Risks on asthma among city children in China: a nationwide case-control study / 中华流行病学杂志

ABSTRACT

Objective A case control study was designed to explore the risk factors of asthma for city children residing for more than half a year,in China.Methods All physician-diagnosed asthma children enrolled in the 3rd nationwide survey (2010) in 43 typical cities of China were selected as the cases,and non-asthmatic children in the same survey were selected as control subjects if they wcre matched with the cases in age and sex.A revised questionnaire on the basis of ISAAC Phase Three Environmental Questionnaire was designed to investigate the risks of asthma among city children aged 0-14 years in China.Chi square analysis and generalized linear mixed models were performed to check the exposure difference between the cases and the controls.Results 43 out of the 44 city centers were qualified according to the results after reviewing both data from the survey and management.As a result,26 950 subjects including 12 450 asthmatic children and 14 500 control subjects were enrolled in the case-control study.Except for the children of Han ethnicity,another 5 980 children (22.2％) of ethnic minorities and 3 1 children (0.1 ％) born in foreign countries were also included as the study subjects.After controlling for city centers as random effect,age,sex,race,problems related to allergy,family history of asthma or allergy,personal medication history of antibiotics,preterm delivery,under caesarean section,baby age for introducing protein-contained foods,environmental tobacco smoking,maternal occupation,indoor plantings,room decorations,dampness,and cooking fuel were proved to be risk factors of childhood asthma.Some differences were seen in the risks of asthma between new cases and current cases.The risk for exposure to indoor plants was different between new cases (OR=2.09,95％CI1.30-3.36) and current cases (OR=0.80,95％ CI0.74-0.86).Risks on asthma were varied by age.Allergy,inflection,odor,and preterm delivery (OR=1.72,95％CI1.42-2.08) appeared to be the key risks for asthma in children younger than 3 years.Apart from the risks,specifically for children younger than 3 years,the risks on asthma for children of 3 to 5 years would also include factors assex (OR=1.18,95％CI1.03-1.35),low birth weight (OR=1.69,95％ CI1.17-2.44),and caesarean section (OR=1.26,95％ CI1.10-2.45).Apart from risks specifically for children younger than 6 years,age (OR=0.97,95％CI0.95-0.99),race (OR=1.61,95％CI1.26-2.06),and emigration (OR=1.68,95％CI1.39-2.03) were proved to be associated with asthma for children aged 6-14 years.Conclusion Asthma risks for city children in China would include genetic factors,allergy,infection,and other environmental factors but called for further research in the country.