Overview of Studies
Table 1 describes all included economic evaluations. Of the 13 studies reviewed, four covered Europe (two The Netherlands, one England and Wales, and one Germany), eight covered North America (six USA and two Canada), and one covered Australia. Six were sponsored by the pharmaceutical industry (three GlaxoSmithKline and three Sanofi Pasteur) and seven were published by independent authors or government agencies, or did not report any industry funding. Twelve cost analyses, nine cost–effectiveness analyses and five cost–utility analyses (presenting cost per quality-adjusted life-year [QALY] and cost per disability-adjusted life-year [DALY] as outcomes) were conducted. Table 1 describes the 13 economic evaluations included in this review.
Nine studies considered adolescent booster vaccination. In The Netherlands approximately 20% of cases would be prevented, and the (incremental) cost per QALY would be between €4400 and €6400 according to De Vries et al., compared with no booster vaccination, from a societal perspective. In the USA, this strategy was estimated to cost US$6253 per life-year gained according to Caro et al., and US$20,000 per QALY gained according to Lee et al. from a societal perspective. Coudeville et al. predicted that adolescent booster vaccination dominated no booster vaccination, with a reduction of 77% in disease incidence; however, adolescent booster vaccination was dominated by broader booster vaccination strategies, including adult vaccination. In Quebec or in Ontario, the incremental cost of adolescent booster vaccination was less than CAD$600 per discounted pertussis case avoided, from the perspective of Ministry of Health, according to Iskedjian et al.[17,18] Edmunds et al. found that from the perspective of the healthcare provider, approximately 35% of the simulations resulted in a cost per life-year gained of less than GBP£10,000. Level of herd immunity and mortality rate were identified as key cost–effectiveness drivers.
Six studies considered one-time adult booster vaccination. In Germany, Lee et al. presented incremental cost–effectiveness ratio (ICERs) of €5800 per QALY saved from a societal perspective, with 10–12% of cases prevented. In the USA, Lee et al. estimated that only 1.4% of cases would be prevented and that this strategy would be dominated by absence of booster vaccination, since the detrimental impact of vaccine side effects on QALYs exceeded their benefits. Coudeville et al. considered a strategy combining childhood vaccination, adolescent booster, cocoon strategy and one booster dose at 40 years of age in the USA. Reduction in the overall incidence of symptomatic pertussis would be approximately 97% compared with childhood vaccination. A single booster dose at 40 years of age in addition to the cocoon strategy and adolescent booster was the dominant strategy compared with cocoon plus adolescent booster.
Six studies considered cocoon strategy (broadly defined as administering booster vaccines to household members of newborn infants). In The Netherlands, Westra et al. reported an ICER of €4600 per QALY from a third-party payer (TPP) perspective; this strategy would be cost-saving from the societal perspective. In a study by Lee et al., postpartum vaccination was found to be more costly than adolescent vaccination and would provide fewer health benefits. Coudeville et al. considered childhood vaccination combined with adolescent booster and cocoon strategy. Reduction in the overall incidence of symptomatic pertussis was approximately 80% compared with childhood vaccination only. This strategy dominated childhood vaccination combined with adolescent booster alone, but was dominated by broader vaccination strategies. In Australia, Scuffham et al. reported an ICER of AUS$787,504 per DALY avoided versus no current schedule, from a TPP perspective. This strategy could reduce pertussis cases, deaths and DALYs by 38.6, 38.2 and 38.3%, respectively. Nevertheless, it was not cost effective, and dominated by the at-birth vaccination strategy.
Four studies considered decennial adult booster vaccination. In Germany, Lee et al. reported an ICER of €7200 per QALY gained versus no booster vaccination, from a societal perspective. Between 20 and 25% of cases would be prevented depending on incidence data. In the USA, Lee et al. predicted that 5% of cases would be prevented, and this strategy was found to be dominated (as was the one-time adult vaccination strategy, due to adverse events). Coudeville et al. considered a strategy combining childhood vaccination, adolescent booster and a routine decennial adult vaccination in the USA. The overall incidence of symptomatic pertussis was predicted to decrease from 400 to 30 cases per 100,000 person-years, at a total cost per year of US$732,981 in a cohort of 1 million individuals from the societal perspective. The ICER of this strategy compared with 'adolescent booster + cocoon + one dose at 40 years' was very high (close to US$700,000 per QALY gained).
Other strategies were also considered. Maternal immunization, vaccination of specific populations (persons >18 years of age with chronic obstructive pulmonary disease, healthcare workers >20 years of age), and universal immunization appeared to be very cost effective. Immunization at birth was found not to be cost effective in base-case analysis because of the assumed limited vaccine effectiveness in infants, as stated by Westra et al. This finding was reinforced by the results presented by Scuffham et al. The authors also evaluated a strategy where infants would receive a vaccine dose at 1 month, the subsequent immunization schedule (2, 4 and 6 months) remaining unchanged. Table 2 presents final results for all studies and strategies considered. A detailed table providing all results (epidemiological, cost–effectiveness and economic impact) is provided in Supplementary Table 2.
Expert Rev Pharmacoeconomics Outcomes Res. 2012;12(1):71-94. © 2012 Expert Reviews Ltd.