Clinical research — finding out which treatments help and which ones don’t (or even make the situation worse) — is tough research to do. In the laboratory a scientist can control conditions so that only one thing changes, isolating the effect of a particular thing. Clinical research is different because humans are complicated. The researcher tries to control the situation as much as possible, but ultimately she is comparing one dissimilar human to another one.

The result is that a lot of clinical studies, interventions in which researchers give patients this or that medicine and then try to find out if it worked, are underpowered. This means the studies aren’t powerful enough to answer the simple question: does this treatment help?

Recognizing this problem, the concept of “meta-analysis” was devised. The idea is that one can take a bunch of underpowered studies and lump the information together. This can create, in effect, a single study with enough power to answer the question. Critics compared meta-analysis to making a silk purse from a sow’s ear — trying to take a lot of poor studies and make a good study from them. This can be a problem. But if you’ve ever taken your child to the doctor for treatment of croup, you and your child have been the beneficiaries of what meta-analysis can accomplish.

Croup is caused by swelling of the airway from a virus (see the link above for details), and corticosteroid medicines reduce swelling. So it seemed logical to try them for croup. But although some of the early studies suggested steroids helped, they were all underpowered to answer the question for sure. Then somebody did a meta-analysis with the data and showed steroids probably helped. This information then led other researchers to spend the large amount of time and effort to do some fully-powered studies. The results? Steroids, by mouth, injection, or even inhaled, help relieve the symptoms of croup.

So in this case it was a silk purse all along.

I’ve recently been looking over the statistics about this blog. The most popular posts are those which talk about common issues — croup and concussions, for example. But one of the most often read posts gets its popularity from people using search engines like Google to answer this question: how risky are x-rays, especially CT scans, to children? You can read my actual posts about that here and here, but what struck me most about the popularity of this topic is what it tells us regarding how we think about risk. In particular, how do we tend to think about the risk of events occurring which are very rare, but which carry grave consequences if they happen? Lawyers call these events “small probability — large loss events.” Economists have studied the subject quite a bit, too, especially as it relates to investment decisions people make.

We humans are not entirely rational when we think about risk. We tend to focus on low-probability but high seriousness events, particularly if we are thinking about them in the context of choosing to do or not do something. So, for example, if your child needs a CT scan, as a parent you many think about how the radiation in that test increases your child’s chances of getting cancer. What we don’t think about is that your child is far, far more likely to suffer harm in a car accident while you are driving to the CT scanner than he is to suffer harm from the scan. But since we drive our children around every day, we don’t think much about that risk.

According to the National Cancer Institute, a child’s overall risk of developing any form of cancer is 1-2/10,000 children, or 0.01-0.02%. Also according to the NCI, this number has changed very little, if at all, over the past 30 years. The use of diagnostic x-rays in children, especially CT scans, has increased enormously during that time, so we should be reassured by these statistics. Even so, radiologists are increasingly vigilant about how they can reduce radiation exposure when they use x-rays.

Bottom line — it is always worth asking if the risk of a test exceeds the value of the information the test will give. But for x-rays, the benefit virtually always outweighs the risk.

I’ve written before (here and here) how well-documented it is that poorer children tend to have more serious illnesses. For example, although children on Medicaid (a good marker for family income) account for around a quarter of all children, about half of the children in most large PICUs are on Medicaid. Thus poorer children are twice as likely to suffer serious illness or injury.

I’ve never seen any scientific explanations before about why this is so. Certainly it makes sense that the better fed, clothed, and housed a child is, the more healthy overall that child will be. Affluent children also are more likely to have good heath insurance with good access to preventative care, so a chronic condition like asthma or diabetes is more likely to be kept under control.

These explanations, though probably part of the answer, always seemed sort of vague to me — soft data. The scientist in me wanted some biological explanation, some harder data that might explain what is happening. I recently ran across some research that takes a few steps down that path.

Two professors at Cornell recently reported in the journal Psychological Science their findings in poor children on some well-known biological markers of stress. (You can find a summary of their article here.) In their study of thirteen-year-old children, they found much higher biological markers of stress — blood pressure, levels of stress hormones in the body, and the ability of the body to respond to stress. All of these things are known to affect illness.

They also found that poverty early in life tended to establish in children these abnormal responses in a way that they didn’t improve later, even if the child’s economic circumstances improved. So early poverty has life-long effects. You can find a more general discussion of the research and its implications here.

Findings like these reinforce the argument that one of the best ways to improve Americans’ health is to reduce levels of poverty, especially among children.

Every PICU cares for teenagers who are injured in car accidents. Many times these adolescents have been drinking alcohol. We also see teens in whom alcohol has led to a variety of other injuries besides car accidents. So underage alcohol use is a PICU issue. What do we know about it?

You can find some statistical answers to the question here, courtesy of the United States Department of Health and Human Services. Overall, alcohol is the most commonly abused drug by teenagers, dwarfing all others, including tobacco. In fact, underage drinkers consume eleven percent of all the alcohol consumed in the United States, an astonishing statistic. Nearly half of high school children report drinking some amount of alcohol during the previous month, and half of those teenagers did so during a session of binge drinking, defined as five or more drinks on a single occasion. By the time they graduate, three-quarters of high school students have tried alcohol. Among even younger children, forty percent of eighth-graders have tried alcohol, and sixteen percent of them report drinking within the previous month.

Those are the cold, abstract statistics. But teen drinking is not just about statistics–it is about individual children and what happens to them. Overall, a child who starts drinking as a young teen is four times more likely to develop alcohol-related problems as an adult than is a person who does not use alcohol until becoming an adult. Such children are also more likely to abuse other drugs, develop school problems, or engage in early and risky sexual activity. All these things correlate with teen drinking; they are not necessarily caused by it. Even so, such ominous associations tell us we should be greatly concerned.

One of the most dangerous problems connected with teen drinking is drunk driving. It is common among teens–ten percent report having done so. An even larger number–one third of all teenagers–report having ridden in a car during the previous month driven by a teen who had been drinking. Motor vehicle accidents are the leading cause of death among teens, and many of those who die show evidence of recent drinking. Although alcohol impairs the reaction time and abilities of all drivers, inexperienced teen drivers are even more affected. All these dry statistics translate into the unique, individual tragedies of thousands of teens killed or injured.

What can a parent do about teen drinking? Does any intervention help? Talking to your children about alcohol before they find out about it on their own is not only commonsense advice, it actually works. For example, one survey showed that parental disapproval was a far more powerful deterrent than were legal restrictions to getting alcohol. Teenagers whose parents talk to them frankly about alcohol, including a firm expectation that underage drinking is not acceptable, are less likely to drink. Equally important, parents who themselves use alcohol need to set an example of responsible behavior, especially with regard to driving.

You can find more excellent discussions, answers, and comprehensive resources for parents here, part of the recent Surgeon General’s initiative to reduce underage drinking.