title: Diverging trends of chronic bronchitis and smoking habits between 1998 and 2010.
abstract: BACKGROUND
  No study has been carried out on the time trend in the prevalence of chronic bronchitis (CB) in recent years, despite its clinical and epidemiological relevance. We evaluated the trend in CB prevalence during the past decade among young Italian adults.
  
  
  METHODS
  A screening questionnaire was mailed to general population samples of 20-44 year-old subjects in two cross-sectional surveys: the Italian Study on Asthma in Young Adults (ISAYA) (1998/2000; n = 18,873, 9 centres) and the screening stage of the Gene Environment Interactions in Respiratory Diseases (GEIRD) study (2007/2010; n = 10,494, 7 centres). CB was defined as having cough and phlegm on most days for a minimum of 3 months a year and for at least 2 successive years. The prevalence rates and the risk ratios (RRs) for the association between CB and each potential predictor were adjusted for gender, age, season of response, type of contact, cumulative response rate, and centre.
  
  
  RESULTS
  CB prevalence was 12.5% (95% CI: 12.1-12.9%) in 1998/2000 and 12.6% (95% CI: 11.7-13.7%) in 2007/2010; it increased among never smokers (from 7.6 to 9.1%, p = 0.003), current light smokers (<15 pack-years; from 15.1 to 18.6%, p < 0.001), and unemployed/retired subjects (from 14.3 to 19.1%, p = 0.001). In this decade, the prevalence of current smoking decreased (from 33.6 to 26.9%, p < 0.001), whereas the prevalence of unemployment/premature retirement (from 5.3 to 6.0%, p = 0.005), asthma (from 5.0 to 6.2%, p = 0.003), and allergic rhinitis (from 19.5 to 24.5%, p < 0.001) increased. In both 1998/2000 and 2007/2010, the likelihood of having CB was significantly higher for women, current smokers, asthmatic patients, and subjects with allergic rhinitis. During this period, the strength of the association between CB and current heavy smoking (≥15 pack-years) decreased (RR: from 4.82 to 3.57, p = 0.018), whereas it increased for unemployment/premature retirement (from 1.11 to 1.53, p = 0.019); no change was observed for gender, asthma, and allergic rhinitis.
  
  
  CONCLUSIONS
  Despite the significant reduction in current smoking, CB prevalence did not vary among young Italian adults. The temporal pattern of CB prevalence can only be partly explained by the increase of unemployment/premature retirement, asthma and allergic rhinitis, and suggests that other factors could have played a role.
authors: Unit of Epidemiology and Medical Statistics, Department of Public Health and Community Medicine, University of Verona, c/o Istituti Biologici II, Strada Le Grazie 8, 37134, Verona, Italy. simone.accordini@univr.it
authors: Simone
authors: S
authors: Accordini
authors: Angelo Guido
authors: AG
authors: Corsico
authors: Isa
authors: I
authors: Cerveri
authors: Leonardo
authors: L
authors: Antonicelli
authors: Francesco
authors: F
authors: Attena
authors: Roberto
authors: R
authors: Bono
authors: Lucio
authors: L
authors: Casali
authors: Marcello
authors: M
authors: Ferrari
authors: Alessandro
authors: A
authors: Fois
authors: Pierpaolo
authors: P
authors: Marchetti
authors: Pietro
authors: P
authors: Pirina
authors: Roberta
authors: R
authors: Tassinari
authors: Giuseppe
authors: G
authors: Verlato
authors: Roberto
authors: R
authors: de Marco
mesh_terms: D000328:Adult; D001249:Asthma / Q000175:diagnosis / Q000453:epidemiology; D029481:Bronchitis, Chronic / Q000175:diagnosis / Q000453:epidemiology*; D003430:Cross-Sectional Studies / Q000639:trends; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D065631:Rhinitis, Allergic; D012221:Rhinitis, Allergic, Perennial / Q000175:diagnosis / Q000453:epidemiology; D012907:Smoking / Q000453:epidemiology* / Q000639:trends*; D055815:Young Adult
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