The shortest observation period after successfully treated anaphylaxis
Research type
Research Study
Full title
What is the shortest safe period of observation for emergency department patients who have received adrenaline for the treatment of anaphylaxis and whose symptoms have resolved?
IRAS ID
246346
Contact name
Graham Johnson
Contact email
Sponsor organisation
University Hospitals Derby and Burton NHS Foundation Trust
Duration of Study in the UK
1 years, 5 months, 31 days
Research summary
Anaphylaxis is a life-threatening, immune-mediated compromise of a patient's airway, breathing or circulatory systems in response to an external allergen. Since 1992 hospital admissions with anaphylaxis in the UK have increased from 1.0 to 7.0 per 100,000 population per year. Despite this increase in admission rate the mortality has remained essentially unchanged.
The main driver for this increase in admissions is concern regarding biphasic reactions. A biphasic reaction consists of "recurrent or new signs or symptoms occurring after an initial allergy-related symptom, which satisfy the definition of anaphylaxis, without any obvious further exposure to an offending allergen." The incidence of biphasic reactions is an issue of some debate, with estimates ranging from 1 - 20% of all anaphylactic reactions. Optimal management cannot be determined from the existing literature base due to limitations with regard to small numbers of patients experiencing biphasic reactions.
The primary aim of this study is to identify the shortest safe period of hospital observation for emergency department (ED) patients who have been treated with adrenaline for an anaphylactic reaction and who are now asymptomatic.
The study will consist of a retrospective case-note review. Records will be identified through a search of the electronic ED record. Case notes will be included if the patient met the diagnostic criteria for anaphylaxis.
The primary objective is to establish the incidence and timing of biphasic reactions in those not requiring ICU/HDU admission.
The secondary objective is to identify factors predictive of biphasic reactions.
All notes reviewed will be from patients treated in the Royal Derby Hospital Emergency Department.
This study was funded by an internal grant award.
Summary of Results
This study aimed to identify the shortest safe period of hospital observation for patients who present to the Emergency Department who have required adrenaline for the treatment of an anaphylactic reaction whose symptoms have improved following treatment. The 2011 NICE Guidance suggested 6-12 hours, however there may be patients who are clinically well who can be safely discharged more quickly.
This study involved collecting all the notes of patients who had been treated in the emergency department of the Royal Derby Hospital in the last 10 years.
342 adult and paediatric patients were included for analysis.In those patients who had clinically improved within the emergency department, such that their heart rate, blood pressure and other parameters had returned to normal, 0.6% of patients had a biphasic reaction which required them to return for further treatment. These reactions were occurred several days after the initial reaction without further re-exposure to the allergen.
REC name
London - Stanmore Research Ethics Committee
REC reference
18/LO/2213
Date of REC Opinion
19 Mar 2019
REC opinion
Further Information Favourable Opinion