In addition, potential interaction between atopy and infections for the adult-onset asthma was evaluated. == Methods == == Study design == This study was a population-based incident case-control study. acute bronchitis and pneumonia) with an adjusted odds ratio (OR) 7.18 (95% confidence interval [CI] 5.169.99), or upper respiratory tract infections (including common cold, sinusitis, tonsillitis, and otitis media) with an adjusted OR 2.26 (95% CI 1.722.97). Individuals with personal atopy and/or parental atopy were more susceptible to the effects of respiratory infections on asthma onset than non-atopic persons. == Conclusions/Significance == This study provides new evidence that recently experienced respiratory infections are a strong determinant for adult-onset asthma. Reducing such infections might prevent onset of asthma in adulthood, especially in individuals with atopy or hereditary propensity to it. == Introduction == Asthma is a chronic inflammatory disease of the airways characterized by reversible airflow obstruction[1]. It is among the most common chronic diseases in working-age adults with an average prevalence of 7.5% in Finland[2]and 7.3% in United States[3]. Respiratory infections may play a role in the etiology of asthma. Children who experience viral respiratory infections in early life are more likely to develop asthma later in childhood[4][7]. However, there is little data on the role of infections for onset of asthma in adults. Serologic evidence of chronicChlamydia pneumoniaeinfection has been linked to adult asthma[8],[9], but acute respiratory infections as determinants ARV-771 of adult-onset asthma have not been studied. However, there are plausible mechanisms by which infectious agents could contribute to induction of asthma[10],[11]. Respiratory infections cause airway epithelial damage and airway inflammation and initiate immune responses that further enhance airway inflammation. The objective of this study was to assess the relation between occurrence of respiratory infections in the past 12 months and onset of adult asthma in a population-based incident case-control study of a working age population. In addition, potential interaction between atopy and infections for the adult-onset asthma was evaluated. == Methods == == Study design == This study was a population-based incident case-control study. The source population consisted of adults 21 to 63 years of age living in the Pirkanmaa Hospital District, a geographically defined administrative area in South Finland (population 440 913 in 1997). We recruited all the new cases of asthma during a 2.5-year study period and randomly selected controls from the source population. All study subjects signed an informed consent form. The study was approved by the ethics committees of Rabbit polyclonal to ZNF248 the Finnish Institute of Occupational Health and the Tampere University Hospital. == Definition and selection of cases == We ARV-771 recruited systematically all the new cases of asthma 19972000 at all health care facilities diagnosing asthma in the Pirkanmaa ARV-771 Hospital district, including the Department of Pulmonary Medicine at the Tampere University Hospital, offices of the private-practicing pulmonary physicians in the region as well as public health care centers. As an additional route of case recruitment, the National Social Insurance Institution of Finland invited all patients, who had received reimbursement rights for asthma medication during our study period, but had not yet participated. The diagnostic criteria for asthma are given inTable 1[2],[12][19]. == Table 1. Diagnostic criteria for asthma. == FEV1= forced expiratory volume in one second; FVC = forced vital capacity; PEF = peak expiratory flow. Calculated according to the standard practice ARV-771 of the Tampere University Hospital: maximum daily variation = (highest PEF value during the day lowest PEF value during the day)/highest PEF value during the day; bronchodilator response = (highest PEF value after bronchodilating medication highest PEF value before medication)/highest PEF value before medication. The medical records of all cases were checked, and only those with no previously diagnosed asthma or long-term use of any asthma medication were included in the study to ensure that the cases had asthma diagnosed for the first time at recruitment. At the Tampere University Hospital, cases were recruited even before the diagnosis (at their first ARV-771 visit due to suspected asthma) and the diagnosis was then verified in clinical examinations. A total of 521 cases participated (response rate 86%). == Selection.