title: Risk of invasive pneumococcal infections among working age adults with asthma.
abstract: BACKGROUND
  Information about the risk of invasive pneumococcal infection (IPI) among adults with asthma is limited and inconsistent. To evaluate this association, a population-based case-control study was conducted.
  
  
  METHODS
  Cases of IPI (Streptococcus pneumoniae isolated from blood or cerebrospinal fluid) were identified through national, population-based laboratory surveillance during 1995-2002. To maximise exclusion of chronic obstructive pulmonary disease, the analysis was limited to patients aged 18-49 years and 10 selected age-, sex- and health district-matched controls for each case from the Population Information System. Information on underlying medical conditions was obtained through linking surveillance data to other national health registries. Asthma requiring > or =1 hospitalisation in the past 12 months was defined as high risk asthma (HRA); low risk asthma (LRA) was defined as entitlement to prescription drug benefits and no hospitalisation for asthma in the past 12 months.
  
  
  RESULTS
  1282 patients with IPI and 12 785 control subjects were identified. Overall, 7.1% of cases and 2.5% of controls had asthma (6.0% and 2.4% had LRA whereas 1.1% and 0.1% had HRA, respectively. After adjustment for other independent risk factors in a conditional logistic regression model, IPI was associated with both LRA (matched OR (mOR) 2.8; 95% CI 2.1 to 3.6) and HRA (mOR, 12.3; 95% CI 5.4 to 28.0). The adjusted population-attributable risk was 0.039 (95% CI 0.023 to 0.055) for LRA and 0.01 (95% CI 0.0035 to 0.017) for HRA.
  
  
  CONCLUSIONS
  Working age adults with asthma are at increased risk of IPI. In this population, approximately 5% of disease burden could be attributed to asthma. These findings support adding medicated asthma in adults to the list of indications for pneumococcal vaccination.
authors.affiliation: Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Peter
authors.initials: P
authors.lastname: Klemets
authors.forename: Outi
authors.initials: O
authors.lastname: Lyytikäinen
authors.forename: Petri
authors.initials: P
authors.lastname: Ruutu
authors.forename: Jukka
authors.initials: J
authors.lastname: Ollgren
authors.forename: Tarja
authors.initials: T
authors.lastname: Kaijalainen
authors.forename: Maija
authors.initials: M
authors.lastname: Leinonen
authors.forename: J Pekka
authors.initials: JP
authors.lastname: Nuorti
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000150:complications* / Q000453:epidemiology; D004812:Epidemiologic Methods; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009894:Opportunistic Infections / Q000150:complications* / Q000453:epidemiology / Q000382:microbiology; D011008:Pneumococcal Infections / Q000150:complications* / Q000453:epidemiology / Q000382:microbiology; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification; D055815:Young Adult