Impact of critical illness severity on transfusion requirements

Background

Among the common problems in critically ill ICU patients is anemia, the consequences of which on mortality and morbidity are not adequately studied.

Objectives

To describe the anemia incidence and the red blood cell transfusion strategy in critically ill patients and their relationship to clinical outcome.

Patients and methods

The study period lasted from July 2003 to December 2004. The patients were enrolled within 48 hours of ICU admission. The follow-up time was 30 days, until hospital discharge or death.

Results

A total of 169 patients (116 male, 53 female, mean age 57.6 ± 2.1 years, range 15–96 years) were included in the study. The mean hemoglobin level at baseline was 11.2 ± 2.1. Overall, 63.9% (108/169) of the patients received one or more RBC units while in the ICU (mean 3.1 ± 3.8 units per patient). The mean pretransfusion Hb was 8.7 ± 1.8 g/dl and the mean time to first ICU transfusion was 2.6 ± 4.1 days. More RBC transfusions were given in the first week of the ICU stay (331 units vs 110, 61 and 36 units in the second, third and fourth week, respectively). The number of RBC units transfused during the study were positively associated with a longer ICU length of stay and increased mortality (r = 0.19, P < 0.05 and r = 0.26, P < 0.05, respectively). The baseline Hb level was significantly related to the number of RBC transfusions (r = 0.55, P < 0.001), but was not an independent predictive risk factor of length of stay or mortality (r = 0.16, P > 0.05 and r = 0.13, P > 0.05, respectively). The mean baseline APACHE II and SAPS scores were 19.6 ± 7.4 and 49.8 ± 17.4, respectively. Furthermore, both baseline APACHE II and SAPS scores were significantly higher in patients with a baseline Hb level <10 g/dl (23.2 ± 7.9 vs 18.3 ± 6.7 and 54.6 ± 18.8 vs 48.1 ± 16.5, respectively), while the APACHE II values were positively associated with a significantly increased likelihood of RBC transfusion (Pearson correlation P < 0.005).

Conclusion

In ICU patients the commonly occurring anemia appears early in their ICU course and conveys them throughout their ICU stay. More RBC transfusions are given during the first week of the ICU stay. The severity of illness seems to have a positive relation to transfusion requirements. Although a strong enough statistical correlation emerges from our study, further prospective studies with larger cohorts are required in order to definitively address the issue.