Volume of activity and occupancy rate in intensive care units. Association with mortality.
OBJECTIVE
Mortality after many procedures is lower in centers where more procedures are done. It is controversial whether this is true for intensive care units, too. We examined the relationship between the volume of activity of intensive care units (ICUs) and mortality by a measure of risk-adjusted volume of activity specific for ICUs.


METHODS
Prospective, multicenter, observational study.


METHODS
Eighty-nine ICUs in 12 European countries.


METHODS
During a 4-month study period, 12,615 patients were enrolled.


METHODS
Demographic and clinical statistics, severity at admission and a score of nursing complexity and workload were collected.


RESULTS
Total volume of activity was defined as the number of patients admitted per bed per year, high-risk volume as the number of high-risk patients admitted per bed per year (selected combining of length of stay and severity of illness). A multi-step risk-adjustment process was planned. ICU volume corresponding both to overall [odds ratio (OR) 0.966] and 3,838 high-risk (OR 0.830) patients was negatively correlated with mortality. Relative mortality decreased by 3.4 and 17.0% for every five extra patients treated per bed per year in overall volume and high-risk volume, respectively. A direct relationship was found between mortality and the ICU occupancy rate (OR 1.324 and 1.351, respectively).


CONCLUSIONS
Intensive care patients, whatever their level of risk, are best treated where more high-risk patients are treated. Moreover, the higher the ICU occupancy rate, the higher is the mortality.
Lapichino
Gaetano
G
Istituto di Anestesiologia e Rianimazione, Università di Milano, Azienda Ospedaliera-Polo Universitario San Paolo, Via A Di Rudinì 8, 20142 , Milan, Italy. g.iapichino@unimi.it.
Gattinoni
Luciano
L
IRCCS Ospedale Maggiore, Milan, Italy.
Radrizzani
Danilo
D
Servizio Anestesia e Rianimazione, Ospedale Civile, Legnano, Italy.
Simini
Bruno
B
GiViTi Coordination Centre, Istituto di Ricerche Farmacologiche "Mario Negri, Ranica, Bergamo, Italy.
Bertolini
Guido
G
GiViTi Coordination Centre, Istituto di Ricerche Farmacologiche "Mario Negri, Ranica, Bergamo, Italy.
Ferla
Luca
L
Istituto di Anestesiologia e Rianimazione, Università di Milano, Azienda Ospedaliera-Polo Universitario San Paolo, Via A Di Rudinì 8, 20142 , Milan, Italy.
Mistraletti
Giovanni
G
Istituto di Anestesiologia e Rianimazione, Università di Milano, Azienda Ospedaliera-Polo Universitario San Paolo, Via A Di Rudinì 8, 20142 , Milan, Italy.
Porta
Francesca
F
Istituto di Anestesiologia e Rianimazione, Università di Milano, Azienda Ospedaliera-Polo Universitario San Paolo, Via A Di Rudinì 8, 20142 , Milan, Italy.
Miranda
Dinis R
DR
Foundation for Research on Intensive Care in Europe, University Hospital, Groningen, The Netherlands.
D016638:Critical Illness; D005060:Europe; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units / Q000592:standards / Q000706:statistics & numerical data*; D016015:Logistic Models; D011446:Prospective Studies; D011785:Quality Assurance, Health Care; D016526:Workload