Anemia, transfusions and hospital outcomes among critically ill patients on prolonged acute mechanical ventilation: a retrospective cohort study

Marya D Zilberberg , Lee S Stern , Daniel P Wiederkehr , John J Doyle and Andrew F Shorr

Critical Care 2008, 12:R60doi:10.1186/cc6885


Published:	28 April 2008

Abstract (provisional)

Introduction

Patients requiring prolonged acute mechanical ventilation (PAMV) represent 1/3 of all MV patients, but utilize 2/3 of hospital resources devoted to MV. Measures are needed to optimize efficiency of care in this population. Both duration of ICU and MV are associated with anemia and increased rates of packed red blood cell (pRBC) transfusions. We hypothesized that transfusions among patients on PAMV are common and associated with worsened clinical and economic outcomes.

Methods

A retrospective analysis of a large integrated claims database covering a 5-year period (January 2000 to December 2005) was conducted on adult patients on PAMV (MV for [greater than or equal to]96 hours). The incidence of pRBC transfusions was examined as the main exposure variable, and hospital mortality served as the primary, with hospital LOS and costs as secondary outcomes.

Results

The study cohort included 4,344 hospitalized patients on PAMV (55% male, mean age: 61.5 +/- 16.4 years). Although Hb level upon admission was >10g/dL in 75% of patients, 67% (n = 2,912) received at least one transfusion, with a mean of 9.1 +/- 12.0 units of pRBCs transfused per patient over the course of the hospitalization. In regression models adjusting for confounders, exposure to pRBCs was associated with a 21% increase in the risk of hospital death (95% CI 1.00 to 1.48), and a marginal increase in LOS 6.3 days (95% CI 5.1 to 7.6) and costs $48,972 (95% CI $45,581 to $52,478).

Conclusions

Patients on PAMV have a high likelihood of being transfused with multiple units of blood at relatively high Hb levels. Transfusions independently contribute to an increased risk of hospital death, LOS and costs. Reducing PAMV patients' exposure to blood may represent an attractive target for efforts to improve quality and efficiency of healthcare delivery to this population.