Background: Asthma prevalence has increased in developed and developing countries in several last decades. Although cigarette smoking is an identified risk factor for many diseases such as coronary Heart disease and chronic obstructive lung disease, its effect on asthma is controversial. The aim of this study was to determine the odds ratio and its confidence interval for asthma morbidity among children referred to the Immunology and Allergy department of children medical center according to their parents' smoking and daily cigarette consumption.
Methods: A case-control study was conducted during two years period on the asthmatic patients who referred to Immunology and Allergy department of children medical center. Demographic information and parents' smoking and daily cigarette consumption assessed by a questionnaire. Healthy children with same age and sex were entered to the study as the control group. Statistical analysis was performed to calculate odds ratio.
Results: Among 215 patients who entered the study 63 patients were exposed the cigarette smoke. Odds ratio for asthma morbidity among children whose parents smoke more than five cigarettes per day in comparison with whose smoke less than five or do not smoke was 2.38 (p<0.01).
Conclusion: Parent's cigarette smoking is a risk factor for childhood asthma and could increase the risk of asthma to 2.38 folds in children whose parents smoke more than five cigarettes. Increasing in parents' knowledge level that probably relate to their education results in cigarette consumption decline.