The 'July effect': Why experienced doctors may not deliver the best care

July is when medical trainees are most inexperienced.

Story highlights

  • Because of the academic calendar, July is when medical trainees are most inexperienced
  • Doctors' experience can allow them to pick up on symptoms or determine the right treatment
  • But experience can backfire because of cognitive biases and false heuristics
  • The biases can lead to the wrong treatment or a wrong diagnosis
"Don't get sick in July."
This is a common refrain in teaching hospitals. It's driven by the academic calendar: July is when the new interns — fresh out of medical school — start work. It's also when the senior trainees, the residents and fellows, graduate to supervisory, self-managed patient care roles.
In other words, it's when everyone is most inexperienced. The worry is that this inexperience leads to mistakes.
But what is less clear is how a doctor's experience influences the quality of their care. On its face, it makes sense that the longer a doctor practices, the more expertise she gains — which means better care for you.
But, in reality, it's not that simple.
Say, for instance, your doctor tells you: "In my experience, this antibiotic works great for sinus infections." Fair enough. It may also be completely true from your doctor's perspective: When she has prescribed antibiotics in the past for sinus infections, patients got better. But statements like this make us cringe, for two reasons.
First, as it turns out, antibiotics don't actually work for most sinus infections. In a large study published in the Journal of the American Medical Association earlier this year, people with sinusitis were randomly assigned to take antibiotics or a placebo. People treated with antibiotics did no better than those who got the sugar pill. The reason that bacteria-killing antibiotics don't help when you have sinusitis is because the infection is almost always caused by a virus.
The second — and perhaps more cringe-worthy — part is the summoning of the phrase "in my experience" as the major reason to prescribe the drug.
In the case of sinus infections and antibiotics, doctors' experiences (and those of patients) support the wrong decision. Here's why: The natural course of most sinus infections is to resolve on their own over time. People tend to go to the doctor — and get their antibiotics — when they are at their sickest. So they and their doctors falsely attribute their improvement to the antibiotic pills. Here, experience gets in the way of the right medical decision, which is to avoid antibiotics in the first place.
So let's get back to the July effect and the inexperienced, error-prone interns.
On one hand, some studies suggest that the July effect is a myth: A recent study examining 10 years of data on patients undergoing neurosurgery showed that July was no more dangerous than other months. On the other hand, reports have found that July patients do indeed fare worse: In a study of patients undergoing surgery for spine-related cancer, July patients were more than twice as likely to have a surgical complication and 81% more likely to die, compared with August or June patients.
A recent systematic review of all the research done on the topic concluded that many of the studies showing no July effect had small sample sizes and were not rigorously done, but the bigger and better investigations leaned toward finding that July is truly a more dangerous month in teaching hospitals.
So is medical experience good or bad?
Well, in most cases, your doctor's experience is very helpful, allowing her to pick up on a very subtle symptom early in a disease process, for instance, or to determine the right treatment when your condition falls outside of what is taught in textb