INTRODUCTION
Cow’s
milk allergy (CMA) is a significant public health issue worldwide. It is
defined as a reproducible adverse reaction to one or more cow’s milk
proteins, typically casein or serum beta-lactoglobulin, and is the most
common allergen in early life[1]. Epidemiological
data indicate that the prevalence of CMA in infants and young children
in developed countries ranges from 0.5% to 3%, however, the prevalence
of the condition in adults is extremely rare, at around 0.5%, with some
regional variations[2]. Milk allergies can be
classified into three types based on the immune mechanisms:
Ige-mediated, non-Ige-mediated, and a combination of both. This can
result in a range of symptoms, including urticaria, angioedema,
gastrointestinal symptoms (such as abdominal pain, vomiting, and
diarrhea, respiratory symptoms (such as dyspnea, coughing, and
wheezing), and cardiovascular symptoms (such as dizziness, confusion,
and hypotension). Patients with CMA often experience a severely impacted
quality of life, leading to malnutrition, feeding difficulties, as well
as the risk of accidental exposure resulting in fatal anaphylactic
reactions[3-5].
An accurate diagnosis of milk allergy is critical to managing and
preventing severe allergic reactions and preventing unnecessary dietary
restrictions[6]. The diagnosis of cow’s milk
allergy is confirmed by allergy history, skin prick test (SPT), specific
immunoglobulin E (sIgE), atopy patch test
(APT), and oral food challenges
(OFC), however, SPT and sIgE have low sensitivity and
specificity[7], APT is rarely used in the clinic.
Although the double-blind oral food challenges (DBOFC) is the gold
standard for diagnosis, its limitations have become more apparent over
time; this technique is difficult to perform, time-consuming, costly,
and may cause severe allergic reactions[8]. In
addition, OFC results do not predict the severity of subsequent
reactions[9], and there is no direct correlation
between the triggering thresholds experienced by patients during OFC and
the severity of reactions following accidental
exposure[10].
In light of the limitations of traditional methods for diagnosing milk
allergy, Component Resolved
Diagnostics (CRD) has emerged as a valuable tool in allergology research
for measuring specific IgE antibodies over the past
decade[11]. This method involves the IgE using a
small amount of serum from capillaries, allowing for the identification
of the main sensitizing components of milk[12].
The three most significant allergens in milk are casein (Bos d 8),
b-lactoglobulin (Bos d 5), and a-lactoglobulin (Bos d 4), with
sensitization to other minor proteins, such as bovine serum albumin (Bos
d 6), also being reported[13], CRD can distinguish
between sensitization due to co-sensitization and cross-reactivity,
helping to rule out allergy[12-14]. As CRD
technology improves, it can be used not only to assess the risk,
severity, persistence, and prognosis of clinical reactions[15], but also to identify those patients who
would benefit from it[16, 17], and provide more
effective and safer allergy immunotherapy regimens for
patients[18]. However, the diagnostic accuracy of
the identified components has varied in different studies, so the
diagnostic value and clinical application of CRD for milk allergy remain
unclear.
Although our previous systematic review evaluated the diagnostic
accuracy of various food allergy tests, there have been limited studies
on CRD. To our knowledge, only a few studies have addressed the
diagnostic test accuracy (DTA) review for CRD, with a primary focus on
peanut, hazelnut, and nut allergy
diagnosis[19-21]. There is only one systematic
review that evaluates the diagnostic accuracy of CRD for milk allergy,
but it only includes two studies[22]. With the
increasing number of studies on CRD in milk allergy, there is a need for
a more comprehensive review of the evidence regarding the diagnostic
accuracy of CRD in milk allergy, which would help to reduce
overdiagnosis and provide evidence for the necessity of OFC during the
final diagnosis. Therefore, we conducted a systematic review to
determine the accuracy of CRDs for the diagnosis of milk allergy.