Maybe you dreaded the encounter, wondering if that extra piece of cheesecake - consumed against the counsel of your stern inner food-guardian last week - might tellingly manifest to the physician-detective in your blood pressure, weight or blood sugar reading. Maybe you went because you ran out of your medication - and exhausted that convenient telephone-refill option where you didn't have to see anyone in person, darn it! Maybe it you needed a quick fix for something urgent - a rash, a nagging ache, a high fever. Or maybe you went because you actually like going to the doctor...and it'd been a while, and you want to be proactive about your health. (And you also eat 6 servings of vegetables daily, file your income tax return several months before it's due, stick to a grocery list and never lose pens. We physicians tend to love you.)
Your doctor probably saw you, was hopefully pleasant and cordial, maybe clucked a little bit at your still-high blood pressure or lab tests, adjusted some medications, perhaps asked you how life was going. Maybe reminded you to lose some more weight, stop smoking, eat better. You nodded and maybe squirmed, remembering that dinner date at the fondue restaurant you have on Friday.
And done - no more doctor visits for another year, phew!
But have you ever wondered: how, exactly, do we know what needs to be done to fix your symptoms?
In other words: why is it that sometimes, you feel absolutely lousy, with aches and pains everywhere and just know you need an antibiotic to make this go away, and your doctor tells you to take Tylenol and return if things don't get better? Or, why, when you go visit your doctor to check on that mild headache you've been having for a little while (mostly in the hope that your wife will finally stop nagging you), they order an immediate head scan and send you to a specialist?
Technically, the answer requires going to medical school (and is apparently worth an average $250,000 and change). But the basic recipe is not in fact that mysterious. Doctors base many of their decisions on the results of scientific studies, also known as "evidence-based medicine".
In the world of Western medicine, evidence-based medicine is King.
It's why, when Over-Enthusiastic Resident pipes up during rounds in the hospital with a suggestion to order a certain lab test or change an antibiotic for a patient (not that this happened to, say, me or anything), the attending raises an eyebrow and questions: "Really? What did the latest study show about that option?"
The studies usually have hokey - I mean, catchy - acronyms like ASPIRE, HOPE, POISE to increase Google-ability and promote easy recall, so that Know-It-All Resident (who carries the "Scientific Study Update Alert" app on his PDA and an e-mail account dedicated to late-breaking medical study news) can neatly chime in: "Well, Dr. Intimidating Attending, the UTOPIA trial showed that there was a 40% reduction in all-cause mortality when Drug Miracle was given compared to placebo." And the attending beams with satisfaction (while Over-Enthusiastic Resident wonders when she can sneak away to the nutrition room to grab graham crackers.)
EBM inspires a knee-jerk reflex. Discuss whether to order an x-ray, prescribe an antibiotic, take a multi-vitamin every day, get a prostate exam: "What does the evidence show?" On the flip side, appending the magic phrase "According to Widely Accepted Clinical Trial X," to your treatment plan highly increases the chance of being taken seriously.
EBM is how doctors know that when your cholesterol is a certain value, it's time to start the statin. It's how they know whether or not they should order an MRI for that low-back pain or just reassure you that it will go away. It's how they know the prognosis for a cancer, make a decision that women under 40 don't need mammograms, that the 3-year old with an earache doesn't need antibiotics.
The prevailing reign of Evidence-Based Medicine is why, sometimes, things that may seem like "common sense" to the general public are announced as ground-breaking findings on CNN. ( "New study shows that eating food reduces hunger," "Study suggests sleep-deprived residents make more mistakes in treating patients.")
This is mostly because sometimes, things that may seem like common sense to us aren't in fact borne out by EBM. ("Study suggests no benefit to daily multi-vitamin," or "Cancer patients practicing "positive thinking" do not have better outcomes, according to new study,")
The best studies analyze health outcomes over large groups of people, hopefully a group of people which are similar to the type of patients the doctor treats. (If the study group consisted of 90% African-Americans and few Asian people, you might wonder if the results of the study could apply as well to Asians.) When a well-designed study finds, for example, that patients with high cholesterol treated with a statin had a 50% reduction in their "bad cholesterol", that might motivate a physician to prescribe that drug for you when you have high cholesterol.
The best studies analyze health outcomes over large groups of people, hopefully a group of people which are similar to the type of patients the doctor treats. (If the study group consisted of 90% African-Americans and few Asian people, you might wonder if the results of the study could apply as well to Asians.) When a well-designed study finds, for example, that patients with high cholesterol treated with a statin had a 50% reduction in their "bad cholesterol", that might motivate a physician to prescribe that drug for you when you have high cholesterol.
(Warning: there are many, many caveats to interpreting studies - which will come in later posts. As a preview: statins are now the topic of some controversy - even though they are linked to reduced cholesterol buildup in arteries, not much evidence supports the notion that statins prolong life in patients who don't have known heart disease. In evaluating a study, one needs to ask: what health outcome matters most? Living the longest number of years? Avoiding a heart attack? Living a chest-pain/disability-free but maybe shorter life? Avoiding side effects of chronic medication, even if it means maybe increased chance of a heart attack? Controlling the lab test result to normal ranges? You get the picture....it's complicated.)
The key point is that the treatment for an individual patient is governed mostly on results seen in groups of people in studies - who may or may not be very similar to you. An intelligent physician will, of course, use 'clinical judgement' in deciding whether the results are relevant to your particular case. (Sometimes, well-meaning but very very insistent moms or siblings insisting upon an antibiotic will heavily influence this 'clinical judgement'.)
In fact, individualizing treatment is arguably where the true "art" and "skill" of medicine really lies. All physicians can read a study, but skilled physicians intelligently interpret the findings and know how to tailor treatment for a particular patient's case.
EBM can be a good thing: It reduces inconsistencies and impulsiveness from the process of treating patients (things you don't want in your rational, intelligent physician-treater). It lends external support and validation to our choices. It provides justification for why we make certain decisions. And it allows us to sort with logic through the maze of drugs, treatments, tests and options we have to make you feel better.
It can also be a less-than-good thing. For a rushed physician, EBM can become a substitute for thinking about you, individually - your personal situation and environment. (Example: if people in a study got better after taking a new drug every day for 6 months, but Patient X in the doctor's office just lost his job and might take the drug only once a week because he can't afford it, would the drug still work? Or could sporadic use even cause harm?) It can encourage "cookie-cutter" medicine. And if the studies that guide our decisions are incomplete, flawed, or suffer from conflict-of-interest issues, then health is potentially undermined.
This last point is troubling. Take Vioxx: a medication widely used and prescribed for pain and inflammation from 1999-2004 after selectively published studies (released by Vioxx drug manufacturer Merck) touted its purported effectiveness with fewer side effects. In 2004, the drug was pulled off the market after a study showed Vioxx may have provoked 27,000 heart attacks and deaths. Leaked emails and studies uncovered in the ensuing lawsuit revealed that that Merck executives had known about the troubling heart attack findings three years earlier - but had not released the data to the public.
Vioxx was the center of a major scandal, but truly frightening is the unpublicized subterfuge that is strikingly commonplace in medical literature. Take the practice of ghostwriting of medical studies, referring to "pharmaceutical companies secretly authoring journal articles published under the byline of academic authors." Often, authors of the article are listed as respected academic physicians from top-notch university medical centers- inspiring readers' trust in the quality of the study - but are actually written by pharmaceutical-company researchers. And policies against ghostwriting are strikingly sparse: A February 2010 survey in PLoS Medicine revealed that only 20% of the top 50 academic medical centers in the U.S. carry regulations or rules against ghostwriting. The result: fatal flaws in the objectivity of published research - those very studies that residents/medical students/experienced physicians/hospital staff use to guide their clinical decisions.
Digressions aside, how is this discussion of EBM relevant to public health?
First of all, public health training lays the essential skills for constructing high-quality, sound EBM on a population level. Public health training is centered on learning how to study disease patterns and study its effects, properly designing and conducting a clinical trial, and - crucially - how to interpret and analyze the results of a study published in a scientific journal and apply such results. Things that you would, ideally, want your physician to know well.
(Unfortunately, most physicians in the U.S. do not receive rigorous training in public health, apart from a cursory lecture or three during medical school, and maybe some exposure in residency if they seek it out. A troubling health issue in itself - but much more to come on that in a later post.)
But the second, crucial and likely counterintuitive point, is that public health actually inspires physicians to think about you as an individual. It inspires your treatment plan to be tailored to your circumstance, to your specific situation. It inspires the "art" of medicine.
Think carefully about this second point. Most people, if they happen to know what public health involves, will say "Public health is studying health of populations." Many public health students will say, "Public health is studying health of populations." Before I began studying at Berkeley, I said, "Public health studying health of populations."
I still say confidently that public health involves studying the health of populations. But in thinking and studying about health from a population angle, something happens.
It's the realization that treating disease successfully requires understanding the context of the individual.
Public health icon Dr. Roy Acheson - founder of Yale's department of chronic disease epidemiology and the Rockefeller Foundation's International Clinical Epidemiology Network - enunciated the crucial question of public health: "Why did this patient get this disease at this time?"
Here's a little example. Thousands of germs float around the air every day. The germs that cause coughs and colds will invariably end up on our hands, in our noses, maybe even inside our throats where they can multiply and produce that tell-tale scratchiness that leads to a full-blown cold.
But while some people come down with a cold, others with that same bug don't end up getting sick, even though that germ is nestled right where they could wreak mucus-y havoc.
It goes on. Some women with a gene for breast cancer won't end up getting the disease, while others with the gene will get breast and ovarian cancer before the age of 30. Someone who smokes for 80 years escapes lung cancer, while someone who smoked irregularly for 5 years dies of cancer after 2 months. Some people who take a drug for blood pressure respond immediately, while others are on 10 drugs.
What causes some people to get sick and not others? What causes some people with a gene to get a disease but not others; some people to respond to a surefire treatment and not others? Why do African American males die from cancer at nearly 75% higher rates rate than Hispanic males? Why are a greater proportion of poor people also overweight? Why do residents of Japan live nearly 20 years longer than Americans? Why is providing vitamin A supplements to Ugandans suffering from vitamin-A-caused night blindness not effective?
It all goes back to that question: "Why this patient, why this disease, why at this time?" Unlocking the answer requires linking the population health patterns evident in EBM to the "real-world", individual experience of disease. It is public health's central puzzle; figuring it out is an essential step in creating a prevention and treatment strategy that boosts health.
So now that you're hopefully on board with the public health parade, I'll continue to share insights here as I begin the lengthy task of cracking the health puzzle. As a preview to what's coming next: it turns out that the social and environmental factors play a larger role in disease than one ("one" meaning my naive pre-public-health self) might think.
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