Anemia prevalence and incidence and red blood cell transfusion practices in aneurysmal subarachnoid hemorrhage: results of a multicenter cohort study

Abstract

Background: Whether a restrictive strategy for red blood cell (RBC) transfusion is applied to patients with aneurysmal subarachnoid hemorrhage (aSAH) is unclear. To inform the design and conduct of a future clinical trial, we sought to describe transfusion practices, hemoglobin (Hb) triggers, and predictors of RBC transfusion in patients with aSAH.

Methods: This is a retrospective cohort study of all consecutively admitted adult patients with aSAH at four tertiary care centers from January 1, 2012, to December 31, 2013. Patients were identified from hospital administrative discharge records and existing local aSAH databases. Data collection by trained abstractors included demographic data, aSAH characteristics, Hb and transfusion data, other major aSAH cointerventions, and outcomes using a pretested case report form with standardized procedures. Descriptive statistics were used to summarize data, and regression models were used to identify associations between anemia, transfusion, and other relevant predictors and outcome.

Results: A total of 527 patients met inclusion eligibility. Mean (±SD) age was 57 ± 13 years, and 357 patients (67.7%) were female. The median modified Fisher grade was 4 (IQR 3-4). Mean nadir Hb was 98 ± 20 g/L and occurred on median admission day 4 (IQR 2-11). RBC transfusion occurred in 100 patients (19.0%). Transfusion rates varied across centers (12.1-27.4%, p = 0.02). Patients received a median of 1 RBC unit (IQR 1-2) per transfusion episode and a median total of 2 units (IQR 1-4). Median pretransfusion Hb for first transfusion was 79 g/L (IQR 74-93) and did not vary substantially across centers (78-82 g/L, p = 0.37). Of patients with nadir Hb < 80 g/L, 66.3% received a transfusion compared with 2.0% with Hb nadir ≥ 100 g/L (p < 0.0001). Predictors of transfusion were history of oral anticoagulant use, anterior circulation aneurysm, neurosurgical clipping, and lower Hb. Controlling for numerous potential confounders, transfusion was not independently associated with poor outcome.

Conclusions: We observed that moderate anemia remains very common early in admission following SAH. Only one-fifth of patients with SAH received RBC transfusions, mostly in cases of significant anemia (Hb < 80 g/L), and this did not appear to be associated with outcome.

Keywords: Anemia; Cerebral aneurysm; Cohort study; Red blood cell transfusion; Subarachnoid hemorrhage.

Fig. 1

Red blood cell transfusion rates across hemoglobin thresholds. Proportion of patients transfused according to hemoglobin threshold. Error bar depicts proportion 95% CI

Fig. 2

Red blood cell transfusion threshold site variation. Whisker box plot of pretransfusion hemoglobin according to site. The center line in the box represents the median, and the outside lines of the box represent the first and third quartiles. The lines extending from the boxes demonstrate the minimum and maximum values