|Childhood vaccination against pneumococcal otitis media and pneumonia: an analysis of benefits and costs
|Weycker D, Richardson E, Oster G
This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn.
The use of a heptavalent pneumococcal conjugate vaccine (PNCRM7) in children aged younger than 5 years, for the prevention of acute otitis media (AOM), community-acquired pneumonia (CAP), and tympanostomy and related procedures (TRP).
Type of intervention
Primary prevention (paediatric vaccination).
Economic study type
The study population comprised children aged younger than 5 years.
The setting was the community. The economic study was carried out in the USA.
Dates to which data relate
The effectiveness and resource use data were gathered from 1996 to 2000. The price year was 1999.
Source of effectiveness data
The effectiveness evidence was derived from published studies. In addition, the authors made assumptions about the effectiveness.
A model of the risks and the economic costs of AOM, TRP and CAP was used to examine the economic consequences of routine childhood vaccination. The model included 7 hypothetical cohorts of 1,000 children each, who either did or did not receive the vaccine. The 7 cohorts corresponded to children of age less than 7, 7 to 11, 12 to 17, 18 to 23, 24 to 35, 36 to 47, and 48 to 59 months. The time horizon of the model was 10 years.
Outcomes assessed in the review
The outcomes assessed from the literature were also used as inputs for the model. The following outcomes were assessed:
the safety and efficacy of the vaccine, measured in terms of the percentage reduction in the number of cases of AOM, TRP and CAP;
the age-specific estimates of the expected number of cases of AOM, TRP and CAP, with or without the PNCRM7; and
the number of cohort members remaining alive at each age.
Study designs and other criteria for inclusion in the review
One of the primary studies was a large randomised clinical trial. The remaining primary studies used data derived from official sources (the US National Center for Health Statistics) and from a large health plan in New England (July 1, 1997 to June 30, 1998).
Sources searched to identify primary studies
Criteria used to ensure the validity of primary studies
Methods used to judge relevance and validity, and for extracting data
Number of primary studies included
The effectiveness evidence was derived from three published studies.
Methods of combining primary studies
Investigation of differences between primary studies
Results of the review
The only data derived from the literature related to the vaccine efficacy for children of age 0 to 23 months. The vaccine efficacy was 7% for AOM, 20.3% for TRP, and 11% for CAP.
Methods used to derive estimates of effectiveness
The authors made some assumptions in the model, due to the limited data available on the efficacy of paediatric vaccines.
Estimates of effectiveness and key assumptions
The main assumption made by the authors in the analysis was that, for children aged 0 to 23 months at the initial vaccination, the protective efficacy of the vaccine would persist to 10 years of age. However, from age 5 to 10 years, it was assumed that the vaccine efficacy would decline by half. For children aged 24 to 59 months at vaccination, it was assumed that the vaccine efficacy was the same as that in the younger cohort for the first 3 years, after which it would decline by half to age 10 years.
Measure of benefits used in the economic analysis
The benefit measure used in the economic analysis was the expected number of cases of AOM, TRP and CAP, with or without the PNCRM7. This was derived from the effectiveness analysis by multiplying the age-specific estimates of the expected numbers of cases per child, by the estimated number of cohort members remaining alive at each age.
The costs were discounted at a rate of 3%, because the time horizon of the study was 10 years. The cost/resource boundary adopted was that of a society. The cost analysis included expenses for the medical treatment, such as outpatient services, prescription medication, and hospitalisation. The quantities of the resources used and the unit costs were reported separately for the vaccines used in the study. The costs were estimated using actual data derived from official prices and from a published study. The resources were estimated from the manufacturer's recommendation and the data from the New England health plan (from July 1, 1997 to June 30, 1998). All the costs were adjusted to 1999 using the medical care component of the Consumer Price Index.
Statistical analysis of costs
No statistical analysis of the costs was reported.
The analysis included the illness-related work lost by the children' parents. The time spent away from work for the care of a sick child was valued through the parent's wage rate. The indirect costs were discounted at 3%. The value of the work lost, which was attributable to episodes of AOM, TRP and CAP, was reported. The indirect costs were estimated from interviews with the parents, which were reported in a published study.
One-way sensitivity analyses were conducted to assess the effect on "net economic benefit" (incremental cost) of variations in the following model inputs:
the duration of efficacy of the vaccine (50%, 150%);
the expected number of cases of AOM, TRP and CAP at each age (50%, 150%);
the estimate cost of medical care and parental work loss (50%, 150%); and
the cost of vaccine administration ($13).
Estimated benefits used in the economic analysis
The estimated numbers of cases of AOM in vaccinated and non-vaccinated children were:
4,765 and 5,066 for the age class less than 7 months;
4,670 and 5,000 for the age class 7 to 11 months;
4,371 and 4,683 for the age class 12 to 17 months;
3,826 and 4,093 for the age class 18 to 23 months;
3,286 and 3,508 for the age class 24 to 35 months;
2,508 and 2,681 for the age class 36 to 47 months; and
1,920 and 2,059 for the age class 48 to 59 months.
The estimated numbers of cases of TRP in vaccinated and non-vaccinated children were:
102 and 123 for the age class less than 7 months;
102 and 124 for the age class 7 to 11 months;
99 and 121 for the age class 12 to 17 months;
86 and 104 for the age class 18 to 23 months;
69 and 83 for the age class 24 to 35 months;
50 and 61 for the age class 36 to 47 months; and
39 and 47 for the age class 48 to 59 months.
The estimated numbers of cases of CAP in vaccinated and non-vaccinated children were:
303 and 333 for the age class less than 7 months;
272 and 300 for the age class 7 to 11 months;
259 and 286 for the age class 12 to 17 months;
241 and 267 for the age class 18 to 23 months;
221 and 244 for the age class 24 to 35 months;
180 and 199 for the age class 36 to 47 months; and
139 and 154 for the age class 48 to 59 months.
The average cost of the vaccine was $52 per dose and physicians charged $5 for the administration.
The value of the work lost was $182 for episodes attributable to AOM, $461 for those attributable to TRP, and $274 for those attributable to CAP.
The total costs of the vaccination programme were:
$226,000 for the age class less than 7 months;
$169,000 for the age class 7 to 11 months;
$114,000 for the age class 12 to 17 months;
$114,000 for the age class 18 to 23 months; and
$57,000 for the age classes 24 to 35 months, 36 to 47 months, and 48 to 59 months.
The cost-savings (in terms of both the direct and indirect costs), in relation to vaccine implementation and the reduction in the rates of AOM, TRP and CAP, were:
$138,000 ($71,000 and $67,000) for the age class less than 7 months;
$135,000 ($69,000 and $66,000) for the age class 7 to 11 months;
$129,000 ($67,000 and $62,000) for the age class 12 to 17 months;
$109,000 ($56,000 and $53,000) for the age class 18 to 23 months;
$88,000 ($44,000 and $44,000) for the age class 24 to 35 months;
$69,000 ($34,000 and $35,000) for the age class 36 to 47 months; and
$56,000 ($28,000 and $28,000) for the age class 48 to 59 months.
Therefore, the expected net economic benefit (the cost-savings minus the costs) of vaccination would be:
-$88,000 for the age class less than 7 months;
-$34,000 for the age class 7 to 11 months;
$15,000 for the age class 12 to 17 months;
-$5,000 for the age class 18 to 23 months;
$31,000 for the age class 24 to 35 months;
$12,000 for the age class 36 to 47 months; and
-$1,000 for the age class 48 to 59 months.
Synthesis of costs and benefits
The costs and the benefits were not combined. Sensitivity analyses indicated that for those scenarios favouring vaccination, the net economic benefits were generally positive in each age group, except for those who where 0 to 11 months of age. For those scenarios biased against vaccination, the net economic benefit was generally negative.
The vaccination programme in children younger than 5 years led to a substantial reduction in the expected number of cases of acute otitis media (AOM), community-acquired pneumonia (CAP), and tympanostomy and related procedures (TRP). It also substantially reduced the related costs of medical treatment and work loss. In particular, the programme appeared to "be cost increasing for children less than 2 years of age who required multiple doses, but cost-saving for those aged 2 to 5 years, who would require only a single dose of vaccine".
CRD COMMENTARY - Selection of comparators
The reason for the selection of the comparator was not entirely clear. It appears that the choice was made on the grounds that it was standard practice not to vaccinate. You should consider whether this is widely used in your own setting.
Validity of estimate of measure of effectiveness
The effectiveness evidence was not derived from a systematic review of published studies: only a recent published trial on PNCRM7 was selected from the literature, whereas the other sources of the data were mainly official reports. Also, the results of the research were not fully reported.
Validity of estimate of measure of benefit
The benefit measure was derived from the effectiveness analysis. It was not used as a summary benefit measure (to be combined with the costs to calculate the cost-effectiveness ratio), but was predominantly considered as an indicator of the resources used to compute the expected total costs. In fact, no data were provided on the mortality.
Validity of estimate of costs
The cost analysis reflected the perspective adopted and included both the direct and indirect costs. This appears to have been relevant to the disease considered. The unit costs were reported separately from the resources consumed. In addition, all the costs were expressed in 1999 prices using the medical care component of the Consumer Price Index. However, statistical analyses were not conducted on either the quantities or the total costs.
The authors compared their finding with those from other studies. The generalisability of the study to other settings was enhanced by the performance of numerous sensitivity analyses. As the authors pointed out, the analysis did not account for any effect of PNCRM7 on the risk of invasive diseases or on mortality among those vaccinated. It also did not take into consideration the possible reduction of the risk of sinusitis, or the emergence of multidrug-resistant bacterial strains. The authors' conclusions were, however, in keeping with the study populations, although the results were presented selectively.
Implications of the study
The authors recommended the wide adoption of routine childhood vaccination against pneumococcal disease in children aged younger than 5 years. However, the limited data, particularly on the effectiveness, restricted the study. This resulted in greater emphasis being placed on the value of the study in terms of the costs.
Source of funding
Supported by Wyeth-Ayerst, Saint Davids (PA), USA.
Weycker D, Richardson E, Oster G. Childhood vaccination against pneumococcal otitis media and pneumonia: an analysis of benefits and costs. American Journal of Managed Care 2000; 6(10 Supplement S): S526-S535
Subject indexing assigned by NLM
Bacterial Vaccines /administration & Child, Preschool; Cohort Studies; Cost Savings; Cost of Illness; Cost-Benefit Analysis; Health Care Costs; Humans; Infant; Otitis Media /economics /prevention & Pneumococcal Infections /economics /prevention & Pneumonia, Bacterial /economics /prevention & Treatment Outcome; control; control; control; dosage /economics
Date bibliographic record published
Date abstract record published