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Mortality of life support patients does not differ by hospital volume


The mortality rates of adult medical and surgical patients who receive life support in Ontario are not significantly different between hospitals that treat a large number of life support patients and those that treat very few, a new study from the Institute for Clinical Evaluative Sciences (ICES) shows.

“The care of trauma, neonatal and pediatric intensive care unit (ICU) patients in Ontario is already regionalized to hospitals that care for higher volumes of these patients. It has been suggested that adult intensive care services also be regionalized to high volume hospitals,” said study lead author and ICES research fellow Dr. Dale Needham. “However, previous research has demonstrated conflicting results regarding the benefits of higher volume hospitals for adult intensive care patients.”

In order to evaluate if a volume-outcome relationship exists, investigators tracked more than 20,000 adult medical and surgical patients who received mechanical ventilation for at least three days in an Ontario ICU between 1998 and 2000. Patients were defined as surgical if ventilation was initiated on the same or subsequent day after surgery. Otherwise, patients were defined as medical. Within these groups, they examined the odds of death within 30 days of initiation of mechanical ventilation in relation to the hospital’s volume of ventilated patients. It was found that hospital volume had no effect on 30-day mortality for surgical patients.

The investigators also found that most low volume hospitals (those that treated less than 100 ventilated patients per year) are already transferring many of their medical patients requiring ventilation for at least three days to higher volume hospitals (those that treated more than 700 ventilated patients per year). Consequently, for most ventilated medical patients there is also no effect of hospital volume on 30-day mortality. The overall mortality rate for ventilated medical patients is 40%.

However, at low volume hospitals that did not routinely transfer ventilated medical patients, there may be an increase in mortality compared to the highest volume hospitals.

“These results show that only a minority of medical patients receiving mechanical ventilation at the lowest volume hospitals in Ontario may benefit from an increased rate of transfer to high volume facilities,” said Dr. Needham.

“Therefore, increasing transfers of these medical patients who require mechanical ventilation from very low volume hospitals to larger facilities to improve their mortality could be done fairly easily within the current healthcare system in Ontario.

“Moreover, having some surgical patients requiring mechanical ventilation (for whom there was no difference in mortality at low and high volume hospitals) remain at low volume hospitals may be beneficial in maintaining physician and staff skills and equipment at these hospitals. Maintenance of these skills and equipment are important in order to be prepared for stabilizing critically ill patients before transfer and for continued access to surgical care in these communities.”

The study, “Hospital volume and mortality for mechanical ventilation of medical and surgical patients: a population-based analysis using administrative data”, is in the September 2006 issue of the journal Critical Care Medicine.

Author affiliations: ICES (Drs. Needham, Bronskill, Laupacis, and Stukel, and Ms. Rothwell); Division of Pulmonary and Critical Care Medicine, Johns Hopkins University (Dr. Needham); Departments of Health Policy, Management and Evaluation (Drs. Bronskill, Laupacis and Stukel), Critical Care Medicine (Dr. Sibbald), Medicine (Drs. Sibbald and Laupacis), University of Toronto; Departments of Anesthesiology/Critical Care Medicine, Surgery, and Health Policy and Management (Dr. Pronovost), Johns Hopkins University.

ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.


Read the Journal Article