title: Relevance of birth cohorts to assessment of asthma persistence.
abstract: The definition of persistent asthma in longitudinal studies reflects symptoms reported at every assessment with no substantive asymptomatic periods. Early-childhood wheezing may be transient, especially if it is of viral etiology. Longitudinal studies provide greater opportunity to confirm the diagnosis by variability of symptoms, objective measurements, and therapeutic responses. Several clinical phenotypes of childhood asthma have been identified, with general consistency between cohorts. Persistent wheezing is often associated with loss of lung function, which is evident from early-childhood and related to persistent inflammation and airway hyperresponsiveness. Female sex, atopy, airway responsiveness, and personal smoking, but not exposure to environmental tobacco smoke, are risk factors for persistence of childhood asthma into adulthood. The effect of breastfeeding remains controversial, but gene-environment interactions may partly explain outcomes. Understanding the natural history and underlying causes of asthma may lead to development of strategies for primary prevention.
authors.affiliation: Department of Preventive and Social Medicine, Dunedin School of Medicine, University of Otago, New Zealand. bob.hancox@otago.ac.nz
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Hancox
authors.forename: Padmaja
authors.initials: P
authors.lastname: Subbarao
authors.forename: Malcolm R
authors.initials: MR
authors.lastname: Sears
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D001249:Asthma / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control*; D015984:Causality; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D015897:Comorbidity; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology*; D012074:Remission Induction; D012129:Respiratory Function Tests; D012135:Respiratory Sounds; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology*; D014028:Tobacco Smoke Pollution / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D014028:Tobacco Smoke Pollution