PARENTAL SMOKING AND OTHER RISK-FACTORS FOR WHEEZING BRONCHITIS IN CHILDREN

A population-based case-control study was performed to investigate eti ologic factors for wheezing bronchitis and asthma in children up to fo ur years of age. A total of 199 children hospitalized for the first ti me with these diagnoses at a major hospital in Stockholm in 1986-1988 constituted the cases, 351 children from the catchment area of the hos pital were used as controls. Information on known and suspected risk f actors was obtained through home interviews with a parent. Parental sm oking was associated with a relative risk of 1.8 (95% confidence inter val 1.3 - 2.6) corresponding to a population attributable proportion o f 27%. The strongest association was seen for maternal smoking and chi ldren below 18 months of age. Other major risk factors included atopic heredity, recurrent upper respiratory tract infections and breast-fee ding less than 3 months, which appeared to interact multiplicatively w ith parental smoking. The environmental factors had a stronger influen ce in the youngest age group, and the overall attributable proportion associated with parental smoking, short breast-feeding period and expo sure to pets in the household was 43%. It is clear that successful pri mary prevention could dramatically reduce the incidence of wheezing br onchitis in children.