Table 1 Structured question

Population

• adult patients with traumatic brain injury

Intervention

• red blood cell transfusion

Comparator

• no transfusion

Primary outcome

• frequency of red blood cell transfusion

Secondary outcomes

• transfusion thresholds

• number of red blood cell units transfused

• determinants of red blood cell transfusion

• mortality

• frequency of withdrawal of life-sustaining therapy

• frequency of unfavourable neurological outcome

• ICU and hospital length of stay

• all other reported clinical outcomes

Study design

• cohort studies (both prospective and retrospective) and randomized controlled trials