Snowball in a Blizzard Read online

  Copyright © 2016 by Steven Hatch

  Published by Basic Books,

  A Member of the Perseus Books Group

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  Library of Congress Cataloging-in-Publication Data

  Names: Hatch, Steven, 1969–, author.

  Title: Snowball in a blizzard: a physician’s notes on uncertainty in medicine / Steven Hatch.

  Description: New York: Basic Books, a member of the Perseus Books Group, [2016] | Includes bibliographical references and index. | Description based on print version record and CIP data provided by publisher; resource not viewed.

  Identifiers: LCCN 2015042274 (print) | LCCN 2015041457 (ebook) | ISBN 9780465098576 (eb)

  Subjects: | MESH: Diagnosis. | Uncertainty. | Health Policy.

  Classification: LCC RC71 (print) | LCC RC71 (ebook) | NLM WB 141 | DDC 616.07/5—dc23

  LC record available at http://lccn.loc.gov/2015042274

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  FOR MY MOTHER AND FATHER

  sorry, Pops, wish I coulda got it done sooner

  Contents

  Author’s Note

  Foreword

  Introduction

  1Primum Non Nocere: The Motivations and Hazards of Overdiagnosis

  2Vignette: The Perils of Predictive Value

  3Snowball in a Blizzard

  4The Pressures of Managing Pressure

  5Lyme’s False Prophets: Chronic Fatigue, Tick-Borne Illness, and the Overselling of Certainty

  6The Origins of Knowledge and the Seeds of Uncertainty

  7The Correlation/Causation Problem, or Why Dark Chocolate May Not Lower Your Risk of Heart Failure

  8“Health Watch”: Hype, Hysteria, and the Media’s Overconfident March of Progress

  9Conclusion: The Conversation

  Acknowledgments

  Appendix: A Very Nonmathematical Description of Statistical Significance

  Bibliography

  Index

  Confusion + Science = Answers*

  *Answers may require years of studying (real studying, not humanities studying) to be understood and will be expressed in terms of probability rather than absolute certainty.

  —C. G. P. GREY

  The diagnostic enterprise hinges on an optimistic notion that disease is part of a natural world that only awaits our understanding. But even if this is true, nature gives up its secrets grudgingly, and our finite senses are in some ways ill-suited to extracting them.

  —GARY GREENBERG

  Author’s Note

  THIS BOOK IS A SURVEY OF THE LANDSCAPE OF UNCERTAINTY IN MODERN medicine. My goal is to give the reader a sense of the challenges that can be found in all areas of medicine, which means that I cover a broad swath of topics ranging from cancer to women’s health to cardiovascular disease to infectious disease and others besides. Because I want people to see the thread connecting these topics, I can’t give comprehensive explanations about each of the issues I’ll touch on. One could write a very long and engaging book about mammography; here I’m going to discuss it in a few thousand words just to give you a sense for the underlying data and why people have interpreted the utility of mammograms in contradictory ways, which has led to dueling recommendations for its use.

  Specialists reading this may throw their hands up in frustration over what they perceive to be oversimplifications of particular studies, as well as an anemic bibliography. Perhaps I am guilty as charged. My hope is that by actually taking data straight off the journal page and putting it in front of readers, but doing it in a selective manner so it is framed by explanations helping them to make sense of it, they will have a sense of how the process works and will find medical research a little less mystifying.

  Too often academics are chided by their colleagues for attempts at popularizing their field, which by necessity requires stripping away some of the layers of complexity. I have found far too many scholarly books whose topics look interesting but are written in Academicish, leaving lay readers to struggle with impenetrable language or heaps of detail that obscure the main point. I will endeavor to find that sweet spot where readability and scholarliness overlap. In doing so, I hope to provide readers with a nodding acquaintance on human-subjects research, with the understanding that there is more to the story on any of the topics about which I’ll write.

  An additional disconnect between academics and the general public involves citations. In academia, you can’t even take a pee without providing seven references on who was the first person in that restroom, what studies have been done on the traffic of the restroom, research on the flushing dynamics, et cetera. Because our careers are tied to making observations that nobody else has made before, we’re understandably a bit jumpy when people take credit for our work inappropriately, so we’re very careful to attribute every assertion.

  My impression is that lay readers are far less interested in this citation game. Personally, I hate reading a book with footnotes (especially when they’re at the end of the chapter, which makes me have to flip back and forth) only to discover that a given footnote is just a reference when I thought it might be an aside providing further illumination on the topic in question. However this is a book about a very highly academic field, so I’ve settled on a compromise where footnotes are brief digressions, and references can be found in the bibliography. I won’t, however, offer up specific citations to those references in the text. This may make the occasional academic apoplectic, but it can’t be helped.

  Throughout much of the book, I use the term “doctors” and “physicians” to describe many different kinds of people, not all of whom are doctors or physicians. In many parts of the country, nurses now have wide latitude in making medical decisions and some have as much independence as full physicians. Additionally, the rise of the physician assistant (PA)—a title that sounds like they have less training than nurses when in fact they have more, occupying a true middle ground—has introduced a whole new type of health-care provider to medicine, and they typically make medical decisions indistinguishable from those of their physician colleagues. I therefore use “physician” and “doctor” as convenient umbrella terms to refer to all these professionals in the interests of not burdening the reader with a more accurate but distracting description. I apologize in advance to my nursing and PA colleagues for the shorthand.

  For the most part, this book is not a chronicle of my personal experiences as a physician, and as such it does not focus on patients I have encountered. The one exception is in the chapter on Lyme, in which I discuss a patient named David Marsh. David is not an “actual” patient but is rather a composite of many patients I have seen over several years as part of consultations on Lyme. No former patient of mine should fear that I am exposing their lives in some easily identifiable manner on the printed page.

  As noted in the Acknowledgments, I am grateful to many colleagues who have provided their insights in areas beyond what modest clinical expertise I possess. If I have made any penetrating or illuminating observations in this book, the entirety of credit should go to them. But any inaccuracies, misrepresentations
of fact, or failures of communication are due to me and me alone. I have endeavored to paint a picture of what I think is a critical problem in medicine today, but if I have not succeeded in this task, I humbly ask the reader’s forgiveness.

  Newton, Massachusetts, and Monrovia, Liberia, July 2015

  Foreword

  IT IS COLD AND RAINING OUTSIDE THE HOSPITAL—TYPICAL FOR THIS TIME of year. Rounds are about to start in the Intensive Care Unit. It’s going to be a long day, as the unit is full. There are many tests that will need to be ordered and reviewed, many treatment options to consider, and many conversations with patients and family members that will need to take place. The charge nurse calls for the team to gather: the lead attending physician, the nurses, the pharmacist, the social worker, a medical resident. The difficult business of tending to patients on the edge of life is beginning its daily cycle.

  The first stop is the room of a seventy-year-old woman who came to the emergency room with abdominal pain. Her symptoms began a little more than a day before she called the ambulance and got progressively worse during that time. By the time she came to the ER the night before, she was pale, and her skin was cool and clammy. Her blood pressure was low, which is why she was sent to the ICU.

  Now, twelve hours later, her pressure continues to remain low, and she has been given special medications called “pressors” to boost it. She is awake but drowsy, and she doesn’t respond much to questions. The team sweeps in and gathers around the bedside, looking over the paper chart, logging in to the portable laptop computer to review the labs, Shuffling around to accommodate the group in the small space.

  The patient’s daughter and husband sit nearby. They are not asked to leave.

  The medical resident summarizes the case for the team. Since coming in to the hospital, the patient has been given fluids and antibiotics. The resident explains that the on-call radiologist performed an abdominal ultrasound the previous evening.

  “Why didn’t we get a CAT scan?” the attending physician asks.

  “Her creatinine was 1.4,” the resident responds. “They wouldn’t give her the contrast.”

  “So what did it show?”

  “Normal bowel gas pattern, liver looked okay, not much else.”

  “Do we know why her kidney function is so low?”

  “No, we don’t,” says the resident, who then offers a few thoughts as to what might be the cause and how it might be worked up. “I think if she doesn’t improve, then we should call radiology and push for the CAT scan.”

  “We could throw her into ATN,” the patient’s nurse observes. “And it may not help us with the diagnosis.”

  None of this technical language is translated for the family, and the team doesn’t stop to unpack the subtleties of the diagnostic dilemma. This is rounding as it’s been done for generations in medicine: a highly specialized, fast-paced discussion to consider what is going on and what more needs to be done to restore a patient to health. What makes these rounds unusual is that this discussion is taking place directly in front of the family. There is no attempt to make it anything other than what it is, so the family has a direct window on how the team “really” functions. And although they have understood little of the jargon being bandied about, they heard the phrase “no, we don’t” quite clearly and understood exactly what that meant.

  The discussion continues for several more minutes. They examine the patient, itemize the various issues involved in her care, and formulate a detailed plan for the day. At the end, as the team readies itself for the next patient, the attending physician turns to the husband and daughter and explains, this time in the language of laypeople, the plan, which mainly revolves around finding the cause of the pain and the low blood pressure. Finally, he asks if they have any questions.

  “So, you don’t know why she’s sick?” the daughter asks.

  “Right now, I’m not sure.”

  “And you think it’s a good idea to get this CAT scan, or not?”

  “At the moment, I’m not sure. I want some more tests to return before I decide on that. Normally the CAT scan in this case is the best test we could order, but with her that carries some real risk, mainly because of the fact that the contrast we use can damage the kidneys, sometimes irreversibly.”

  “Do you think she needs antibiotics?”

  “Yes. Of that, I’m pretty sure, at least until we have some other explanation that would clearly indicate we can safely stop them.”

  And with that, the team leaves.

  What this family just witnessed was a discussion in which they heard the phrases “we don’t know” and “I’m not sure” more than once. To some laypeople, that may smack of clinical incompetence or cluelessness, but actually such phrases are common currency in medical rounds. Nothing about this example is particularly unusual. Patients with unknown conditions and diagnostic dilemmas like hers are medicine’s daily bread. Yet, far from creating anxiety and distress, the husband and the daughter are satisfied with the care she is receiving, and the frank admissions of uncertainty leave them more confident in the team than they would be if they had not been allowed to observe rounds in its unadorned state.

  The example is fictitious.

  But this ICU, where doctors and nurses and other health professionals openly confess to uncertainty, in plain sight of patients and families, is real.

  INTRODUCTION

  There are known knowns; there are things we know that we know. There are known unknowns, that is to say, there are things that we know we don’t know. But there are also unknown unknowns; there are things we do not know we don’t know.

  —SECRETARY OF STATE DONALD RUMSFELD, 2002

  How do we know that medicines work? How do we know that a blood test can unlock the mysteries of the body or that eating a particular diet may allow us to live longer? For instance, everyone knows with the kind of certainty that the earth revolves around the sun that smoking causes lung cancer, even though many of us have witnessed firsthand smokers who lived to old age as well as nonsmokers cut down by the disease. So why are we so confident of the harms of smoking? What allows public health officials to take to the airwaves and make that pronouncement with such certainty? Certainty brings a sense of comfort, but we do not often consider how we arrived at it.

  Many of us take for granted that we live in an age of medicine where, to put it quite simply, we know what we are doing. We can read about common treatments for ailments that afflicted people in previous centuries and think to ourselves I’m sure glad I didn’t live in that time. We look back at the confidence that European doctors had in bloodletting, purgatives, and poultices of dung with horror; we see the faith of healers around the world in herbal remedies that we know are no match for our knowledge of biochemical molecular mechanics, which forms the basis of what we now call rational drug design.

  If you had to ask someone who knew a little of the history of medicine about when it became modern, they’d say the transformation took place over about fifty years spanning the late nineteenth and early twentieth centuries. They would cite early precedents that indicated change was soon to come, like the creation of that ubiquitous tool of medicine, the stethoscope (1816), the dawn of modern anesthesia at Massachusetts General Hospital (1846), John Snow’s detective work on cholera in London that basically founded modern epidemiology (1854), and so on. But the development of biochemistry by the 1880s, with its increasingly sophisticated ability to identify, purify, and even synthesize physiologically active compounds, really marked the turning point for medicine as a scientific discipline. This was followed in quick succession by the discovery of X-rays in 1895 and the development of the EKG in the early 1900s, which we still use today almost exactly as we did then. Everything that came before these advances was largely quackery, and everything after, largely rational.

  This is, of course, an imagined generalization, as well as an oversimplification, but I don’t think it stretches credulity to suggest that many people harbor some kind of n
otion like this about medicine. During the twentieth century, they would say, medicine could finally stand alongside its “harder” brethren of physics and chemistry and claim to be modern without a trace of irony. The reason we would allow ourselves to be subject to the ravages of some phenomenally toxic treatments for, say, pancreatic or bone marrow cancer, and regard equally toxic treatments doled out in 1750 for dropsy as something just short of manslaughter, is because we know that the cancer treatments can prolong life. We have science to shed light on the situation, and science not only separates the wheat from the chaff, but it invents new treatments by its intimate knowledge of the body at the molecular level, and not by running off into the forest gathering nuts and leaves helter-skelter, administering them to patients in an equally random manner.

  Make no mistake, this depiction of medicine has much truth behind it. The advent of biochemistry really did allow for much more highly effective treatments, and early radiology set the stage for a quantum leap in the quality of diagnoses over the next several decades. Moreover, this period saw the rise of regulatory agencies that forced drug manufacturers to market their products based only on narrow indications for the diseases they could prove to treat, and state laws gave physicians and apothecaries rigorously trained in the sciences an almost complete monopoly on the business of healing. At the dawn of the Republic, pretty much anyone, anywhere in the United States, no matter their level of education and scientific training, could hang up a shingle, call themselves “doctor,” and treat patients in whatever way they saw fit. Yet in the age of modern medicine, about the past hundred years, if one did this without possessing the proper credentials, one would likely face jail time.

  Since the beginning of this modern period of medicine, the advances have come with ever-increasing speed, in nearly every aspect of practice: breakthroughs in microbiology, in pharmacology, in surgery. In his signature work, The Greatest Benefit to Mankind, the eminent historian Roy Porter attempts to compress the entire history of medicine into a single volume.* The first half of the book, fully 350 pages of dense text, is devoted to the first 5,000 years of the profession, including chapters on early Chinese and Indian medicine. The second half of the book, by contrast, covers just the past 200. It is an unmistakable message: some stuff was interesting in medical antiquity, but it was mostly a minor attraction until somewhere after 1800, and the show really got going the century after that.