Surprisingly, and contrary to previous findings, new research indicates that critically ill patients who are managed by a critical care physician are more likely to die than those managed by other doctors.
While some of this difference reflects the fact that patients treated by critical care physicians are generally sicker, even after adjusting for this, mortality was still higher, according to the report in the Annals of Internal Medicine for June 3.
As an accompanying editorial emphasizes, however, the mechanisms by which intensivist care might increase mortality are unclear.
"Our study, which to our knowledge is based on the largest cohort ever analyzed to examine the relationship of critical care management to survival of critically ill patients, found some unexpected results," Dr. Mitchell M. Levy, from Rhode Island Hospital in Providence, and colleagues note.
Further studies, the team adds, are needed to determine if the findings might have been the result of some unrecognized remaining confounder of illness severity.
Analyzing data from 101,832 patients in 123 ICUs in the US, the researchers found that in addition to being sicker than patients treated by non-critical care physicians, those treated by critical care doctors received more procedures.
As noted, hospital mortality was higher for patients managed by critical care physicians. Adjustment for illness severity (Simplified Acute Physiology Score) and the probability of selective referral to a critical care physician reduced, but did not eliminate, the mortality difference.
Specifically, the team reports, "Among patients who received CCM (critical care management) in ICUs that managed 5% to 95% of patients, the standardized mortality ratio was 1.09 for patients who received CCM for the entire stay compared with 0.91 for patients who did not receive CCM."
The researchers put forth some potential explanations for their findings, including the possibility that intensivists are more likely than other physicians to abandon standardized protocols and follow their own clinical judgment and the possibility that because they are more comfortable performing procedures, they do more of them, thereby increasing the risk of complications.
In a related editorial, Dr. Gordon D. Rubenfeld, from the University of Toronto, and Dr. Derek C. Angus, from the University of Pittsburgh, comment that "although Levy and colleagues speculate about mechanisms by which intensivists might increase mortality, they do not provide evidence to support a proposed mechanism."
They add that "until someone replicates Levy and colleagues' results in another cohort and provides evidence for a mechanism by which intensivist-staffed ICUs increase mortality, their study will remain one observation against many."
Ann Intern Med 2008;148:801-809,877-880.
Reviewed by Dr. Ramaz Mitaishvili
