title: A prospective study of asthma incidence and its predictors: the RHINE study.
abstract: The objective of this longitudinal study was to estimate the incidence rate of asthma, and to compare the incidence between subjects with or without baseline reporting of certain respiratory symptoms. A follow-up of the random population samples in the European Respiratory Health Survey (ECRHS) in Sweden, Norway, Denmark, Iceland and Estonia was conducted in 1999-2001, in a population aged 30-54 yrs at follow-up (n=14,731). Asthma was defined as reporting either asthma or physician-diagnosed asthma, and a reported year when asthma symptoms were first noticed. Incidence rates, incidence rate ratios and hazard ratios were calculated with 95% confidence intervals. The incidence rate of asthma was 2.2 cases per 1,000 person-yrs. The incidence was higher among females (2.9 cases.1,000 person-yrs(-1)) than among males (1.5 cases.1,000 person-yrs(-1)). When subjects with baseline reporting of wheezing were excluded, the incidence rate decreased to 1.7 cases.1,000 person-yrs(-1), with a further decrease to 1.5 cases.1,000 person-yrs(-1) after exclusion of subjects with wheezing, nocturnal dyspnoea, chest tightness and cough. There was a strong association between onset of asthma and wheezing at baseline. In this prospective, population-based study, the incidence rate of asthma in the whole population sample ranged 1.5-2.2.1,000 person-yrs(-1), with a higher incidence range among females. The incidence was dependent on the extent to which subjects with respiratory symptoms were excluded from follow-up. Hence, for comparability between studies, the exclusion criteria in the follow-up population must be stated.
authors.affiliation: Dept of Occupational and Environmental Medicine, S:t Sigfridsgatan 85B, S-412 66 Göteborg, Sweden. Kjell.Toren@ymk.gu.se
authors.forename: K
authors.initials: K
authors.lastname: Torén
authors.forename: T
authors.initials: T
authors.lastname: Gislason
authors.forename: E
authors.initials: E
authors.lastname: Omenaas
authors.forename: R
authors.initials: R
authors.lastname: Jögi
authors.forename: B
authors.initials: B
authors.lastname: Forsberg
authors.forename: L
authors.initials: L
authors.lastname: Nyström
authors.forename: A-C
authors.initials: AC
authors.lastname: Olin
authors.forename: C
authors.initials: C
authors.lastname: Svanes
authors.forename: C
authors.initials: C
authors.lastname: Janson
mesh_terms: D000328:Adult; D001249:Asthma / Q000453:epidemiology* / Q000503:physiopathology; D016009:Chi-Square Distribution; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires