title: Early Respiratory Infections and the Development of Asthma in the First 27 Years of Life.
abstract: Previous studies have provided contradictory evidence on the role of early childhood respiratory infections in the development of asthma and other allergic diseases during childhood. We investigated early-life respiratory infections as predictors of the development of asthma in a 20-year prospective cohort study (the Espoo Cohort Study, 1991-2011). Information on upper respiratory tract infections (URTIs) and lower respiratory tract infections (LRTIs) was collected with a parent-administered baseline questionnaire covering the preceding 12 months (part 1; n = 2,228), and information on LRTIs leading to hospitalization was obtained from the National Hospital Discharge Registry (part 2; n = 2,568). The incidence of asthma was assessed on the basis of 6-year and 20-year follow-up questionnaires. Adjusted hazard ratios were estimated using Cox proportional hazards models. Both URTIs (adjusted hazard ratio (HR) = 1.64, 95% confidence interval (CI): 1.22, 2.19) and LRTIs (adjusted HR = 2.11, 95% CI: 1.48, 3.00) in early childhood were strong predictors of asthma incidence up to young adulthood (ages 20-27 years). A declining age trend was present for both URTIs (P-trend < 0.01) and LRTIs (P-trend < 0.001). In part 2 of our analysis, a significant risk of asthma was found in relation to LRTIs requiring hospitalization (adjusted HR = 1.93, 95% CI: 1.10, 3.38). The results provide new evidence that respiratory tract infections in early life predict the development of asthma through childhood to young adulthood.
authors.forename: Aino K
authors.initials: AK
authors.lastname: Rantala
authors.forename: Maritta S
authors.initials: MS
authors.lastname: Jaakkola
authors.forename: Elina M S
authors.initials: EM
authors.lastname: Mäkikyrö
authors.forename: Timo T
authors.initials: TT
authors.lastname: Hugg
authors.forename: Jouni J K
authors.initials: JJ
authors.lastname: Jaakkola
mesh_terms: D001249:Asthma / Q000453:epidemiology* / Q000209:etiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D006760:Hospitalization; D006801:Humans; D007223:Infant; D008297:Male; D011446:Prospective Studies; D012141:Respiratory Tract Infections / Q000150:complications / Q000453:epidemiology*
keywords: asthma; cohort studies; early childhood respiratory infections; hygiene hypothesis; proportional hazards model; respiratory tract