Pediatric traumatic brain injuries

January 10, 2018  |  General  |  No Comments

Traumatic brain injury (TBI) is unfortunately a fairly common thing seen in a typical PICU. Around a half million children are seen in America’s emergency departments each year for head injury. About half of these are mild, but 16-20% are classified as severe. Like most experienced pediatric intensivists, I have seen hundreds of these children over the years, with dozens at least in the severe category. In one sense the term “traumatic brain injury” has limited usefulness because it covers such a wide range of injuries, from mild concussions to more extensive injury, to lethal damage. There can be an associated skull fracture, but often there isn’t. In another sense, however, it’s a useful diagnostic category because the brain responds to a wide variety of injuries in a similar, stereotypic way. In fact several organs are like that, such as the lung.

Our understanding of the manifestations of TBI has grown considerably over the years I’ve practiced. When head CT scans became available we could for the first time assess such things as bleeding inside the skull or swelling of the brain easily and safely, things that allow us to direct our therapy appropriately. I remember how exciting it was when I was a medical student in 1974 doing neurology to see the first simple CT images taken on grainy Poloroid snapshots. Now CT can give us sophisticated, high resolution computer reconstructions of the brain. The technology represented such a breakthrough that its inventors received the Nobel Prize for it.

We soon realized, however, that some injuries to the brain, particularly what we call shear injury, are not well seen on CT — it takes an MRI scan to do that; the CT scan may actually look fairly normal. Another name for this is diffuse axonal injury, which is a good description of what happens. Shear injuries are caused by rapid acceleration/deceleration or rotation of the brain inside the skull from, for example, an impact at highway speeds. They can happen even without a physical blow to the head. These shearing forces essentially break some of the wiring that connects one part of the brain to another. Shear injury can be mild or it can be lethal — it just depends on the circumstances. That aspect is frustrating. Very similar injuries to two different patients can cause significantly different damage between them.

We also came to realize the most important thing we could do in the PICU for a child with severe TBI was to make sure the injury did not get worse: simple supportive measures like relieving pain and keeping the heart and lungs working well were key supportive measures to use while we waited for the child’s brain to heal. We learned to distinguish between what we term primary injury, the initial trauma, and secondary injury, which is what can happen in the succeeding hours to days as the brain responds to the primary injury. Early in my career we didn’t understand that distinction very well. We assumed there was little we could do except wait to see how severe the injury was. Now we understand everything we do during the critical period following the primary injury is crucial for outcome as we support the child during the healing phase. In particular, what first responders do in the field is crucial to what happens afterwards.

Increasing understanding of milder forms of TBI have made us realize it is much more common than we once thought. For children, although the long-term outcome for mild to moderate TBI is good, persistent problems with such things as headache, mood changes, and difficulties in school are not uncommon, and these can last for months. We also are coming to understand the bad effects of repeated injury, even if each individual event is mild. The effect can be cumulative. The disorder known as chronic traumatic encephalopathy was recognized, especially among professional football players who experience years of repeated blows to the head.

There is a great deal of information available about TBI. There are many misconceptions about it, too. As usual, Google can be a mixed blessing. You can find authoritative, respected advice from the Brain Trauma Foundation. This is an outstanding organization and you can also learn there some of the specifics of how we manage traumatic brain injury and why. This is also a useful site for more information.

It shouldn’t need to be said, but put a helmet on you child when they are skateboarding, skiing, or riding a bike. That’s enormously important to preventing or minimizing TBI.

New evidence childhood obesity is an enormous threat to our nation’s health

December 27, 2017  |  General  |  No Comments

We’ve known for some time the prevalence of obesity is growing among Americans — not just adults, but children, too. Obesity is associated with a long list of medical problems, including heart and other vascular diseases, diabetes, and joint problems. It is encouraging that recently the seemingly inexorable growth of pediatric obesity prevalence seems to have reached a plateau. But we still have a future problem looming for population health as these children grow up. A recent article in the New England Journal of Medicine evaluates a couple of key questions regarding obesity in children. The article, entitled “Simulation of Growth Trajectories of Childhood Obesity into Adulthood,” evaluates predictions of what will happen to our population health over the coming decades.

The authors used methods that are a bit complicated statistically and I’m certainly not competent to evaluate the details of them. But as I understand it they used existing data sets on childhood obesity to predict the prevalence of obesity at 35 years of age, the point at which the health risks of obesity begin to manifest themselves. Previous obesity studies had used fixed cohorts of individuals followed over time. The problem with that is that the dynamics of the population are changing, and presumably environmental risk factors as well. The model in this study allowed for new individuals to be constantly joining the cohort to control for these effects.

At any rate, the findings of this simulation were striking to me. Panel A below from the paper uses several models to indicate that by mid-century just over half of the population will be obese. Panel B follows a hypothetical cohort of 2-year-olds that essentially predicts the same thing. The authors defined obesity in the usual way: a body mass index (BMI) of greater than 30, with BMI defined as weight in kilograms divided by the square of height in meters.

The authors’ overall conclusions are kind of a glass half-empty/half-full kind of thing for pediatricians. Their simulations indicate that around half of adult obesity is attributable to childhood obesity, and the rate of childhood obesity has been improving recently. That’s good and gives me hope for the future. Children who are not obese have a lower risk at being so at age 35, whereas those who are already obese in childhood have an extremely high risk of being obese at age 35. So as pediatricians we can have a huge effect on the problem of obesity in the adult population. In the authors’ words:

Although a broad range of public health and clinical efforts appear to have stabilized early childhood obesity rates, in this study we estimated that among children between the ages of 2 and 19 years in 2016, more than half (57.3%) will be obese by the age of 35 years. . . . about half of the total prevalence of obesity began in childhood, and adult-onset obesity by 35 years of age accounted for the rest.

It’s a sobering thought that over half of adults will be obese. There are various theories to explain this, but I think the common sense one is best: we eat more calories and our lives are progressively more sedentary. The processed foods many of us eat are extremely dense in calories compared to meals we used to eat. Some evidence has implicated the increasing use of high-fructose corn syrup in such foods. These changes in diet and lifestyle have occurred very rapidly and we have not adapted. Pediatricians can help in the needed adaptation because all obese adults started out as children.

Insidious harm to PICU parents from prosperity gospel thinking

December 11, 2017  |  General  |  No Comments

I majored in history of religion in college and have always had an interest in the places various twists and turns of theology can lead people. One relatively recent wrinkle is what has been loosely termed prosperity gospel or prosperity theology. It’s built upon the basic notion good things happen to good people and bad things happen to bad people. Of course that’s a foundational viewpoint of much of Christianity in the sense that virtue is rewarded and sinful behavior is punished in the great beyond. Protestant groups with strong traditions of predestination theology don’t see things exactly that way, but over the past century I think it’s fair to say most American denominations believe virtue is eventually rewarded (or is its own reward). The key word here is eventually.

Prosperity gospel, the origins of which most historians place in the 1950s or so but which really blossomed with the advent of televangelists, puts a new wrinkle on the centuries-old formulation of rewarding virtue. The basic idea is that faith and good works are not only rewarded in the next life, but also in this one. And that reward is very concrete. If your faith is strong you will be rewarded with success, especially riches in this world, as evidence of God’s favor. The darker, flip side to this viewpoint is that poverty is largely a person’s fault and perhaps even a sign of God’s disfavor. An extension of this way of thinking is the implicit, or sometimes explicit idea that personal good health and a happy, healthy family are also signs of godliness; in contrast, ill health or sickness in one’s family represent the reverse. It’s the second of these I’ve seen poison situations in the PICU.

Families with critically ill or injured children in the PICU are under enormous stress. I have always regarded religious faith as generally a good thing for families to have because it often helps hold them together in such stressful times. But over the years I have also seen the toxic effects of parents thinking their child is ill because their faith has not been strong enough. Parents often come to the PICU with this kind of thinking already bothering them in nonreligious ways: “I shouldn’t have driven down that road,” or “I shouldn’t have let my child go swimming.” If one adds to that: “My faith was not strong enough,” you can easily see where this can lead. The absolute worst cases I’ve seen are when families belong to a church group whose members imply a child’s misfortune is proof of the substandard zeal of the parents. It’s devastating.

Now and then I’ve spoken about this to pastors and ministers who participate to some degree in prosperity gospel thinking. Not surprisingly, all deny such a thing is a problem. But the more thoughtful ones understand how it can happen. To me it’s an example of how the practical working out on the ground of abstract theology affects daily reality. I’ve always felt my background and training in religion has helped me greatly in practicing pediatric critical care. I work in one of the most technical fields of medicine, yet paradoxically what I do is in some ways the furthest removed from technology.

Dealing with requests for futile end of life care in the PICU

November 27, 2017  |  General  |  No Comments

Most experienced pediatric intensivists, myself included, have encountered situations in which we, the doctors, believe continuing to support a child is unethical because it is not saving the life but prolonging the dying; whereas the child’s parents believe the opposite—that it is unethical to withdraw life support because all life is sacred, no matter the circumstances. Sometimes these situations arise because poor communication causes families to distrust the doctors. But sometimes both sides understand each other clearly, but still disagree profoundly about the proper thing to do. What happens then?

Doctors often make the argument that we should not prolong suffering, and most people agree with that in my experience. Establishing if a patient is actually in pain can be difficult, and anyway we virtually always have the means to relieve pain in these situations. More telling to me is the argument that families cannot compel physicians to act unethically, and futile care is unethical. (You can read an excellent piece about the history of this concept here.) Yet even then, in theory, the physician can simply withdraw from the case, although from experience I can tell you it is difficult to find another physician to take on cases like this, and abandoning our patient without finding them another physician is clearly unethical (and illegal). All hospitals, particularly large ones with PICUs, have ethics committees in place to help in these situations. The goal is to bring in people experienced with examining  such questions and who have no connection with the particular case. The committee examines all points of view — family, physicians, PICU staff — and gives a recommendation. That recommendation, however, is in most places only advisory, not compulsory. What happens if the family and the child’s physicians still disagree about what to do?

Dr. Robert Truog, a medical ethicist at Harvard, discussed such a case from a decade ago here. It is an excellent introduction to the topic. One wrinkle, however, is that in Texas the 1999 Advanced Directives Act allows a hospital to act against a family’s wishes and withdraw futile care if the hospital ethics committee rules against them. I don’t know of any other state that allows this. The hospital must give ten days notice and attempt to transfer the patient to another provider. The law has not been without controversy. Dr. Truog provides a careful analysis of this particular case, which was a child named Emilio Gonzales with Leigh’s disease, a progressive neurological disorder that typically leads to death by two years of age. He makes a valid argument that the child in question was not suffering unduly. He also argues that continuing to provide life support as the child’s mother wanted, although costly, should not be a consideration because the number of such cases across America is small and thus the contribution of their care to the total national healthcare costs is trivial. He also points out that hospital ethics committees are inevitably weighted toward physicians and other healthcare professionals who are far more likely than not to agree with the treating physicians in the PICU. In the end he decides the Texas statute is not a good thing and should not be generalized nationally.

Rather than jeopardize the respect we hold for diversity and minority viewpoints, I believe that in cases like that of Emilio Gonzales, we should seek to enhance our capacity to tolerate the choices of others, even when we believe they are wrong.

I have been involved in several cases like the one Dr. Truog describes. Thankfully, in all but one the family and the doctors were ultimately able to reach an understanding both sides accepted. In the one case in which we could not agree, nature ultimately decided things for us, as she often does. That is what also happened with Emilio Gonzales, who died before the conflicts were resolved. For myself, I agree with Dr. Truog. We should do our best to explain and understand, not once but continually, and ultimately agreements will be reached in virtually all cases.

Cases such as this are extremely rare, but they remind me that the pediatric intensive care unit is a place where, if we pay attention, we can learn a great deal both about life and about ourselves.

Effect of the weightlessness of space on the brains of astronauts

November 19, 2017  |  General  |  No Comments

This one isn’t about critical care or childhood illness but nonetheless I found it fascinating. Humans evolved with the constant force of the earth’s gravity. This is relevant to several of our organs, but the brain’s anatomy makes it especially important. The brain floats in spinal fluid encased inside the closed box of the skull. Gravity would be expected to affect the details of that. Indeed, studies of people who spent prolonged periods of time in bed in a head down position indicate this abnormal situation causes changes in the brain. The authors of this study examined what prolonged exposure to near zero gravity in space did to the brain. They used MRI imaging to study two cohorts of astronauts: those who experienced short space flights and those who spend many months in the space station. MRI is very good for things such as estimating brain volume and in particular studying the fluid in and around the brain. As a background, it has been known previously astronauts may experience some swelling of their optic nerves, with resultant visual disturbances, as well as elevated pressure inside the skull. The question was if these changes related to duration of time spent in space.

The data showed some significant differences. Astronauts in prolonged flights were more likely to have optic nerve swelling. Long flight subjects also had significant increases in the fluid volume inside their brains, as measure by ventricular size. The mechanism for that may be some obstruction of fluid flow from the center of the brain to the outer surface. There were several other differences noted in the article as well. Below is an MRI image showing one such difference, crowding of one of the brain sulci. The sulci are the fissures between the folds of the brain surface that allow the total surface area of the cortical part of the brain to be much larger than it would be otherwise. The importance of this is well shown by the problems experienced by children with the congenital condition lissencephaly, in which the brain is more smooth so cortical volume is much less. These are T2-weighted MRI images, in which fluid is shown as bright white. The images show the fluid down in the sulci, between the folds in the brain surface.

Images A and B show one astronaut before (A) and after (B) prolonged flight. Images C and D show a short flight astronaut before and after exposure to space. The white signal is fluid. If you look at the sulcus indicated by the asterisk in A and B you can easily see how the area is kind of squished down after prolonged flight. That particular astronaut also had visual disturbance symptoms. There is no difference in the before and after images of the short flight astronaut.

Besides being interesting I think this is important because it reminds us our bodies have evolved under a specific set of conditions, such as 21% oxygen concentration and the earth’s gravity. We have long known gravity is important to bone physiology because our bones rely on weight bearing to stay healthy. Now it appears the brain, too, often undergoes changes when exposed to zero gravity, changes which are physiologically important. Any planning for future space travel, say to Mars, needs to consider this and how to counteract detrimental changes. It is still unknown if these brain changes in the long flight astronauts persist for a long time once they return to earth; that is currently under study.

Update on respiratory syncytial virus (RSV): Are we making any progress?

October 13, 2017  |  General  |  No Comments

It’s fall in the PICU and we just saw our first severe case of respiratory syncytial virus (RSV) of the season. RSV is by far the most common cause of bronchiolitis in infants. To scientists, RSV is a fascinating virus with several unique properties. One of these is its behavior in the population. When it’s present, RSV is everywhere. Then it suddenly vanishes. There are exceptions to everything in medicine — I have seen sporadic cases during the off-months — but generally RSV arrives with a bang in mid-winter and then leaves suddenly in the spring. It’s the only virus that consistently and reliably causes an epidemic every year, although it often alternates more severe with milder visitations. RSV epidemics often have some regional variability. For example, often one city will have a much more severe epidemic than do others in other regions of the country. RSV has a high attack rate — the term scientists use for the chances a susceptible person will get the infection if exposed to it. That, plus our generally poor defenses against it, explain the frequent epidemics. Every year a new crop of susceptible infants enters the population. By the age of two virtually all children have had RSV infection.

One aspect of RSV that interests medical scientists is how poor a job our immune systems do in fighting it off. Virtually all children are infected with RSV during the first few years of life. Not only that, all of us are reinfected multiple times during our lives. Attempts at devising a vaccine for RSV have thus far been unsuccessful. In fact, early versions of an experimental vaccine seemed to make the disease worse in some infants, raising the possibility some aspect of our immune response to the virus actually contributes to the symptoms. RSV is generally not a serious illness, causing cough and some wheezing, but for some children it can be life-threatening. Usually these children are very small infants, especially those born prematurely, and those with underlying problems with their lungs or hearts. For those infants we have a monthly shot (called Synagis) that helps reduce the severity of RSV when they get it, and may even prevent a few cases, but it is not an ideal treatment. Older and otherwise normal children, such as toddlers, can also get severe cases. We have no idea why that is, although it appears to me children with established asthma often get more severe disease.

So what is bronchiolitis? What does it look like? In medical terminology, adding the ending “itis” to a word means whatever comes before is inflamed. Thus tonsillitis is an inflammation of the tonsils and appendicitis means an inflamed appendix. So bronchiolitis is an inflammation of the bronchioles, the final part of the system of air-conducting tubes that connect the lungs with the outside world. Beyond the bronchioles are the aveoli, the grape-like clusters of air sacs where the business of the lungs — getting oxygen into our bodies and carbon dioxide out — takes place. Bronchiolitis is a disorder of blocked small airways. This prevents air from getting in and out normally, primarily out. The bronchiole tubes are blocked from swelling of the walls and from debris caused by the RSV infection — bits of broken airway cells and mucous plugs. This picture shows what it looks like.

For my entire 35 year career we have had no specific treatments for RSV bronchiolitis. Various things have been tried over the years but nothing seems to help. Care is supportive, meaning we use oxygen, frequent suctioning of mucous, IV fluids or nasogastric tube feedings if the infant cannot drink, and a mechanical ventilator for severe cases. We just have to support the child until the infection passes. But researchers have not given up on an RSV vaccine. There are several candidate vaccines in the research pipeline and the World Health Organization predicted in 2015 we will have one within a decade.

If we don’t have a vaccine to prevent RSV, what about a drug to treat it, to inactivate the virus? Several agents, such as ribavirin, have been tried in the past and rejected. We may be making progress on that front, however. A new drug (GS-5806) has been identified that inactivates RSV in the laboratory. It has also been tested in normal adults. They were given the test drug and then challenged with the RSV virus. The drug did not prevent disease but it did significantly reduce the symptoms and the total viral burden. There are now several clinical trials underway testing the drug in adults who are at high risk for severe RSV, those with compromised immune system. It seems to help. That’s all fine, but what we really need is information if it works in infants and small children, and as of yet there are no clinical trials to answer that question. One from Australia was apparently started but then withdrawn, reasons not stated.

So, to answer my question in the title: Where are we with RSV prevention and treatment? I agree with WHO that we will eventually get a vaccine, a drug, or both. But right now we’re still stuck where we were when I started doing this in 1978 — supportive care. It’s frustrating but RSV is a wily virus. Right now the best thing parents can do is try to postpone their infant getting it for the first time, especially if your child was born prematurely.

 

About those online physician rating services: a personal study of one physician

September 5, 2017  |  General  |  No Comments

A surgeon whose popular blog is named Skeptical Scalpel put up an interesting post recently about those online physician rating services. In theory, of course, it’s a great idea for people to give their opinions and rate their experiences with any goods or services they buy. The notion goes back long before the internet with publications like Consumer Reports, which is now itself online. Sites such as Angie’s List are very popular and can give you testimonials about providers of everything from home renovations to car repair to daycare. So it’s not surprising several entrepreneurs have started physician rating sites. The Skeptical Scalpel wondered about how useful these are to patients and families. He thinks not much. A huge issue is the sample size is so tiny; many physicians get only a single review. Also, the reviews are anonymous and there have been several well known examples of stalkers trashing a physician’s reputation out of some animus to the person. It’s also well known perhaps a fifth or so of reviews at sites like this are fake anyway.

So I wondered. I’ve been practicing for 35 years and cared for thousands of patients. I have moved a few times and now work at several hospitals, so perhaps I’m hard to track down correctly, but maybe not. Also, rating pediatric critical care providers for patient choice reasons seems silly on the face of it because nobody shops around and plans for things when their child is suddenly critically ill or injured. You just go to the nearest place and are treated by whoever is there. Still, I thought it would be interesting to look. I would imagine I was a parent looking to get the inside scoop on that Johnson guy. The sites generally contain some biographical information about the physician — address, insurance accepted, where he or she trained, if he or she had ever been disciplined by an official body. I wondered how accurate that would be for me. So here we go.

US News and World Report: This site listed me. It had my correct address and correctly listed my specialty, medical school, and years of practice (although it only said 21 plus). It was correct in all my training data and even listed a couple of awards I’ve gotten. It looks as if they obtained my CV from Doximity, a physician site. They did miss several of the hospitals where I have credentials, including the one where I mainly practice, but they did get my various medical licenses correct. On the other hand, they didn’t rate me at all. So if I were a parent checking up on me I’d only have my credentials to go on.

Health grades: This one got my main hospital correct, unlike US News. It also got my years of practice correct. But there were no reviews of me at all.

Vitals: I’m listed on this site. The details of my training are skimpy but what is there is correct. They also got my main hospital affiliation correct. I got 1 review — 5 stars (WooHoo?). I’ve seen hundreds of patients at that hospital, yielding 1 review.

MD.com: This one was hopelessly wrong. It stated I practice primary care pediatrics, which I don’t and never have, and it had an address for me that was 10 years out of date. It had no reviews of me. I suspect this website was just abandoned by its owners.

UCompare: These guys had me listed. The address was wrong and there were no reviews.

RateMDs: I wasn’t listed.

ZocDocs: I wasn’t listed.

WebMD: This is a huge site. Most people use it for information about diseases but it also lists doctors. It listed me, but there were no reviews.

So there you have it. I’ve cared for thousands of children over the years and many hundreds since these doctor rating sites have been around. I had 1 review. It was a great one, but really, I can’t see that any parent would have found searching for information about me to be useful. The great majority of Google hits were to this website, the one you are reading now.

Little known fact: Believers in fake science are now running Department of Health and Human Services

August 29, 2017  |  General  |  No Comments

There was a recent sobering editorial in the New England Journal of Medicine that caught my eye. Its title was “Alternative science and human reproduction” and its author is R. Alta Charo, professor of law and bioethics at the University of Wisconsin. It’s been clear now for decades that significant numbers of prominent Republicans either believe or profess to believe things about human reproduction that simply aren’t true. Examples include the debunked notion abortion is associated with increased breast cancer risk or hormonal birth control works by causing repeated abortions, that birth control pills are “abortifacients.” In the words of the editorialist:

Human reproduction has become the victim of alternative science, rife with alternative definitions of well-understood medical conditions and characterized by rejection of the scientific method as the standard for generating and evaluating evidence.

Several recent appointments to the Department of Health and Human Services are disturbing in this regard. The new deputy assistant secretary of HHS for population affairs has openly stated the government has no role in the very thing her job is. She also asserts the absurd idea hormonal contraception is ineffective in spite of overwhelming scientific evidence to the contrary. Another Trump appointee, Charmaine Yoest, has this in her curriculum vitae:

Yoest, former head of the antiabortion advocacy group Americans United for Life, helped to develop the strategy for a Texas statute that was so filled with obstacles to abortion services, presented in the guise of protections for women’s health, that the U.S. Supreme Court abandoned its usual degree of deference to state legislatures and struck down the law because its underlying factual claims were patently false.

But there’s more. Katy Talento, another new appointee, claims contraception causes infertility and miscarriages, claiming contraceptives are “breaking your uterus.” These are the people now in charge. They don’t understand science. Worse, they don’t want to understand science if it conflicts with their existing beliefs. They have the power to do immense harm to the public health, particularly the health of women.

 

The vaccine deniers’ unicorn: their demand for comparison study of vaccinated and unvaccinated children

August 19, 2017  |  General  |  No Comments

I swiped this editorial cartoon by Steve Sack from the redoubtable Dr. David Gorski’s blog, who goes by the nom-de-web of Orac. Recent epidemiology shows reducing the fraction of vaccinated children in the population rather promptly leads to a resurgence of the diseases vaccines protect against. This is the concept of community or herd immunity. Epidemiologists debate the concept around the margins but overall its importance is well accepted. People who deny the effectiveness of vaccines or even think vaccines are dangerous don’t accept it, though, and you can find many examples of this around the internet, some sort of reasoned, some not. Although I’m trained in pediatric infectious diseases, a field that includes a lot of epidemiology, I’m not an epidemiologist. So I’m not going to chew on the whole herd immunity thing. I’m going to write about a particular form of concern trolling common among vaccine denialists: the claim that they would fully support vaccines if only vaccines could be shown to be fully safe and effective, using their own special definitions of what that means. In effect they erect an impossible standard to meet, which is of course how concern trolling works.

A common claim is that, although individual vaccines may be safe, the safety of combinations of vaccines together has never been shown. It’s not always clear what the demand is here, but it often appears to me to mean they want a trial of all the many possible combinations of vaccines compared. If you just do the math on how many vaccine combinations are possible you can see this demand is absurdly impossible to meet. We actually do have ongoing surveillance of vaccine safety happening all the time and the results show them to be the safest medical procedure we have, with around 1 complication per million doses administered. The only thing safer is homeopathy, which does nothing but harms nothing. Vaccine denialists elide this fact by redefining what a vaccine complication is through including nearly anything that happens to a person afterwards, even years afterwards, as vaccine-caused. I’ve read posts by many adults who claim, for example, that their fatigue, difficulty concentrating, and “metabolic problems” stem from vaccines they received as children.

And then there is the mythical unicorn vaccine denialists claim is the only acceptable answer: a direct comparison of vaccinated and unvaccinated children, searching for differences in outcomes. Key here is the frequent claim unvaccinated children, on average, are healthier than vaccinated ones. To someone who knows little of clinical research this seems like a perfectly reasonable demand. Just compare vaccinated to unvaccinated children, see who got illnesses or complications and who didn’t. I just saw this one on my Twitter feed today:

Also note this tweet includes the common fallacy the Amish don’t vaccinate — most do. Anyway, there have been some terrible studies of this sort reported, such as this one, which highlight the fallacy of doing such a simple comparison without controlling for any confounders. Fundamental to any proper study like this is that the two groups being compared, in this case vaccinated and unvaccinated, must differ only in the variable being tested. A common way of handling the question is a case-control study, in which each case is matched with one or more controls that, as best as can be determined, satisfy that requirement. But vaccinated and unvaccinated children, by parent choice, are hopelessly self-selected right out of the gate. There are other confounding issues, such as blinding, but that’s the main one.

Well then, as some have actually demanded, we must have a randomized controlled trial (RCT), the gold standard of clinical research. RCTs use random assignment of subjects to one group or the other, in this case vaccine or a placebo (fake vaccine), and ensure both the subjects and evaluation team be blinded to who got what. Think about this for a minute. They are demanding parents agree to subject their child to a trial in which they have a 50/50 chance of getting a fake vaccine. All this to satisfy the concerns of vaccine deniers. It would be incredibly unethical to do such a study, and no institutional review board (aka human studies committee) would ever approve such a thing. For such trials there must be reasonable uncertainty about which group is getting the better treatment and in this case there is none. The bottom line is any vaccine skeptic who demands proof like this is being massively disingenuous. It’s akin to demanding a randomized controlled trial of parachutes.

The enduring mystery in this perennial chestnut of a topic is that vaccine deniers demand a level of safety and certainty from vaccines that they demand from no other medical procedure or treatment. Absolutely every treatment I can think of is riskier than vaccination. Some are far, far riskier. I suppose it’s partly owing to a visceral resistance to injecting something into a healthy person, but vaccine denial in general has deep, deep historical roots.

Even low levels of air pollution are associated with increased mortality

July 19, 2017  |  General  |  No Comments

This post isn’t specifically about children; it’s about the elderly, Medicare population. Even so I found this article newsworthy. It’s long been known air pollution is associated with increased asthma rates. I’ve written about asthma in children. Decreasing air pollution leads to reduction in asthma, an encouraging trend. There have also been long-term studies showing a correlation between air pollution and overall mortality among all ages. The offending agents in the polluted air are ozone and fine particles, those with a diameter of less than 2.5 microns, a size too small to see with the naked eye. So it’s established chronic exposure to polluted air is bad. But what about exposure to any air pollution at all, to air we wouldn’t ordinarily think of as polluted? In other words, is there a safe threshold?

Air pollution of course varies from place to place across the country. Here is an instructive map about that. The top panel shows the fine particles, the bottom one ozone.

 

The investigators used an enormous database consisting of the entire Medicare population of 61 million persons studied over 12 years (2000-12). It totaled 460 million person years. Ten person years, for example, is 1 person followed for 10 years or 10 persons for 1 year. That’s huge. The authors’ goal was to find out if lesser degrees of exposure to air pollution, values half or less of those usually regarded as dangerous, were associated with increased mortality. They found they were, at least in the elderly. The graphs below display what they reported. Again, the top panel shows particulates, the bottom panel ozone. The left axis shows the hazard ratio for death, with a value of 1.0 meaning no hazard.

 

What the data show is what is called a dose-response curve. This is an important part of any study of potential cause and effect because, if the association of something potentially causing something else is real, you should see an increased effect if the dose is increased. Sometimes such curves plateau if maximal effect is reached, but these graphs show steadily increasing risk of death with increasing air pollution.

I think this is significant research. It suggests there is no safe level of polluted air. The editorial accompanying the paper agrees: its title is “Air Pollution Still Kills.”