title: Increasing prevalence of asthma, respiratory symptoms, and allergic diseases: Four repeated surveys from 1993-2014.
abstract: BACKGROUND
  Published data shows different prevalence trends depending on the region of Europe.
  
  
  OBJECTIVE
  The aim of the study was to analyze time trends of the frequency of the respiratory symptoms and allergic diseases in school children (Silesia, Poland) over the last 21 years.
  
  
  METHODS
  We compared the results of four population-based surveys performed in a town of Chorzow in 1993, 2002, 2007 and 2014 in children aged 7-10 years. All four studies had the same study protocol, recruitment (cluster, school-based sampling), questionnaire (WHO respiratory health questionnaire) and the same principal investigator The surveys included 1130 children in 1993, 1421 children in 2002, 1661 children in 2007 and 1698 in 2014.
  
  
  RESULTS
  The results covered a 21 year span and showed a statistically significant (p < 0.05) increase in the prevalence of the following physician-diagnosed disorders (1993-2002-2007-2014): asthma (3.4%-4.8%-8.6%-12,6%); allergic rhinitis (4.3%-11.9%-15.9%-13.9%); atopic dermatitis (3.6%-7.9%-12.0%-13.9%); allergic conjunctivitis (4.3%-7.9%-8.3%-7.9%); A simultaneous increasing trend (p < 0.05) in the attacks of dyspnea (3.9%-5.9%-7.0%-7.3%) and symptoms (wheeze, dyspnea, cough) induced by exercise (7.5%-10.6%-22.0%-22.4%) and - at the same time - decrease (p < 0.05) in the prevalence of cough (31.6%-19.6%15.4%-14.4%). Among children with diagnosed asthma during the 21 year span there was significantly (p < 0.05) increased proportion of treated children (51.3%-51.3%-69.5%-60.7%) and a lower frequency of presenting current symptoms.
  
  
  CONCLUSIONS
  Our findings are in line with the concept of a real increase in the occurrence of asthma and allergic disease in children. The pattern involves not only physician-diagnosed allergic diseases but also occurrence of symptoms related to respiratory disorders. Diagnosed asthma is better treated and better controlled.
authors.affiliation: Department of Epidemiology, School of Medicine, Medical University of Silesia in Katowice, Medykow 18 Str, 40-752 Katowice, Poland. Electronic address: gbrozek@sum.edu.pl.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Brozek
authors.affiliation: Department of Medicine and Canadian Center for Health and Safety in Agriculture, University of Saskatchewan, 104 Clinic Place, PO Box 23, Saskatoon, SK S7N 2Z4, Canada. Electronic address: josh.lawson@usask.ca.
authors.forename: Joshua
authors.initials: J
authors.lastname: Lawson
authors.affiliation: Department of Epidemiology, School of Medicine, Medical University of Silesia in Katowice, Medykow 18 Str, 40-752 Katowice, Poland. Electronic address: dawid_szumilas@wp.eu.
authors.forename: Dawid
authors.initials: D
authors.lastname: Szumilas
authors.affiliation: Department of Epidemiology, School of Medicine, Medical University of Silesia in Katowice, Medykow 18 Str, 40-752 Katowice, Poland. Electronic address: jzejda@sum.edu.pl.
authors.forename: Jan
authors.initials: J
authors.lastname: Zejda
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000453:epidemiology*; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology*; D008297:Male; D011044:Poland / Q000453:epidemiology; D011159:Population Surveillance / Q000379:methods*; D015995:Prevalence; D012189:Retrospective Studies
keywords: Allergic diseases; Asthma; Children; Epidemiology; Respiratory symptoms; Trend