Effects of exposure to parental smoking on pulmonary function and symptoms in children with asthma

Exposure to parental smoking (EPS) has been associated with increased asthma symptoms and airway hyperreactivity. Aim of the present study was to evaluate prospectively the effects of EPS on pulmonary function and symptoms in children with asthma. Methods: Urine cotinine-to-creatinine ratio (UCCRR) was used as an indirect measure of EPS, while FEV1 and asthma exacerbations were the main outcome variables. Subjects were evaluated at baseline and 2 years after an intervention to eliminate EPS. Results: 78 children (6-14 y.o.) were recruited. Subjects with history of EPS (n=38) had significantly lower FEV1 and higher UCCRR compared to those without such history (90.6±11.1 vs 96.4±12.6% predicted, p=0.046; and 25.3±21.3 vs. 14.1±11.7 ng/mg; p=0.005). Two years later, 31 children were re-evaluated; subjects with a decrease in UCCRR were similar regarding FEV1 compared to those with an increase in UCCRR (100.1±9.4 vs. 105.4±14.7% predicted, p=0.299). However, there was a trend for reduced frequency of asthma exacerbations: from 3.2±2.1/year to 0.7±1.1, p=0.073 in children with reduced UCCRR. Conclusions: History of EPS is associated with decreased airway function. Reduction in urinary cotinine levels within 2 years is accompanied by a trend for improvement in asthma exacerbations but not in airway function.