Evidence
This page contains a snapshot of featured content which highlights evidence addressing key clinical questions including areas of uncertainty. Please see the main topic reference list for details of all sources underpinning this topic.
BMJ Best Practice evidence tables
Evidence tables provide easily navigated layers of evidence in the context of specific clinical questions, using GRADE and a BMJ Best Practice Effectiveness rating. Follow the links at the bottom of the table, which go to the related evidence score in the main topic text, providing additional context for the clinical question. Find out more about our evidence tables.
This table is a summary of the analysis reported in a guideline (underpinned by a systematic review) that focuses on the above important clinical question.
Confidence in the evidence is very low or low where GRADE has been performed and the intervention may be more effective/beneficial than the comparison for key outcomes. However, this is uncertain and new evidence could change this in the future.
Population: Patients with suspected anaphylaxis
Intervention: One (earlier) timing of mast cell tryptase testing ᵃ
Comparison: Any other (later) timing ᵃ
| Outcome | Effectiveness (BMJ rating)? | Confidence in evidence (GRADE)? |
|---|---|---|
Timing of peak mast cell tryptase | See note ᵇ | Very Low |
End-point of elevated mast cell tryptase | See note ᶜ | Very Low |
Recommendations as stated in the source guideline After a suspected anaphylactic reaction in adults or young people aged 16 years or older, take timed blood samples for mast cell tryptase testing as follows: A sample as soon as possible after emergency treatment has started A second sample ideally within 1-2 hours (but no later than 4 hours) from the onset of symptoms.
Note The guideline committee stated that the timing of the first blood sample should be as soon as possible since the evidence suggests a median time of 30 minutes for the peak of mast cell tryptase, and that the peak was reached within two hours in all but two patients. ᵃ The guideline committee did not identify any randomised controlled trials (RCTs) so they included observational studies. ᵇ The guideline committee noted that the timing of peak levels ranged from 1 minute to 6 hours (median 30 minutes, 7 studies, N=178) and that levels were reported as median 24 units per litre (range 4.09–66.2). ᶜ The guideline committee also noted the half-life of tryptase ranged from 30 minutes to 300 minutes (median 90 minutes, 6 studies, N=147) with levels returning to normal by 24 hours after onset of symptoms. Normal levels were reported at six hours in one study.
This evidence table is related to the following section/s:
Cochrane Clinical Answers
Cochrane Clinical Answers (CCAs) provide a readable, digestible, clinically focused entry point to rigorous research from Cochrane systematic reviews. They are designed to be actionable and to inform decision making at the point of care and have been added to relevant sections of the main Best Practice text.
- Is there randomized controlled trial evidence to support the use of venom immunotherapy to prevent allergic reactions to insect stings?
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