Residents' Shorter Work Hours Don't Affect Patients' Mortality

PHILADELPHIA, Sept. 5 -- Limiting the hours residents can work did not increase patients' death rates, as some had feared, nor did it save lives significantly, as others had hoped, according to two large national studies.

Moreover, a small mortality decrease for certain groups of medical patients, mainly those with acute MI, was found in one of the studies, Kevin G. Volpp, M.D., Ph.D., of the University of Pennsylvania here and the Philadelphia VA Medical Center, and colleagues, wrote in the Sept. 5 issue of the Journal of the American Medical Association.

In a national study of more than eight million hospitalized Medicare patients, there was no significant increase or decrease in mortality in the first two years after work hours were limited for residents, Dr. Volpp said.

In a second study of patients in acute-care VA hospitals, the same researchers found a small drop in mortality in the second year after work hours were curtailed. The decrease occurred among a limited group of patients with four common medical conditions, mainly MI, but also congestive heart failure, GI bleeding, and stroke.

Widespread concern abut the number of deaths in U.S. hospitals from medical errors prompted the Accreditation Council for Graduate Medical Education (ACGME) to implement duty hour regulations as of July 1, 2003. Work limitations for residents now include no more than 80 hours per week with one day in seven free of all duties, averaged over four weeks.

Also, the rules specify working no more than 24 continuous hours with an additional six hours for education and transfer care; in-house call no more frequently than every third night; and at least 10 hours of rest between duty periods.

The Medicare observational study included 8,529,595 patients admitted to 3,321short-term, acute-care nonfederal hospitals with different teaching intensity, with data from July 1, 2000, to June 30, 2005. Mortality was determined within 30 days of admission.

All Medicare patients had principal diagnoses of acute myocardial infarction, congestive heart failure, GI bleeding, or stroke or a diagnosis-related group classification of general, orthopedic, or vascular surgery. Results were adjusted for patient co-morbidities, common time trends, and hospital site.

Logistic regression was used to examine the change in mortality for patients in more versus less teaching-intensive hospitals before duty hour reform (academic years 2000-2003) and after duty hour reform (academic years 2003- 2005).

In medical and surgical patients, no significant relative increases or decreases in the odds of mortality for more versus less teaching-intensive hospitals were observed in either year one or year two after the work-hour change compared with pre-reform years.

Compared with the pre-reform years, in reform year one, for the combined medical conditions group, the odds ratio [OR] was 1.03; 95% confidence interval [CI], 0.98-1.07; and for the combined surgical categories group, the OR was 1.05; CI, 0.98-1.12.

In reform year two, for the combined medical conditions group, the OR was 1.03; CI, 0.99-1.08; and for the combined surgical categories group, the OR was, 1.01; CI, 0.95-1.08).

Compared with non-teaching hospitals, the most teaching-intensive hospitals had an absolute change in mortality from pre-reform year one to post-reform year two of 0.42 percentage points (4.4% relative increase) for patients in the combined medical conditions group and 0.05 percentage points (2.3% relative increase) for patients in the combined surgical categories group.

Neither of these increases was statistically significant, the investigators said.

The absence of a relative change in mortality among Medicare beneficiaries in more teaching-intensive hospitals may reflect lack of compliance with the duty hour rules, although, the researchers cited strong financial incentives for programs to comply to avoid loss of accreditation.

Among several possible limitations to this study, the researchers cited the lack of information on actual hours worked at each hospital. Even with the size of the Medicare population, some of the confidence intervals are still somewhat broad, they said, and small, possibly meaningful effects cannot be ruled out.

In the second study of 318,636 patients admitted to 131 VA hospitals with data from July 2000 to June 30, 2005, Dr. Volpp and his team examined the effect of work-hour reform in VA hospitals with different teaching intensities.

Just like the Medicare study, there was no overall improvement or harm for the VA patients, surgical or medical, but there was a small saving of lives after reform for patients with four common medical conditions in the second year of the study who were in teaching-intensive hospitals.

Comparing a hospital having a resident-to-bed ratio of one with a hospital having a resident-to-bed ratio of zero, the odds of mortality were reduced for patients with acute MI (OR 0.48), for the four medical conditions together (OR, 0.74) and for the three medical conditions excluding acute MI (OR, 0.79 ).

One potential explanation for the lack of a commensurate improvement among surgical residents is that duty-hour reform resulted in a relative worsening in continuity of care that offset any improvement from decreased fatigue.

Furthermore, Dr. Volpp wrote, possible reasons for the differences in findings between the studies include the markedly greater resident-to-bed ratios at VA teaching hospitals compared with non-VA teaching hospitals, potentially greater autonomy for residents at VA hospitals, differences in staffing models and clinical volume.

Potential limitations of the VA study included the lack of actual hours worked at each hospital. Also, the study may not have had sufficient power to rule out a clinically significant effect of duty- hour reform in surgical training programs, Dr. Volpp said.

In an accompanying editorial subtitled "More Work to Do," David O. Meltzer, M.D., Ph.D., and Vineet M. Arora, M.D., of the University of Chicago wrote "These results may be reassuring to those who feared that duty-hour reforms would adversely affect patients outcomes.

However, despite the suggestions of improvement in mortality in some subgroups, the overall impression remains that duty hour restrictions have had little effect on patient mortality.

Furthermore, they noted that duty-hour restriction would have little effect on acute MI patients for whom most of the interventions (early recognition and initiation of therapy) are often initiated prehospital or in the emergency department.

The Medicare and the VA study were supported primarily by a grant from U.S.Veterans Affairs Health Services Research and Development Service. Support was also received from the National Heart, Lung, and Blood Institute and from the National Science Foundation.

The editorial writers reported no financial conflicts of interest.