The Importance of Allergen Avoidance in High Risk Infants and Sensitized Patients: A Meta-analysis Study.
OBJECTIVE
At this time, there is uncertainty regarding whether allergen avoidance is the most appropriate strategy for managing or preventing allergies. The purpose of this study was to evaluate the effectiveness of allergen avoidance in the prevention of allergic symptoms in previously sensitized patients and newborns that have the potential to develop allergies.


METHODS
We performed online searches of articles published from January 1980 to December 2012 in PubMed and The Cochrane Central Register of Controlled Trials, and selected articles involving randomized controlled trials (RCTs) and allergen avoidance. The parameters used to determine allergenic potential in newborns included the risk ratio (RR) of eczema, asthma, rhinitis, wheeze, and cough. The methods employed to evaluate previously sensitized patients were the standardized mean difference (SMD) of forced expiratory volume in 1 second (FEV1) and peak expiratory flow rate (PEFR). Data quality was assessed using the Jadad scale.


RESULTS
A total of 14 RCTs were identified. Meta-analysis demonstrated that allergen avoidance for newborns did not reduce the subsequent incidence of allergic diseases (eczema, P=0.21; rhinitis, P=0.3; cough, P=0.1) but significantly reduced the incidence of asthma and wheezing in high-risk infants (asthma, P=0.03; wheeze, P=0.0004). However, previously sensitized patients who reduced their exposure to known allergens did not show improvement in their lung functions (FEV1, P=0.3; PEFR morning, P=0.53; PEFR evening, P=0.2; PEFR, P=0.29).


CONCLUSIONS
Allergen avoidance may not always be successful in preventing allergic symptoms. However, rigorous methodological studies are required to confirm this hypothesis.
Guangdong Provincial Key Laboratory of Allergy & Clinical Immunology, the State Key Laboratory of Respiratory Disease, the Second Affiliated Hospital of Guangzhou Medical University, Guangdong 510260, China.
Wu
W
Huiyan
Guangdong Provincial Key Laboratory of Allergy & Clinical Immunology, the State Key Laboratory of Respiratory Disease, the Second Affiliated Hospital of Guangzhou Medical University, Guangdong 510260, China.
Guo
G
Yuhe
Guangdong Provincial Key Laboratory of Allergy & Clinical Immunology, the State Key Laboratory of Respiratory Disease, the Second Affiliated Hospital of Guangzhou Medical University, Guangdong 510260, China.
Wang
W
Juan
Guangdong Provincial Key Laboratory of Allergy & Clinical Immunology, the State Key Laboratory of Respiratory Disease, the Second Affiliated Hospital of Guangzhou Medical University, Guangdong 510260, China.
Zhang
Z
Junyan
Guangdong Provincial Key Laboratory of Allergy & Clinical Immunology, the State Key Laboratory of Respiratory Disease, the Second Affiliated Hospital of Guangzhou Medical University, Guangdong 510260, China.
Wang
W
Shan
Respiratory Department, Southern Building, General Hospital of Chinese People's Liberation Army, Beijing 100853, China.
Zhang
Z
Xiaojun
Guangdong Provincial Key Laboratory of Allergy & Clinical Immunology, the State Key Laboratory of Respiratory Disease, the Second Affiliated Hospital of Guangzhou Medical University, Guangdong 510260, China.
Tao
T
Ailin
Meta-analysis; allergen avoidance; allergenic potential newborns; allergic diseases; previously sensitized patients