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Relative Risks and Why Anecdotes Can be Lousy for Making Decisions

August 21, 2010

Fear blinds us, immobilizes us, and makes fools of us. Scary stories abound on the internet, through emails, and in conversations, and dangers lurk in the dusty corners waiting to pounce on us and tear our loved ones from our grasps. We know this. We feel it viscerally. And sometimes we shake in our boots. 


We’ve got enough real dangers, and we do, without adding in made-up ones. We do a terrible job at assessing risk. Don’t believe me? Which is safer? Driving or flying? If you said driving, you’re so terribly wrong and have let both the illusion of control and the availability heuristic make you run with your gut. 


If we admit this truth, that we are bad at assigning risks, then we should be looking for what science, statistics, and probability have to show on relative risks before we go off with our guts thinking we’ve chosen the least risky decision.


And I write this as a mom who lives this, every day. Your gut is not what you want to go with when you’re making medical decisions. It isn’t. You want some good hard data to back your decisions. My son has factor V leiden, a blood clotting disorder which caused a stroke when he was nine. At that time, once the doctors determined he had the disorder, we had to decide on preventative treatment. Do you give a nine year old coumadin for the rest of his life? Our doctor decided with one stroke to go on that the risks of coumadin were greater than the risks of another blood clot. Our son went on the less risky aspirin. If you have kids, you know that aspirin in children can be dangerous. It was a game we played, pulling aspirin when he had colds. Falls, bumps, bruises are scary. Will it lead to overclotting?  Bumps to the head? Beyond terrifying still to this day.


When he had his wisdom teeth out, he was sent to a hematologist for an alternative to aspirin in the weeks leading up to the surgery. The doctor was horrified that he’d been on aspirin for a decade instead of the standard coumadin and immediately wrote a prescription for that for after the surgery and one for lovenox injections leading up to the surgery. 


And I started digging through the literature, pulling up articles showing that where there had only been one incident (especially with a decade with no additional ones), that lifetime coumadin, indeed coumadin for one year, conveyed far greater risk (3 out of 100 patients have bleeding problems on coumadin in a year, with 1 death for every 200 patients on coumadin from excess bleeding). My son’s real risk of a thrombolytic event was around 5 in 1000.  You can see right there that the risks were vastly higher on coumadin than off, and after consulting with an academic hematologist, my son’s doctor deferred to his judgment and back on aspirin my son went.


When your family member’s life is at stake, fear can be deadly, especially if it paralyzes you. It’s incredibly hard to make sound, rational decisions when fear has coiled itself in your gut and twisted you in knots, so in order to be collected in crisis, you have to practice those reasoning skills in calm times. You have to look at the evidence dispassionately, and you have to defer to experts who know better. Sometimes that is indeed your immediate doctor, but even they can be paralyzed by fear and can make rash decisions. 


When you’ve got a chronic condition, you’ve got to become the expert on it because chances are your doctor or your child’s doctor won’t be, won’t have the latest literature, and won’t have thought out hypothetical situations before hand and will simply react, as my son’s hematologist did.


It’s okay, when it’s not an immediate life or death situation to step back and say wait a minute, is that really standard of care? Is that what the guidelines call for? If you’re deviating, what is your reasoning for it? It’s hard to do, but it’s your child’s care.


The trick, though, is to find reputable sources, and just because it’s on pubmed doesn’t mean it’s sound science or the standard of care. You have to ask questions calmly and you have to be willing to listen to the answers without letting emotion get in the way. If you’re letting anecdotes guide your medical choices, you’re not looking at the situation rationally and demanding proof. 


We need to embrace skepticism, and all the critical thinking tools at our disposal, in order to make good decisions, sound decisions, rational decisions for ourselves and our family members. If we can’t do that when deciding on how to treat our children’s colds and earaches and what preventative care we should use, then how will be able to do that when our child is seriously ill, potentially dying, and our decisions must be deliberate and rational? If you can’t think critically on an easy day where it doesn’t matter, how will you manage it when your life or your child’s life does?


In writing about the vaccine fears, Daniel Gardner,  in The Science of Fear, page 107 wrote:


 “The danger here is that we will collectively cross the line separating skepticism from cynicism. Where a reasonable respect for expertise is lost, people are left to search for scientific understanding on Google and in Internet chat rooms, and the sneer of the cynic may mutate into unreasoning, paralyzing fear. The end state can be seen in the anti-vaccination movements growing in the United States, Britain, and elsewhere. Fueled by distrust of all authority, anti-vaccination activists rail against the dangers of vaccinating children (some imaginary, some real-but-rare) while ignoring the immense benefits of vaccination – benefits that could be lost if these movements continue to grow.”


I don’t presume that I knew medicine better than the hematologist who reacted knee-jerk without considering the relative risks. I don’t. Obviously. What I did know better that day, though, and in the subsequent time period of calmly convincing her that the numbers didn’t support her treatment plan, was that ultimately, the buck stopped with me. I had to live with the decisions I made regarding my son’s medical care and I had to do so with the most accurate, the best of, information. I am his mother and his legal guardian. I make the decisions he cannot make for himself and I have an obligation and a duty to do it well, to get it right. Fear gets in the way of that. 


What I have to fall back on in times of crisis is critical thinking skills, a whole bunch of tools to help me make the best decisions I can with the information I have. 


You should not decide to vaccinate or not to vaccinate based on anecdotes. You should not be swayed by anecdotes relating autism to vaccine injury, nor should you be swayed by stories of vaccine-preventable deaths. Anecdote doesn’t give you the numbers. It gives you fear.


Sometimes you have to roll the hard six. Make sure when you do, you have the numbers behind you. What are the relative risks? Which is less risky? For some individuals, vaccines are too risky. These people rely on herd immunity. For most of us, the relative risks are less with vaccines than without. 


Say what you will about Penn and Teller, but their throwing balls at pins was an effective demonstration of relative risks. You have to decide do you have the balls, all of them, and can you effectively juggle them. Because if you’re wrong, if you’ve gone with anecdote over science, you may have live with some spectacularly crappy results instead of shooting craps.

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