What do I know?

Snowball In a Blizzard: A Physician’s Notes on Uncertainty in Medicine begins and ends with its author, Steven Hatch, a professor of medicine at the University of Massachusetts Medical School, urging doctors not to bully their patients. Hatch, himself a doctor, knows what he’s talking about.

In an episode related near the end of the book, Hatch recalls gathering with other family members after his father, afflicted with serious health problems, had collapsed. His father ended up in the intensive care unit of a hospital where he was t reated with something called a “hypothermia protocol,” involving cooling blankets. Hatch’s family turned to Hatch for an explanation. What was this protocol? Hatch himself, however, had to admit he had never heard of it. ( It was a very recent procedure.)

So much for Hatch’s special status as a fellow professional in this conclave of doctors and laity. He had to find out on his own what the implications were, and discovered the protocol’s use was, in his words, a “case study in un- certainty.” Far from bringing back the patient on his deathbed to anything like normality, it often left the patient lucky to be able to hold a toothbrush.

“Not one physician with whom our family spoke during this time ever made this clear,” he writes. Hatch and his family were not exactly bullied, but a reader can readily infer the vulnerability of a family member unversed in the mysteries of the healing profession. Under these circumstances, Hatch advises doctors to opt for what he calls “a frank admission of uncertainty.”

It’s hard to give up that illusion of certainty. We have all seen on television or movies the scene where the cancer- riddled patient asks his physician, “How long have I got, doc?” There was a time when oncologists tried to answer that question — but their prognoses were usually way off base, so eventually they stopped making them. Death has a way of not running according to schedule.

A more recent, and more controversial, instance of doctors and patients failing to emphasize uncertainty is captured by an episode Hutch recalls in which a fledgling radiologist talked about his career plans. He was going to do mostly “general radiology, a little bit of everything,” he told his colleagues. Then he added that he was going to avoid mammography. “It’s like trying to find a snowball in a blizzard,” he said, summing up the challenge of accurate interpretation of mammograms. But it also suggests the wider debate around mammography.

A 2009 study by a U.S. government agency — later supported by a highly respected Canadian study — maintained that screening mammography when used in the wrong context might actually be a danger to women. “This came as a splash of cold water to the public health community,” writes Hatch, “for many practitioners had been reared to think of screening mammograms as one of the most important life- saving technologies of modern medicine. The bottom line, however, was unmistakable: it was time to reconsider the practice of recommending annual mammograms for all women after age 40.”

The effects of screening women under 50 were simply t oo uncertain — t he younger t he woman screened by mammograms the greater chance of detecting early cancers but also the greater chance of false positives, that is, the indication of the presence of cancer where there was, in fact, none. The painful and devastating consequences of false positives — biopsies, mastectomies, chemotherapy and so on — at some point made screening mammograms a dubious proposition.

Hatch’s book takes aim against those who would deny uncertainty, but also mentions those who, for reasons of their own, deliberately foment uncertainty where there is certainty — the anti-vaxxers who believe vaccines cause autism in some children, the advocates for sufferers of Lyme disease in the U. S. who have converted, without reason or scientific analysis, what is in reality a treatable illness into a sinister malady, almost a metaphysical condition overshadowing their lives.

News media, in this survey of medical controversies, get their knuckles rapped — no surprise there. It’s hard to report on medical phenomena with the nuance due to the subject. For this reason, among others, a favourite genre among health reporters is the scary virus story, which doesn’t require all that much nuance. The all-time rare and scary virus is the Ebola virus, although the SARS virus not that long ago gave Toronto a run for its money.

Hatch never tires of mentioning that, yes, there is a frightening epidemic rampant in North America — but it’s not caused by some virus hatched in tropical Africa, but by the refusal of potential cardiovascular victims to eat less and exercise more. There’s no uncertainty about it.

In t he vast realms of medicine, such uncertainty is rare, however. Perhaps it may never be found. “Most data in the realm of medicine is inherently fuzzy,” Hatch writes. “Some diseases require only a single test whose results can be interpreted with high degrees of certainty, but many others require a careful consideration of several pieces of information, at least some of which can be contradictory.”

The principle of acknowledging uncertainty, where uncertainty exists, remains the guiding principle, or should be the guiding principle, of relations between doctors and patients. Whether to ask for a mammogram, or undergo another “stress test” in the cardiovascular section of the hospital, or employ the surgeon’s knife to remove cancers that may, if left to their own devices, never harm you at all are good questions, deserving careful consideration among equals.

Snowball In a Blizzard: A Physician’s Notes on Uncertainty in Medicine By Steven Hatch Basic Books 312pp; $36.50 IT’S HARD FOR DOCTORS TO GIVE UP THE ILLUSION OF CERTAINTY