22
3.15 Triggers of Angioedema Episodes
Most attacks are spontaneous, and it is impossible
to identify a contributing factor.
5,10,11,41
Nonetheless,
specific triggering events have been linked to attacks of
HAE, although these vary from patient to patient
(Table 6).
5,10,11,22,30
Even within the same patient, a potential
trigger may result in an attack on one occasion and not
another.
5,10
3.14 Frequency of HAE Attacks
As indicated previously, the number of attacks a patient
experiences varies from year to year and from one individual
to another – even if they have the same mutation. A small
number of patients identified as carrying the HAE genotype
are spared HAE attacks altogether.
5,30
However, about half of patients suffer 1 or more attacks a
month. In extreme cases, HAE attacks can occur once or
twice a week. The frequency of attacks does not correlate
with the level of residual activity of endogenous C1-INH.
30
Even life-threatening laryngeal attacks can occur frequently
in some patients. Bork et al reported that some individuals
with upper airway edema experienced up to 30, 50, or
even 200 laryngeal episodes during a follow-up period of
1 to 29 years.
38
In the PREHAEAT registry, the frequency of attacks of
angioedema during the past year differed considerably
among patients (Figure 10). Only 19% of patients had
been symptom-free.
23
Frequency of HAE Attacks in 1,168 Patients
Number of Patients
Number of Attacks During 1 Year
none
6-11
1-5
12-24 >24 unknown
500
450
400
350
300
250
200
150
100
50
0
Figure 10 – Frequency of Angioedema Attacks
in 1,168 Patients During 1 Year
Adapted from 23.
Agostoni
et al. (1992)
30
Winnewisser
et al. (1997)
41
Farkas (2010)
32
Pediatric
Patients
Adult
Patients
Number of Patients
226
58
49
NA
Trigger (% of Patients)
a
Trauma
53
57
53
54
(Mental) Stress
26
41
37
57
Insect bites/stings
–
26
–
–
Physical exertion
–
–
–
60
Foods
–
29
–
–
Menstruation
15
–
27
27
Airway infection
–
–
37
37
Pregnancy
–
–
–
39
NA=Data not available.
a
In the majority of attacks, a trigger could not be identified.
In some cases, more than 1 factor was identified.
Table 6 – Factors That Precipitated Attacks of Angio-
edema in Patients With Hereditary Angioedema
