Sunday, August 21, 2011

Decision Fatigue. For doctors, too?

This article by John Tierney in the New York Times suggests that humans suffer from decision fatigue, the tendency to make worse decisions as you make a series of hard decisions as the day goes along.  Here are some pertinent excerpts:

No matter how rational and high-minded you try to be, you can’t make decision after decision without paying a biological price. It’s different from ordinary physical fatigue — you’re not consciously aware of being tired — but you’re low on mental energy. The more choices you make throughout the day, the harder each one becomes for your brain, and eventually it looks for shortcuts, usually in either of two very different ways. One shortcut is to become reckless: to act impulsively instead of expending the energy to first think through the consequences. The other shortcut is the ultimate energy saver: do nothing. Instead of agonizing over decisions, avoid any choice. Ducking a decision often creates bigger problems in the long run, but for the moment, it eases the mental strain. You start to resist any change, any potentially risky move. 

Once you’re mentally depleted, you become reluctant to make trade-offs, which involve a particularly advanced and taxing form of decision making.

“Even the wisest people won’t make good choices when they’re not rested and their glucose is low,” Baumeister points out. That’s why the truly wise don’t restructure the company at 4 p.m. They don’t make major commitments during the cocktail hour. And if a decision must be made late in the day, they know not to do it on an empty stomach. “The best decision makers,” Baumeister says, “are the ones who know when not to trust themselves.” 

All of this led me to wonder whether there is any evidence that there is a higher rate of medical errors later in the day, after doctors have made dozens of decisions.  So, in tune with the times, I crowd-sourced the question, posing it this way on Twitter and Facebook:  "Query: Has anyone seen studies linking surgical error rate to the time of day?"

Bobby Ghaheri, MD (@DrGhaheri) tweeted, "That's why I insist on operating in the morning."

Braden O'Neill (@BradenONeill), an MD student in Calgary, searched the NIH literature and responded:  "There has been some work on time of day and surgical outcomes but it seems more about the cases themselves."  The article he cites does have some interesting conclusions, but is not supportive of my hypothesis:

After adjustment for patient and procedure characteristics, mortality had a moderately strong association with start time, but only for nonemergency cases starting 9:30 pm to 7:30 am. As for morbidity, after adjustment, operations starting 9:30 am to 1:30 pm and 5:30 pm to 9:30 pm were associated with a weakly elevated risk of morbidity, but those starting 9:30 pm to 7:30 am demonstrated a strong effect on morbidity.. Subgroup analysis showed this effect was largely a result of elevated risk of morbidity in emergency cases from this overnight time period.

David Rosenmann (@DavidRosenman) from Mayo Clinic noted: "A 2011 study suggested increased maternal morbidity when unscheduled cesarean sections took place at night."  But that may not help, in and of itself, because we don't know if the doctors handling those cases have been through many during the day, or whether it is a fresh crew.

Over at Facebook, transplant surgery fellow Kristin Raven reported, "The time of day organ transplants occurs is known not have any effect on outcomes."

A medical colleague who responded to an email supported Kristin's finding:  Surgery is interestingly less intense than clinic -- people are more complicated than bodies. So no consistent findings have emerged except that emergencies/late night cases have poorer outcomes, which is not a surprise. 

A few minutes later, he elaborated:  I should correct to say that it depends on the operation -- routine feeding tube placement vs Whipple -- and the clinic -- breaking bad news about a concern vs routine well baby visit. This is the complicated nuance about medical decisions that exists just as the nuance about financial decisions the article talks about matters.

Meanwhile, engineer Roberta Brown noted, "There are some solid safety statistics about the most likely times for accidents. If I remember properly, it's the half hour after lunch or a break."

But, pathologist Beverly Rogers suggested that I was probably asking about the wrong specialty:

This is a problem for pathologists too, and actually that would be a better measure - surgical error rates could be due to physical fatigue or other factors not related to decisions, whereas pathology or other diagnostic error is clearly related to decision-making (as well as interruptions, and other cognitive errors.)

I am left thinking that Beverly raised the question in a better context than I did.  We would need to look at specialists who need to make several difficult decisions in a row.  For example, here would be the hypothesis to test:  As pathologists look at dozens of tissue samples during the course of the day, making explicit decisions as to whether the cell patterns are evidence of disease, does their percent of positive findings change as a function of time of day and/or the number of cases reviewed?

Tierney describes an element of decision fatigue in terms of "crossing the Rubicon."  He notes:

The experiment showed that crossing the Rubicon is more tiring than anything that happens on either bank — more mentally fatiguing than sitting on the Gaul side contemplating your options or marching on Rome once you’ve crossed. As a result, someone without Caesar’s willpower is liable to stay put.  Part of the resistance against making decisions comes from our fear of giving up options. The word “decide” shares an etymological root with “homicide,” the Latin word “caedere,” meaning “to cut down” or “to kill,” and that loss looms especially large when decision fatigue sets in.

It would indeed be fascinating to know whether, notwithstanding their exceptional training, medical specialists like pathologists display any such patterns of behavior.  And, in the case of pathologists, would "not crossing the Rubicon" lead to more positive findings or fewer?

Perhaps this offers a research opportunity for a rising medical star.


Pam Ressler said...

From Google+:

Really interesting discussion, Paul. I see this as an important discussion for nurses as well. Is there a difference in decision fatique in longer shifts (10-12 hour) versus more tradional (8-hour) staffing?

Steven Davidson said...

From Google+:

There's data on emergency physician clinical productivity by shift length showing that after seven hours productivity begins to decline and falls off still more after nine hours. Prior to Tierney's piece I think many of us thought of this issue as a combination of physical fatigue and generic "mental fatigue." Tierney and the research cited offer a paradigm for evaluating decision fatigue.

I see +Pam Ressler got in just ahead of me on the nursing issue. Reminds me of a nursing strike at my hospital in the late 1990's that was all about 8 hour vs. 12 hour nursing shift.

Anonymous said...

It is the same for nurses too. As a CRNA I would find, while being on call, that after working 16 hours I felt mentally and physically fatigued.

I would have a difficult time concentrating. What I was thinking of was I hope we finish soon and I get to rest.

This was a rarity in a community hospital but it did happen.

David Russo said...

There should be a time at work when you can take a short nap.

Anonymous said...

There are certainly anecdotal cases of radiologists diagnostic errors increasing as the day wears on, and we have collected many such examples. I certainly know when my concentration is reduced and turn to more menial tasks that are not so concentration-dependent. Another well known radiology example is the radiologist who reads hordes of screening mammograms – certainly the ability to focus diminishes with time and some practices now limit this time and switch the reader to other tasks, such as performing ultrasounds or procedures. From my own experience, I cannot endure an entire day of reading/teaching/dictating diagnostic CT scans and now split the day with ultrasound which is a higher volume less intense environment.

Paul Levy said...

Interesting, but not quite what I am asking. Does the NATURE of the diagnostic decisions change as you make more decisions?

Anonymous said...

Unfortunately, some of what you have cited is junk science, and some of it ignores basic biology, but some of it is correct.

The junk science is the concept of low glucose late in the day. No truth to that. Glucose does not fall as the day progresses, and the level of brain function is not dependent upon level of blood glucose across a wide physiological range.

The basic biology is that different people have different parts of the day or night when they hit their peak performance. This is a biological trait that is genetically determined.

Many people are larks (the ones you cite in your article) who are wide awake in the morning, and peter out as the day progresses. People who work like this tend to migrate toward fields like surgery where this is necessary. Many other people (and virtually everyone between the ages of 18 and 25!) are owls, who do their best work late in the day, but have a hard time getting started or producing useful work early in the day.

The part that is correct is that for all people, the longer you stay awake, the greater your physiological sleep deficit, and the tendency for you to become less alert. This seems to become critical at about 17 hours, and there is strong evidence that cognitive performance and ability to avoid auto accidents begins to fall off when you go beyond this 17 hour limit or when you are working during the “night” of your own circadian day. (If you wake up habitually at 6am, this would be after 11pm, but if you wake up at 11 am, this would be after 4am).

That is why the new ACGME work rules for resident avoid working more than 16 hours at a time, especially when the latter part of that would come during the circadian off-period (the typical pattern for interns who come in at 8am and then are on call overnight).

Paul Levy said...

Thanks very much! What about the question I raise above, which is the conclusion of the Tierney article: Does the NATURE of the decisions change as you make more decisions?

Beverly said...

From Facebook:

I think sometimes we don't study what we don't want to know.

Anonymous said...


I understand your question but I am not sure, in medicine, that it can be answered in analogous fashion to the parole board example. In medicine there is no 'safe' default diagnosis - you can do harm just as surely by calling every mammogram or pathology slide benign as you can malignant, if either is wrong.
I would bet that in medicine, as the decision fatigue piles up, the default position would be to delay a decision - order more tests, ask for recuts on the slides, etc. - as an unconscious excuse to put off a decision. I can't see any other no-fault way to do it, short of altering your work schedule as anon 6:55 indicates.

nonlocal MD

Anonymous said...

Potentially useless note: The two days I've been most exhausted mentally have been the days I moved into a new home. These are small, insignificant, and easily reversible decisions -- but facing so many in succession leaves me wiped out.