[Seasonal influence on the diagnosis of food allergy in children less than 3 years of age].
OBJECTIVE
To investigate the seasonal influence on the diagnosis of food allergy in children under 3 years of age.


METHODS
The data of epidemiological studies about food allergy of children under 3 years of age attending routine well-baby checks at the Department of Primary Child Care, Children's Hospital of Chongqing Medical University in the winter and summer, 2009, including questionnaires, results of skin prick test (SPT), food elimination and oral food challenge (OFC) were analyzed. All the data were analyzed by SPSS 17.0.


RESULTS
The age and sex distribution, and both the rates of the drop-out in two studies were similar. Ninety infants were positive for SPT, 40 infants were positive for OFC, and 31 infants dropped out in winter; while 65 infants were positive for SPT, 25 positive for OFC, and 31 dropped out in summer. The percentage of positive SPT in the children performed in winter was higher than that in summer (14.9%, 90/603 vs 10.7%, 65/607) (P = 0.028). Skin prick test accuracy was similar when the studies were performed in winter and in summer [sensitivity 0.85 and 0.84, positive predictive value (PPV) 0.54 and 0.47, negative predictive value (NPV) 0.99 and 0.99]. The prevalence of food allergy in the children studied in winter was higher than that in summer (7.0% vs 4.3%), but the difference was not significant. After correcting the prevalence for dropout children, the prevalence of food allergy (FA) investigated in winter was significantly higher than that in summer (9.3% vs 5.9%). The results of circular distribution analysis showed the date of birth corresponding to estimated value of peak point of SPT in winter were not consistent with it in summer, so was OFC. Either the results of skin prick test or oral food challenge in two studies were not correlated with the seasons of birth.


CONCLUSIONS
Our data showed that the rates of positive SPT and the prevalence of food allergy were correlated with the seasons, but the seasons of birth did not influence the results of skin prick test or oral food challenge in children, while the real age of children were related to them.
Department of Primary Child Care, Children's Hospital, Chongqing Medical University, Chongqing 400014, China.
Li-qing
LQ
Zhou
Jing
J
Chen
Yan
Y
Hu
Email: haiqili2010@hotmail.com.
Hai-qi
HQ
Li
D000367:Age Factors; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D005260:Female; D005512:Food Hypersensitivity / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011237:Predictive Value of Tests; D015995:Prevalence; D012621:Seasons; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D012882:Skin Tests / Q000379:methods; D011795:Surveys and Questionnaires