.

You can even do a limited physical exam over video. Anything that is purely visual and doesn’t require physical contact can be examined. But many patients do not require a physical exam as part of their follow up – their original exam was normal and there is nothing to follow. I see many patients with migraines, for example. Once it has been established that their headaches are indeed migraines (the workup, including exam, for other causes is negative) there is no need for any further physical exam unless something changes. Continue Reading »

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May 12 2020

Do Facemasks Work?

The question of whether or not wearing a facemask “works” is incredibly complicated. It may not seem so at first, but let me list some of the specific questions contained in that broad question. We need to consider different kinds of masks – cloth, surgical, N95. We need to consider who is wearing the mask – someone known to be infected, someone who is well, and in what setting, out in public or in the presence of those known to be sick. We also need to operationally define “work.” We can measure reduction in the spread of the virus, in droplets, in aerosolized particles, and also in different conditions (breathing, coughing) and at different distances. We can measure deposition of virus on surfaces. We can also measure transmission of actual disease, both the chance of spreading and of catching specific illnesses. And of course, all of these questions need to be addressed with each specific infection, and so prior research may not apply perfectly to COVID-19. And further we need to compare the efficacy of wearing a mask to the real-work effectiveness of intending to use a mask.

It should not be surprising, therefore, that we do not have all the answers to these questions specifically for COVID-19. What we have are slices of research with different results and therefore you can look at the preliminary evidence we do have and come to different conclusions. The CDC and the WHO, in fact, have done this. Here is the CDC recommendation:

CDC recommends wearing cloth face coverings in public settings where other social distancing measures are difficult to maintain (e.g., grocery stores and pharmacies), especially in areas of significant community-based transmission.

CDC also advises the use of simple cloth face coverings to slow the spread of the virus and help people who may have the virus and do not know it from transmitting it to others.  Cloth face coverings fashioned from household items or made at home from common materials at low cost can be used as an additional, voluntary public health measure.

Cloth face coverings should not be placed on young children under age 2, anyone who has trouble breathing, or is unconscious, incapacitated or otherwise unable to remove the mask without assistance.

The cloth face coverings recommended are not surgical masks or N-95 respirators.  Those are critical supplies that must continue to be reserved for healthcare workers and other medical first responders, as recommended by current CDC guidance.”

And here is the WHO:

If you are healthy, you only need to wear a mask if you are taking care of a person with COVID-19.

The WHO recommends masks for those who are symptomatic or known to have COVID-19, and those exposed to people who are sick, but not for the healthy out in public. The guidelines are actually not that far off from each other, but there is that one difference.

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May 11 2020

Likely No Summer Break from COVID-19

As is often pointed out, the SARS-CoV2 virus is new, and therefore we have limited data on its characteristics, as well as the disease it causes, COVID-19. This complicates our modeling of what is likely to happen, and recommendations about best practices. But scientists around the world are busy studying this pandemic as it is occurring, and therefore our models and recommendations are evolving.

Already we know quite a bit. For example, one review of NYC patients found:

Among the 393 patients, the median age was 62.2 years, 60.6% were male, and 35.8% had obesity. The most common presenting symptoms were cough (79.4%), fever (77.1%), dyspnea (56.5%), myalgias (23.8%), diarrhea (23.7%), and nausea and vomiting (19.1%). Most of the patients (90.0%) had lymphopenia, 27% had thrombocytopenia, and many had elevated liver-function values and inflammatory markers. Between March 3 and April 10, respiratory failure leading to invasive mechanical ventilation developed in 130 patients (33.1%); to date, only 43 of these patients (33.1%) have been extubated. In total, 40 of the patients (10.2%) have died, and 260 (66.2%) have been discharged from the hospital; outcome data are incomplete for the remaining 93 patients (23.7%).

One question, which is especially important as the northern hemisphere approaches summer, is if SARS-CoV2 is less virulent in warmer temperatures. Coronaviruses in general tend to spread less in warmer months, so there is some reason to hope this will be the case. However, a new review of COVID-19 data pokes a hole in this hope. The authors looked at many countries around the world and correlated the number of new cases with various factors, including temperature and humidity.

To estimate epidemic growth, researchers compared the number of cases on March 27 with cases on March 20, 2020, and determined the influence of latitude, temperature, humidity, school closures, restrictions of mass gatherings and social distancing measured during the exposure period of March 7 to 13.

They found no correlation between the number of cases and temperature, and only a weak association of reduced spread with increased humidity. This is, perhaps, the most comprehensive study to date. There have been numerous previous studies, mostly regional, that do show a negative correlation with virus spread and temperature. The authors suggest this is due partly to lack of rigor in those studies. Also, an expert review of this data (prior to the most recent study) urged caution. They note that the studies showed inconsistent results, and it is difficult to generalize the data to what is likely to happen in the world with COVID-19.

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May 07 2020

Skeptical of Plandemic

A promotional video on YouTube for a new documentary, Plandemic, is making the rounds and promoting quite a response. The video features Dr. Judy Mikovits, and is basically an interview with her. Unfortunately this is a slick piece of utter nonsense and conspiracy mongering. Mikovits has zero credibility in any of her claims, but they are combined with music and clips of videos to create the impression that there is some reality behind her outrageous claims. Let me focus on a few claims to show how low her and the filmmaker’s credibility are.

In her introduction the narrator states that she authors a study in Science that “sent shockwaves through the scientific community” because it showed that fetal and animal tissue in vaccines was causing an epidemic of chronic illness. This is straight up lie, but that is the narrative of this video – that she is a courageous fighter going against the establishment, which is killing people for profit and trying to destroy her for calling them out.

Here is the original Science paper. It alleges to have found the XMRV virus in patients with chronic fatigue syndrome. This did make a splash when it was published because it purported to find a possible cause of an otherwise mysterious illness. It has nothing to do with vaccines at all (although you could argue, falsely that the virus came from vaccines, but that is not what the research was on). But then, here is a retraction of the paper by Science. Was it retracted as part of some global conspiracy against Mikovits? No – it was retracted because:

“Multiple laboratories, including those of the original authors, have failed to reliably detect xenotropic murine leukemia virus-related virus (XMRV) or other murine leukemia virus (MLV)-related viruses in chronic fatigue syndrome (CFS) patients,” says the retraction notice. “In addition, there is evidence of poor quality control in a number of specific experiments in the Report.”

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May 04 2020

COVID-19 Immunity and Vaccines

We appear to be at the beginning of the end of the first wave of COVID-19 (at least in the US – other countries are at different places). We are at the point where states are starting to relax the physical distancing requirements, and there is discussion about how to transition to the next phase. That next phase might include disease tracking, targeted isolation, and “immunity passports.” But planning this next phase is complicated by the fact that we still do not fully understand this virus. We don’t know if there will be a second wave (or more), if it is seasonal, and if you can catch it twice. How we handle this next phase will likely determine if there is a second wave.

But what comes after that? When can we transition to the final phase – return to normal, even if it is a new normal? These next transitions will depend largely on the natural immunity that results from infection, and how long it will take to create a vaccine and how effective that vaccine is. Here is what we know and don’t know so far.

The big question for the next phase is – how much immunity results from natural infection? This is a more complicated question than it may first seem. But the short answer is, we don’t know.

The adaptive part of the immune system will remember infections, B-cells that create specific antibodies targeting the infecting organism will develop throughout an infection, and some of those B-cells are memory B-cells – they will hang around for a long time, ready to produce specific antibodies the next time the same organism is encountered. But there are important variables to how effective this adaptive immune strategy is. the virus or infecting organism itself is the main variable. What parts of itself does it expose to the immune system? Perhaps the critical functional proteins are hidden deep within folds that antibodies cannot get to. Another variable is how quickly does it mutate? If the parts that antibodies can target change quickly, then immunity does not last. Some organisms also evolve specific strategies to evade or compromise the immune system.

Another variable is the severity of the infection itself. The more severe and long lasting the infection, the greater the stimulation to the immune system and the greater the adaptive response.

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May 01 2020

Nanotechnology to Treat Alzheimer’s Disease

This is a very cool study, with the massive caveat that it is extremely preliminary – but scientists have concluded an in vitro study of nanodevices that can reduce one of the pathological changes thought to be a significant cause of Alzheimer’s disease. This has to be put into context, but let me first describe what they did.

Alzheimer’s disease (AD) is a neurodegenerative disorder that affects the brain diffusely. Little by little brain cells die, the brain atrophies, and cognitive ability slowly declines causing dementia. The disease affects about 10% of people over 65, producing a huge burden on individuals, families, and society. As our population ages, it is becoming even more prevalent. There is extensive research on how Alzheimer’s disease progresses, looking for clues that might lead to an effective treatment. However, it has proven a tough nut to crack. We have many clues, but nothing that has lead to a treatment that can prevent, stall, or reverse the neurodegeneration. It is, in short, a complex disease.

One piece of this complex puzzle is the β-amyloid peptide (Aβ), which is a breakdown product of an amyloid protein precursor. The simple version is that this peptide is normally cleared from brain cells as a waste product, but in some individuals it is not sufficiently cleared and there is enough hanging around to form conglomerations or clumps of the protein. These clumps form plaques, which are a major pathological sign of AD. However, the picture is more complex than that. The amount of plaques in the brain don’t necessarily correlate with the severity of the dementia in AD, so it is clearly not the whole picture. More recent studies have found:

Substantial evidence now indicates that the solubility of Aβ, and the quantity of Aβ in different pools, may be more closely related to disease state. The composition of these pools of Aβ reflects different populations of amyloid deposits, and has definite correlates with the clinical status of the patient.

There are also pathological processes in AD that are not related to amyloid plaques, so again we are only dealing with part of the picture here. Still, researchers have been looking for ways to prevent plaque formation as a possible way to slow, stop, or even reverse AD. So far nothing has led to an approved treatment. (Current treatments for AD are only symptomatic.)

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Apr 30 2020

COVID-19 – This is the Harm

Perhaps the most persistent and annoying question promoters of science-based medicine get is, “What’s the harm?” The implication is we should just let people use their Reiki or magic potions if it makes them feel like they are doing something, as long as the treatment is not directly physically harmful. As you can see, I have been addressing it for years, including the fact that I will have to address it for years. There is also well documented real physical harm from many unscientific treatments, but even without that the harm is substantial.

As a physician I have seen first hand much of the harm that can result – such as wasted time and effort, expenditure of limited resources, the psychological harm of false hope, and delaying effective treatment. But I have also warned about the harm to our scientific, medical, and societal infrastructures. This is difficult to quantify, but what is happening is that we are allowing to thrive a multi-billion dollar industry funneling money to charlatans, quacks, con-artists, pseudoscientists, those who discount science, and conspiracy theorists. Do you think they are just taking their money and staying quiet? No. They are using some of those billions to lobby for laws to water down public protections, weaken regulations, and funnel taxpayer money into promoting their snake oil.

This multi-billion dollar industry is also engaged in a massive advertising campaign, which amounts to a disinformation campaign, for their “brand”, which is alternative, complementary, integrative, functional, whatever medicine. They have spent decades misinforming the public about the relative significance of various health risks and benefits, the nature of disease, and the trustworthiness of scientists and experts. They have been a major component in the war on expertise, and to a large extent they are winning.

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Apr 24 2020

UVC and Covid-19

On this week’s SGU (which will go online tomorrow) I talked about the use of ultraviolet light as an anti-viral strategy. I wasn’t planning on also writing about it, but then the president decided to make some incredibly dubious comments about is, so I thought I would address it here. Here’s what he said:

“So, supposing we hit the body with a tremendous – whether it’s ultraviolet or just very powerful light,” the president said, turning to Dr Deborah Birx, the White House coronavirus response co-ordinator, “and I think you said that hasn’t been checked but you’re going to test it.

“And then I said, supposing you brought the light inside of the body, which you can do either through the skin or in some other way. And I think you said you’re going to test that too. Sounds interesting,” the president continued.

He also made some ever sillier comments about injecting people with disinfectant – both comments commit the same error, confusing an external treatment for an internal one., and also suggesting that treatments meant for objects be used on people. So what is the deal with UV light as an antiseptic? The antiseptic effects of UV light have been known for a long time. In 1878, Arthur Downes and Thomas P. Blunt published the first paper describing this effect. Ultraviolet light has enough energy to cause tissue damage – that is why you get a sunburn if you get too much sun exposure.

UV light is electromagnetic radiation between visible light and X-rays on the spectrum, from 10-400 nm wavelength. These are higher energy waves than visible light, with enough energy to cause chemical reactions and damage DNA. UV light is further divided into biological relevant categories of UVA (400-315 nm), UVB (315-280 nm) and UVC (280-100 nm). The ozone layer filters out 97-99% of UV radiation from 315-200 nm, so the UVB and part of the UVC spectrum. Otherwise the suns rays would be much more harmful. On the Earth’s surface there is about 500 times the intensity of UVA than UVB, and almost no UVC. Biologically, UVA penetrates deeper into the skin and does cause long term aging effects. UVB affects the skin surface but causes sunburns and damage that can lead to skin cancer. UVC could cause extreme damage even with minutes of exposure (depending on the intensity).

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