TRICC Trial

What was the research question?

• Does restrictive blood transfusion improve mortality compared to liberal blood transfusion strategy in patients who were admitted to the ICU?

How did they do it?

• Randomized, non-blinded, control trial in 25 ICUs in Canada.

• 6541 adult patients were assessed of whom 838 randomized to receive restrictive strategy targeting Hb level of 7-9 g/dl, or liberal strategy with Hg target of 10-12 g/dl.

What did they find?

• Primary outcome of 30-day mortality was similar in restrictive strategy compared to liberal strategy (18.7% vs. 23.3%; P=0.11). However, in sub-group analysis, mortality was significantly lower in less acutely ill patients with APACHE II score ≤ 20 (8.7% vs. 16.1%, p=0.03), and in patients younger than 55 years (5.7% vs. 13%, P=0.02). In patients with cardiac disease, the morality rate was similar (20.5% vs. 22.9%, p=0.69).

• Cardiac events (MI, pulmonary oedema, angina, cardiac arrest) were less common in restrictive strategy compared to liberal strategy (13.3% vs. 21%; P<0.01).

• Secondary outcome of hospital mortality was lower in the restrictive group compared to the liberal group (22.2% vs 28.1%; P=0.05).

What are the limitations of the study?

• Possible selection bias as only 13% patients were included in the trial.

• Subgroup APACHE score was changed from <15 to <20 post hoc, likely to get the significant results.

• Possibility of type II error as the sample was only 838 compared to 1620 needed for the power of the study.

• No subgroup analysis for patients with traumatic brain.

What does it mean?

• A restrictive strategy of red-cell transfusion is at least as effective as and possibly superior to a liberal transfusion strategy in critically ill patients, with the possible exception of patients with acute myocardial infarction and unstable angina.

• The transfusion threshold in critically ill patients is changed based on this study from <9 g/dL to <7 g/dL except in patients with evidence of active cardiac ischemia.