Variation in red cell transfusion practice in the intensive care unit: a multicentre cohort study

Objectives: To determine the degree of interinstitutional transfusion pract ice variation and reasons why red cells are administered in critically ill patients. Study design: Multicentre cohort study combined with a cross-sectional surv ey of physicians requesting red cell transfusions for patients in the cohor t. Study population: The cohort included 5298 consecutive patients admitted to six tertiary level intensive care units in addition to administering a sur vey to 223 physicians requesting red cell transfusions in these units. Measurements: Haemoglobin concentrations were collected, along with the num ber and reasons for red cell transfusions plus demographic, diagnostic, dis ease severity (APACHE II score), intensive care unit (ICU) mortality and le ngths of stay in the ICU. Results: Twenty five per cent of the critically ill patients in the cohort study received red cell transfusions. The overall number of transfusions pe r patient-day in the ICU averaged 0.95 +/- 1.39 and ranged from 0.82 +/- 1. 69 to 1.08 +/- 1.27 between institutions (P< 0.001). Independent predictors of transfusion thresholds (pre-transfusion haemoglobin concentrations) inc luded patient age, admission APACHE II score and the institution (P< 0.0001 ). A very significant institution effect (P < 0.0001) persisted even after multivariate adjustments for age, APACHE II score and within four diagnosti c categories (cardiovascular disease, respiratory failure, major surgery an d trauma) (P< 0.0001). The evaluation of transfusion practice using the bed side survey documented that 35% (202 of 576) of pre-transfusion haemoglobin concentrations were in the range of 95-105 g/l and 80% of the orders were for two packed cell units. The most frequent reasons for administering red cells were acute bleeding (35%) and the augmentation of O-2 delivery (25%). Conclusions: There is significant institutional variation in critical care transfusion practice, many intensivists adhering to a 100 g/l threshold, an d opting to administer multiple units despite published guidelines to the c ontrary. There is a need for prospective studies to define optimal practice in the critically ill.