The number of resident physicians and the mortality rate in a medical intensive care unit

Background/Aims: The treatment outcome of patients hospitalized in intensive care units (ICUs) can be influenced by physician factors, including both intensivists and resident physicians. We evaluated the association between the number of residents who are exclusively responsible for the ICU and the mortality rate in a medical ICU. Methods: The data obtained from an open medical ICU in a teaching hospital from Jan. 2005 to Dec. 2009 were analyzed retrospectively. We evaluated the associations between the ICU mortality rate and both the number of resident physicians and the number of patient-days per resident physician using multivariate Poisson regression analysis adjusted for year and month. Results: The months with fewer than two residents tended to have a higher ICU mortality rate, although this difference was not significant in the univariate analyses. Multivariate Poisson regression analysis showed that months with fewer than two residents had a significantly higher ICU mortality rate compared with months with two residents (incidence risk ratio (IRR) 1.59, 95% confidence interval (CI) 1.05-2.41; p=0.029). The number of ICU patient-days per resident physician was not associated with the ICU mortality rate (IRR; 1.00, 95% CI, 0.99-1.01; p=0.649). Conclusions: The presence of fewer than two residents exclusively responsible for the medical ICU was an independent risk factor of a higher ICU mortality rate. However, no association was found between the number of ICU patient-days per resident physician and the ICU mortality rate. (Korean J Med 79:155-162, 2010)