title: Risk and outcomes of invasive pneumococcal disease in adults with underlying conditions in the post-PCV7 era, The Netherlands.
abstract: BACKGROUND
  Immunocompromising conditions and advanced age (≥65 years) are associated with a high risk for invasive pneumococcal disease (IPD). We investigated the risk and outcomes of IPD in adults with underlying conditions in the post-PCV7 era in The Netherlands.
  
  
  METHODS
  IPD data from 2008 to 2012 was obtained from the national pneumococcal surveillance system, covering 25% of the Dutch population. Population estimates of underlying conditions were derived from the primary care data (2012). IPD incidence in adults with immunocompromising conditions (high risk group) and non-immunocompromising comorbidities (medium risk group) were compared to the "normal risk group" without diagnosed comorbidities. Case-fatality and ICU admission in the different risk groups was analyzed by logistic regression. Serotype specific propensities to affect high risk group IPD patients were calculated.
  
  
  RESULTS
  Adults with a high risk condition have a 18-fold (95% CI 15.6-21.2) and 3-fold (95% CI 2.6-3.9) higher risk compared to the normal risk group for IPD at age 18-64 years and 65 years and older, respectively. In case of a medium risk condition, the risk is 5-fold (95% CI 4.3-5.7) and 2-fold (95% CI 1.9-2.6) higher in age groups 18-64 and ≥65 years old. Likewise, IPD patients with a high or medium risk condition have a higher case-fatality (after adjustment for age, odds ratio: 2-fold (95% CI 1.5-3.5) and 1.4-fold (95% CI 1.0-2.1), respectively). Several serotypes (e.g. 6A, 6B, 23A and 23B) are associated with a significantly higher propensity to cause disease in high risk patients.
  
  
  CONCLUSIONS
  The risk for IPD and death in the post-PCV7 era has remained considerably high in adults and elderly with underlying conditions. The identification of serotypes with a high propensity to affect risk groups can be important for selecting (future) vaccine serotypes.
authors.affiliation: Department of Medical Microbiology and Immunology, St. Antonius Hospital, Nieuwegein, The Netherlands. Electronic address: wagenvoort@gmail.com.
authors.forename: Gertjan H J
authors.initials: GH
authors.lastname: Wagenvoort
authors.affiliation: Centre for Infectious Disease Control Netherlands (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Mirjam J
authors.initials: MJ
authors.lastname: Knol
authors.affiliation: Centre for Infectious Disease Control Netherlands (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Hester E
authors.initials: HE
authors.lastname: de Melker
authors.affiliation: Department of Medical Microbiology and Immunology, St. Antonius Hospital, Nieuwegein, The Netherlands.
authors.forename: Bart J
authors.initials: BJ
authors.lastname: Vlaminckx
authors.affiliation: Department of Medical Microbiology and The Netherlands Reference Laboratory for Bacterial Meningitis, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Arie
authors.initials: A
authors.lastname: van der Ende
authors.affiliation: Pfizer bv., RiviumWestlaan 142, 2909 LD Capelle a/d IJssel, The Netherlands; Department of Pharmacy, Unit of PharmacoEpidemiology & PharmacoEconomics (PE2), University of Groningen, Groningen, The Netherlands.
authors.forename: Mark H
authors.initials: MH
authors.lastname: Rozenbaum
authors.affiliation: Centre for Infectious Disease Control Netherlands (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands; Department of Immunology and Infectious Diseases, University Medical Center Utrecht, Wilhelmina Children's Hospital, Utrecht, The Netherlands.
authors.forename: Elisabeth A M
authors.initials: EA
authors.lastname: Sanders
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000453:epidemiology / Q000382:microbiology / Q000401:mortality / Q000517:prevention & control; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine / Q000008:administration & dosage* / Q000276:immunology*; D006801:Humans; D008297:Male; D016920:Meningitis, Bacterial / Q000453:epidemiology / Q000382:microbiology / Q000401:mortality / Q000517:prevention & control; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality / Q000517:prevention & control*; D018570:Risk Assessment; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000145:classification / Q000302:isolation & purification*; D016019:Survival Analysis; D055815:Young Adult
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine
keywords: Clinical outcome; Comorbidity; Invasive pneumococcal disease; Pneumococcal conjugate vaccine; Serotypes; Streptococcus pneumoniae; Surveillance