Studies on the impact of work-hour regulations have been less than conclusive. A 2004 New England Journal of Medicine study, for example, found that interns working under a work-hours cap made fewer errors than did a similar group under a traditional system. But a Journal of General Internal Medicine study published the same year found no conclusive evidence that resident work-hour restrictions in New York improved outcomes among multiple patient groups.

"The fact that studies have contradicted each other indicates that it's not clear whether there is benefit or harm from the regulations," said Shetty.


Shetty teamed up with Jay Bhattacharya, MD, PhD, assistant professor of medicine with Stanford's Center for Health Policy/Center for Primary Care and Outcomes Research, to compare death rates in patients hospitalized in teaching hospitals before and after August 2003, one month after the rules went into effect. Using a nationally representative data set of hospital patients between 2001 and 2004, they looked at the clinical outcomes of 1.5 million adult patients, which included 1.3 million admitted for a medical diagnosis and about 200,000 admitted for surgery.

After running their analysis, the researchers determined that the regulations appeared to benefit medical patients: for every 400 patients admitted to a teaching hospital after the regulations went into effect, there was one fewer death than before. In other words, Shetty explained, "Before the regulations, 60 out of every 1,000 medical patients died. After the regulations, the number of deaths was 57 or 58 out of every 1,000."

The researchers also determined that the regulations did not appear to have an impact on surgical patients, a finding the authors called "striking." Shetty said there were several possible explanations: the smaller number of surgical patients may have limited the researchers' power to detect statistically significant differences. It's also possible, he said, that any errors due to fatigue may have been offset by transfer-of-care errors, or that the majority of errors occurred during surgery by attending physicians or senior residents - whose hours did not change appreciably under work-hour caps.

Shetty said more study is needed to clarify why there was no apparent impact on surgical patients and to pinpoint the source of the improvements seen in the other hospital patients. If that improvement resulted from shifting patients from inexperienced residents to more-experienced doctors, it could mean residents aren't obtaining sufficient experience and skills during training. In that case, "the regulations' long-term effect could be deleterious," the authors noted in the paper.