PURPOSE: Hebert et al demonstrated a decrease in the mean number of packed red blood cell (pRBC) transfusions when using a restrictive transfusion strategy (Hb<7g/dL) vs a liberal one (Hb<10g/dL) without compromising outcomes. (1) However, current practice in US intensive care units (ICUs) is to transfuse at Hb ∼8.5 g/dL. (2) Using data from the CRIT study, we modeled the effects of lowering the Hb trigger from current practice to a restrictive approach on transfusion risk and pRBC use.
METHODS: CRIT was a prospective cohort study of US ICU patients. For these analyses, we defined ICUs where the mean pretransfusion Hb was ≤7.5g/dL as restrictive, and those with mean pretransfusion Hb 8.3-8.7g/dL as nonrestrictive. After calculating the unadjusted transfusion difference between the restrictive and nonrestrictive groups, the covariate-adjusted reduction in the risk and amount of pRBC transfusions associated with lowering the trigger was estimated. Age, gender, baseline APACHE II and SOFA scores, specific admitting diagnosis (ie, respiratory failure, postoperative, pneumonia, trauma, or COPD), and baseline Hb were controlled for.
RESULTS: Of the total 284 ICUs, 8 (3%) followed a restrictive strategy (ICU mean pretransfusion Hb=7.2±1.6 g/dL) and 65 (23%) a nonrestrictive one (ICU mean pretransfusion Hb=8.5±1.3 g/dL). Patients in the two groups (n=157 restrictive, n=1656 nonrestrictive) were similar with respect to their age, gender, baseline Hb, and APACHE II and SOFA scores. Unadjusted rate of transfusion was 34.4% with the overall mean 1.17 ± 2.30 units/patient in the restrictive group, and 46.8% with 2.19 ± 4.15 units/patient in the nonrestrictive group. After controlling for covariates, the difference in both, transfusion rates (adjusted risk difference 5.1%) and transfusion amount (0.7 u pRBC) decreased.
CONCLUSION: Further lowering hemoglobin triggers is likely to result in less reduction in the risk and amount of exposure to pRBCs than that observed by Hebert and colleagues.
CLINICAL IMPLICATIONS: Current transfusion practices as well as complementary interventions need to be considered in order to develop a comprehensive strategy to reduce blood exposure and utilization in the ICU. 1.Hebertetal.NEnglJMed1999;340:409-417. 2.Corwinetal.CritCareMed.2004;32:39-52.
DISCLOSURE: Andrew Schorr, Grant monies (from industry related sources) This study was supported by Ortho Biotech Clinical Affairs, LLC; Consultant fee, speaker bureau, advisory committee, etc. Andrew F. Shorr is an consultant for Ortho Biotech Clinical Affairs, LLC.