Discussion
In this study, about 90% of the 31,570 patients with anaphylaxis
treated with adrenaline were also treated with glucocorticoids. The
overall proportion of biphasic reactions was 11.2%. There were no
significant differences in rates of biphasic reactions or 7-day
all-cause mortality between those treated with and without
glucocorticoids.
Previous studies have failed to show that glucocorticoids reduce the
rate of biphasic reactions in patients with anaphylaxis of varying
severity.7,8 In the present study, which included only
patients with severe anaphylaxis, we also found no evidence that
glucocorticoids reduce the rate of biphasic reactions.
Biphasic reactions occurred on the day of the initial anaphylactic
reaction in about 90% of the patients in our study. A previous study
reported a median time between initial symptom resolution and onset of
biphasic reaction of 11 hours (range 0.2–72 hours.1The anti-allergic effects of glucocorticoids, which are thought to be
responsible for any effect on biphasic reactions, occur within 4 to 6
hours.6 Therefore, the failure of glucocorticoids to
reduce the rate of biphasic reactions may be attributable to the
difference between the time required for glucocorticoids to take effect
and the time of onset of biphasic reactions.
Long-term steroid administration is associated with adverse effects,
including infection, osteoporosis, hypertension, mood disorder, peptic
ulcer, and adrenal insufficiency. Even short-term administration may
result in avascular necrosis.13,14 Short-term steroid
use can also be associated with development of hyperglycemia within a
few hours.15 Given that this study showed no
significant association between glucocorticoid use and rate of biphasic
reaction, routine use of glucocorticoids to prevent biphasic reaction
may not be indicated, not even in patients with severe anaphylaxis
requiring intramuscular adrenaline.
This study has several limitations. First, it was a retrospective
observational study. Although we used propensity score matching to
adjust for confounding factors, our results may have been affected by
unmeasured confounding factors, including symptoms of anaphylaxis, time
from onset of anaphylaxis to treatment, use of epinephrine
autoinjectors, and the results of laboratory tests. Future research is
expected to be prospective or to use registries that include detailed
clinical data. Second, in this study, severe anaphylaxis was defined as
anaphylaxis requiring admission to hospital and treatment with
adrenaline. However, some patients without severe clinical symptoms
receive adrenaline, potentially resulting in misclassification and
underestimation of the effects of glucocorticoids.