Epidemiology of Massive Transfusion: A Binational Study From Sweden and Denmark.

Objective: There is an increasing focus on massive transfusion, but there is a paucity of comprehensive descriptions of the massively transfused patients and their outcomes. The objective of this study is to describe the incidence rate of massive transfusion, patient characteristics, and the mortality of massively transfused patients.
Design: Descriptive cohort study.
Setting: Nationwide study with data from Sweden and Denmark.
Patients: The study was based on the Scandinavian Donations and Transfusions database, including all patients receiving 10 or more red cell concentrate transfusions in Sweden from 1987 and in Denmark from 1996. A total of 92,057 patients were included. Patients were followed until the end of 2012.
Measurements and Main Results: Descriptive statistics were used to characterize the patients and indications. Post transfusion mortality was expressed as crude 30-day mortality and as long-term mortality using the Kaplan-Meier method and using standardized mortality ratios. The incidence of massive transfusion was higher in Denmark (4.5 per 10,000) than in Sweden (2.5 per 10,000). The most common indication for massive transfusion was major surgery (61.2%) followed by trauma (15.4%). Massive transfusion due to obstetrical bleeding constituted only 1.8%. The overall 5-year mortality was very high (54.6%), however with large differences between indication groups, ranging from 91.1% among those transfused for a malignant disease without surgery to 1.7% among patients transfused for obstetrical bleeding. The early standardized mortality ratios were high and decreased thereafter, but remained elevated throughout the time period.
Conclusions: This large-scale study based on nationwide data from Sweden and Denmark describes the complete range of massive transfusion. We report a nonnegligible incidence and both a high absolute mortality and high standardized mortality ratio. The general pattern was similar for Sweden and Denmark, and we believe that similar patterns may be found in other high-resource countries. The study provides a relevant background for clinicians and researchers for designing future studies in this field.