Early life lung function and respiratory outcome in the first year of life.

Abnormal early life lung function is related to wheezing in childhood; however, data on the association with cough are not available. We determined the relationship between early life lung function and wheeze and cough during the first year of life, adjusted for other possible risk factors. Infants were participants of the Wheezing Illnesses Study Leidsche Rijn (WHISTLER). Lung function measurements were performed before the age of 2 months. Information on pre- and perinatal factors, general characteristics and anthropometrics were assessed by questionnaires. Follow-up data on respiratory symptoms were assessed by daily questionnaires. 836 infants had valid lung function measurements and complete follow-up data for respiratory symptoms at 1 yr of age. Multivariable Poisson analysis showed that higher values of respiratory resistance (R(rs)) and time constant (τ(rs)) were associated with an increased risk for wheeze and cough during the first year of life. Higher values of respiratory compliance (C(rs)) were associated with a decreased risk for wheeze and cough. R(rs), C(rs) and τ(rs) measured shortly after birth were independently associated with wheeze and cough during the first year of life. As the strength of the relationships were different for wheeze and cough, they should be used as two separate entities.