restrictive blood transfusion strategies 2014.pdf

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The American Journal of Medicine, Vol 127, No 2, February 2014


Potentially relevant studies
identified and screened for
retrieval (n = 4500)

Studies excluded:
Not trials of transfusion triggers (n = 4369)
Studies used for systematic review

Trials of transfusion triggers
In anemia (n = 32)

Trials excluded:
Not randomized (n = 2)

Randomized trials of transfusion
triggers in anemia (n = 30)

Trials excluded from primary analysis:
Used less-restrictive trigger (n = 19)
(16 trials used in secondary analysis)
Did not provide clear trigger (n = 4)
Duplicate data from other trials (n = 4)

Primary analysis:
Randomized controlled trials of a
restrictive transfusion strategy using
a hemoglobin trigger of < 7 g/dL,
compared with a more liberal
strategy (n = 3)
Figure 1

Flow chart of trials search for meta-analysis.

Primary Meta-analysis
Search Results. The search identified approximately 4500
studies, of which 32 were potentially relevant trials evaluating transfusion triggers (Figure 1). Of these, 3 trials met
inclusion criteria for the primary analysis.12,23,28 One
study provided unpublished information.23 Studies were
excluded for the following reasons: Two were not randomized, 19 used a less-restrictive hemoglobin transfusion
trigger of >7 g/dL, 4 did not provide a clear transfusion
trigger, and 4 provided duplicate data on participants
included in another trial. Of the 19 trials evaluating a

less-restrictive strategy, 16 provided data on clinical outcomes and were evaluated separately.6-11,21,29-37
Trial Characteristics. The primary analysis included 3
trials, with a total of 2364 participants followed for mean
trial duration of 45 days. The characteristics of the included
trials, including their risk of bias, are shown in Appendix
Figure 1 (online). The mean study size was 788 participants (range, 637-889), with a mean participant age of 45.7
years (standard deviation, 16 years). Transfusion strategies
were evaluated in the setting of adult critical care,12 pediatric critical care,28 and acute upper gastrointestinal