Study objective: To investigate the early determinants and characteristics of different phenotypes of wheeze in children on the basis of questionnaire data, lung function, and prick tests.
Design: Cross-sectional survey. Setting. Rome and Fiumicino municipalities in Lazio region, Italy, within the ISAAC phase II project.
Subjects: Sample of 2107 9-11 year old schoolchildren (response rate 83.5%).
Results: We divided children into four mutually exclusive groups according to onset of wheeze: 154 early transient (birth to age 2), 51 persistent (birth to age 2 and current), 66 late onset (current only), and 1,446 control subjects (no early or current wheeze). Logistic regression models have shown that a family history of asthma and allergies is strongly associated with persistent and late onset wheezing; exposure to parental smoking--both during pregnancy and during the child's first year of life--is related to persistent wheezing; all children with wheezing show a significantly greater risk to have current respiratory symptoms other than wheeze compared with control subjects; current allergic rhinoconjunctivitis symptoms and atopy are related with both persistent and late onset wheeze. Multiple linear regression models show that forced expiratory rates at 25% to 75% of vital capacity (FEF25-75) and the ratio between forced expiratory volume in 1 second and forced vital capacity (FEV1/FVC) are significantly lower both in early transient (-305 mL/s, -1.7%) and persistent (-298 mL/s, -3.2%) wheezers; FEV1/FVC is significantly reduced in late onset wheezers too (-2.0%).
Conclusions: The strength of the association of family history and exposure to parental smoking varies with the three wheezing phenotypes. Moreover, early, persistent and late onset wheezers have different clinical characteristics in terms of their respiratory health and atopic status.