The action was taken in response to concerns that lengthy hours left residents tired and prone to making dangerous medical errors.
But others have expressed concern that decreased continuity of care would have negative effects on patient outcomes.
For the first study, Volpp and his colleagues looked at more than 8.5 million Medicare patients admitted to 3,321 teaching hospitals from July 1, 2000, to June 30, 2005. The patients had been diagnosed with heart attack, congestive heart failure, gastrointestinal bleeding or stroke, or were undergoing different types of surgery.
Overall, the changes in work hours made no difference in the odds of dying.
But since the reforms were implemented, the most teaching-intensive hospitals (those with a large percentage of residents) had a 0.42 percent absolute increase in death rates for patients with one of the medical conditions and a 0.05 percent absolute increase in death rates for surgical patients, compared to non-teaching hospitals (no residents). Neither increase was considered statistically significant.
The second study looked at more than 300,000 patients admitted to 131 acute-care VA hospitals between July 1, 2000, and June 30, 2005, with the same constellation of diagnoses as in the first study.
By the end of the second year of the new work rules, the risk of dying decreased significantly in more teaching-intensive hospitals for the medical patients but not for the surgical patients.
"I think there are a couple of key reasons why we may have observed these significant improvements in VA but not non-VA settings," Volpp said. "The VA [hospitals] are more teaching-intensive, so you might expect that if there are beneficial effects, that those effects might be bigger in VA hospitals."
"A second reason is that work intensity is generally believed to be lower in VA hospitals than non-VA hospitals. In other words, res
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