This blog has been highly critical of evidence, taking every opportunity to strike at any vulnerability of a trial or research program. That is because this is serious business. Lives and limbs hang in the balance, pharmaceutical companies stand to gain billions from "successful" trials, investigators' careers and funding are on the line if chance findings don't pan out in subsequent investigations, sometimes well-meaning convictions blind investigators and others to the truth; in short, the landscape is fertile for bias, manipulation, and even fraud. To top it off, many of the questions about how to practice or deal with a particular problem have scant or no evidence to bear upon them, and practitioners are left to guesswork, convention, or pathophysiological reasoning - and I'm not sure which among these is most threatening. So I am often asked, how do you deal with the uncertainty that arises from fallible evidence or paucity of evidence when you practice?
I have ruminated about this question and how to summarize the logic of my minimalist practice style for some time but yesterday the answer dawned on me: I practice medicine like I invest in stocks, with a strategy that comports with the data, and with precepts of rational decision making.
Investors make numerous well-described and wealth destroying mistakes when they invest in stocks. Experts such as John Bogle, Burton Malkiel, David Swenson and others have written influential books on the topic, utilizing data from studies in economics (financial and behavioral). Key among the mistakes that investors make are trying to select high performers (such as mutual funds or hedge fund managers), chasing performance, and timing the market. The data suggest that professional stock pickers fare little better than chance over the long run, that you cannot discern who will beat the average over the long run, and that the excess fees you are charged by high performers will negate any benefit they might otherwise have conferred to you. The experts generally recommend that you stick with strategies that are proven beyond a reasonable doubt: a heavy concentration in stocks with their long track record of superior returns, diversification, and strict minimization of fees. Fees are the only thing you can guarantee about your portfolio's returns.
For the practice of critical care medicine, I have come to focus on three things:
- Use of Category 1 therapies whose benefits are so obvious as that is is not ethical to trial them (e.g., parachutes for gravitational challenge, antibiotics for sepsis, insulin for DKA).
- Use of Category 2 therapies which are supported by robust evidence of efficacy, with minimal risk of bias, i.e., those that pass the highest standards of scrutiny. In this class, there are very few therapies, e.g., low tidal volume ventilation, which pass this standard especially since the prior probability of efficacy in critical care appears to be low. (And it is no wonder to me that low tidal volume is probably efficacious because it is essentially doing the minimum of something, avoiding associated harms.)
- Strict minimization of fees. I consider that just about anything that I do, almost any drug or therapy I administer has fees, small but finite and additive little costs, whether they be from phlebotomy, nocebo effects, drug-drug interactions, subtle or serious side effects. To be willing to incur fees, I need good evidence that they are worth it. If that evidence is flimsy or does not exist, the only thing I can do is avoid the fees, and gratuitous complexity.
- drotrecogin-alfa: bleeding, cost, complexity
- Intensive Insulin Therapy: fluid, phlebotomy, fingersticks, anemia, hypoglycemia, death, complexity
- Stress Ulcer Prophylaxis: C. Diff, pneumonia, thrombocytopenia, drug interactions, complexity, rebound symptoms on withdrawal, or chronic use post-discharge from mindless continuation
- Early Goal Directed Therapy: fluid overload, central lines, dobutamine, transfusion, chasing lactates, cost, complexity
- daily labs, x-rays, and electrolyte replacement: phlebotomy, anemia, cost, complexity, disrupted sleep, nursing distractions, more phlebotomy, harmful cascades, willful neglect of prior probabilities