title: Cost-effectiveness analysis of Tdap in the prevention of pertussis in the elderly.
abstract: OBJECTIVE
  Health benefits and costs of combined reduced-antigen-content tetanus, diphtheria, and pertussis (Tdap) immunization among adults ≥65 years have not been evaluated. In February 2012, the Advisory Committee on Immunization Practices (ACIP) recommended expanding Tdap vaccination (one single dose) to include adults ≥65 years not previously vaccinated with Tdap. Our study estimated the health and economic outcomes of one-time replacement of the decennial tetanus and diphtheria (Td) booster with Tdap in the 10% of individuals aged 65 years assumed eligible each year compared with a baseline scenario of continued Td vaccination.
  
  
  METHODS
  We constructed a model evaluating the cost-effectiveness of vaccinating a cohort of adults aged 65 with Tdap, by calculating pertussis cases averted due to direct vaccine effects only. Results are presented from societal and payer perspectives for a range of pertussis incidences (25-200 cases per 100,000), due to the uncertainty in estimating true annual incidence. Cases averted were accrued throughout the patient 's lifetime, and a probability tree used to estimate the clinical outcomes and costs (US$ 2010) for each case. Quality-adjusted life-years (QALYs) lost to acute disease were calculated by multiplying cases of mild/moderate/severe pertussis by the associated health-state disutility; QALY losses due to death and long-term sequelae were also considered. Incremental costs and QALYs were summed over the cohort to derive incremental cost-effectiveness ratios. Scenario analyses evaluated the effect of alternative plausible parameter estimates on results.
  
  
  RESULTS
  At incidence levels of 25, 100, 200 cases/100,000, vaccinating adults aged 65 years costs an additional $336,000, $63,000 and $17,000/QALY gained, respectively. Vaccination has a cost-effectiveness ratio less than $50,000/QALY if pertussis incidence is >116 cases/100,000 from societal and payer perspectives. Results were robust to scenario analyses.
  
  
  CONCLUSIONS
  Tdap immunization of adults aged 65 years according to current ACIP recommendations is a cost-effective health-care intervention at plausible incidence assumptions.
authors.affiliation: OptumInsight, Cambridge, Massachusetts, United States of America.
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: McGarry
authors.forename: Girishanthy
authors.initials: G
authors.lastname: Krishnarajah
authors.forename: Gregory
authors.initials: G
authors.lastname: Hill
authors.forename: Michelle
authors.initials: M
authors.lastname: Skornicki
authors.forename: Narin
authors.initials: N
authors.lastname: Pruttivarasin
authors.forename: Cristina
authors.initials: C
authors.lastname: Masseria
authors.forename: Bhakti
authors.initials: B
authors.lastname: Arondekar
authors.forename: Stephen I
authors.initials: SI
authors.lastname: Pelton
authors.forename: Milton C
authors.initials: MC
authors.lastname: Weinstein
mesh_terms: D000368:Aged; D015331:Cohort Studies; D003362:Cost-Benefit Analysis; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000008:administration & dosage / Q000191:economics / Q000627:therapeutic use*; D006801:Humans; D014917:Whooping Cough / Q000517:prevention & control*
chemical_list: D015721:Diphtheria-Tetanus-Pertussis Vaccine
references.citation: Natl Vital Stat Rep. 2010 Jun 28;58(21):1-40
references.pmid: 21043319
references.citation: MMWR Recomm Rep. 2006 Mar 24;55(RR-3):1-34
references.pmid: 16557217
references.citation: Vital Health Stat 11. 2009 Apr;(249):1-68
references.pmid: 19642512
references.citation: Health Serv Res. 2004 Jun;39(3):627-42
references.pmid: 15149482
references.citation: Dig Dis Sci. 2004 Mar;49(3):453-8
references.pmid: 15139497
references.citation: Proc Natl Acad Sci U S A. 2011 May 3;108(18):7279-80
references.pmid: 21508325
references.citation: JAMA. 1996 Jan 3;275(1):37-41
references.pmid: 8531284
references.citation: Med Decis Making. 2006 Jul-Aug;26(4):391-400
references.pmid: 16855127
references.citation: J Infect. 2006 Aug;53(2):106-13
references.pmid: 16352342
references.citation: PLoS One. 2010 Oct 15;5(10):e13392
references.pmid: 20976213
references.citation: Vaccine. 2007 Nov 28;25(49):8326-37
references.pmid: 17980938
references.citation: Arch Fam Med. 2000 Nov-Dec;9(10):989-96
references.pmid: 11115197
references.citation: Am J Prev Med. 2007 Mar;32(3):186-193
references.pmid: 17296470
references.citation: Vaccine. 2007 Jun 28;25(27):5086-96
references.pmid: 17544181
references.citation: Am J Prev Med. 2007 Mar;32(3):177-185
references.pmid: 17296469
references.citation: JAMA. 2012 Feb 22;307(8):804-12
references.pmid: 22357831
references.citation: Pediatr Infect Dis J. 2005 May;24(5 Suppl):S75-82
references.pmid: 15876932
references.citation: Clin Infect Dis. 2004 Dec 1;39(11):1572-80
references.pmid: 15578353
references.citation: J Health Econ. 1997 Feb;16(1):33-64
references.pmid: 10167344
references.citation: BMC Infect Dis. 2005 Jul 11;5:57
references.pmid: 16008838
references.citation: MMWR Morb Mortal Wkly Rep. 2011 Jan 14;60(1):13-5
references.pmid: 21228763