Investigation of passive smoking effects on children under the age of five who were admitted to a teaching hospital with the diagnosis of lower respiratory infection.

New born babies, fetus and infants are more susceptible to the adverse effects of passive smoking compared with older children and adults. It is known that passive cigarette smoking causes lower respiratory tract infections (LTRI) more frequently in infancy and childhood period. The aim of this study was to investigate the effect of passive smoking on children under the age of five admitted to a teaching hospital with a diagnosis of LTRI.The study was designed as a case-control study. In our study, 55 cases under the age of five with a diagnosis of LTRI and 56 patients under the age of five with other complaints except LTRI as a control group admitted to a teaching hospital were selected. Case and control group were investigated for the effect of passive smoking exposure. A questionnaire including demographic feature of children, parents' smoking status and questions about the clinical diagnosis and symptoms of LTRI was performed for parents by using the face to face interview technique. Serum total immunoglobulin E (IgE), serum cotinine level, eosinophil count in blood per mm³ were assessed both in case and control group.The mean age of children was 24.8±15.6 months (range 2 to 60), there were 54 girls (48,7%) and 57 boys (51,3%). Mothers? smoking rate and smoking cessation rate were 30,6% and 17,6% respectively. Age of smoking onset for mothers was 17.5±3.5 years. Fathers? smoking rate and smoking cessation rate was 82,9% and 8,7% respectively. Age of smoking onset for fathers was 16.5±3.1 years. The frequency of smoking around children was 67,9% and 69% for active smoking mothers and fathers respectively. Exposure to cigarette smoke (p:0.628), serum total IgE (p:0.265) and serum cotinine level (p:0.265) were similar both in case and control group. Serum total IgE (p:0.0001), serum cotinine level (p:0.033) and eosinophil count (p:0.032) were found significantly higher in children exposed to smoking in their homes compared with non-exposures. There was a strong association between serum cotinine level and the amount of smoking around children (p: 0.013, spearman?s rho: 0.318), while no association was found for total IgE level (p: 0.450, spearman?s rho: 0.099) and eosinophil count (p: 0.130, spearman?s rho: 0.198). In the current study, a proportional correlation was found between serum cotinine level and total IgE (p: 0.046, spearman?s rho:0.190). Similar correlation was also found between total IgE and eosinophil count (p:0.020, spearman?s rho:0.221). The mean cotinine level, with a 87% sensitivity and 80.8% specificity, was found above 0.9 ng/mLIn conclusion, passive smoking exposure rate of children under the age of five admitted to our teaching hospital was found to be significantly higher both in case and control group. There was no significant effect of passive smoking on lower tract respiratory infections. Parents? smoking, the amount of smoking and smoking at home or around children were found to be effects on the cotinine level of children. Thus, all individuals, especially parents, should be educated and informed about the adverse effects of passive smoking on fetus, babies and children.Key Words: children, passive smoking, lower tract respiratory infection, cotinine, total IgE, eosinophil