INTRODUCTION
The domestic cats (Felis catus) have long been known to be one of the most common respiratory allergens.1 Cat sensitivity rates vary between 20% and 50% in previous studies.2,3 Cat allergen is the second most frequent indoor allergen and the third most common among all aeroallergens after pollens and house dust mites.4 More than 350,000 emergency room visits occur due to cat allergy-related asthma attacks in the USA every year.5
Cat sensitization seems to be one of the most important risk factors for both the development of asthma and the rising frequency of asthma attacks.5,6,7 However, there are also some contradictory findings in the literature suggesting that cat sensitization may increase respiratory symptoms a non-linear manner with exposure or that intense exposure to cats at early ages may be even protective.8-12 Recent studies have shown that asthma severity, the frequency of wheezy attacks, medication requirements, and unpredictable physician visits due to allergic respiratory symptoms resulting from cat allergen exposure increase with cat sensitivity in children.13-16
Although conventional spirometry is a highly valuable test for detecting airway obstruction and diagnosing asthma, it is also subject to a number of limitations. Being effort-dependent and requiring high cooperation, it is difficult for children, particularly those of preschool-age. In addition, it does not provide sufficient information about peripheral airways.17 Impulse oscillometry (IOS) is a standardized, non-invasive, practical alternative test that requires less effort than spirometry. It is very useful for measuring entire and peripheral respiratory functions, particularly in preschool-age children unable to adapt to spirometry. IOS also provides important data regarding the deterioration in airway function that may develop in children with respiratory allergic diseases at early ages, and also yields more specific data about lung resistance, reactance, and peripheral airway obstruction.18,19
This study was set out to evaluate the respiratory function tests of children with cat sensitization and respiratory allergic diseases (asthma and/or allergic rhinitis) using IOS and spirometry, respectively, and to compare the resulting data with those of healthy controls, and also to evaluate the potential risk factors that may affect lung functions.