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Vaccines for the 21st Century: A Tool for Decisionmaking
pected to be available more quickly and cheaply. In general, the committee found that the adjustments for efficacy and utilization had a more substantial impact on a vaccine’s cost-effectiveness than the additional time and cost needed for development. Although these adjustments changed the cost-effectiveness ratios, only a few vaccines shifted in their cost-effectiveness relative to the other vaccines.
For each of the conditions included in the study, multiple sensitivity analyses could be performed to test alternative assumptions regarding the morbidity scenarios, the quality-adjustment weights, the costs of care and vaccine development, utilization rates, and numerous other factors. Because 26 conditions were considered, however, the committee was not able to undertake a detailed case-by-case approach to sensitivity analysis. As an alternative, a series of hypothetical cases for vaccine x were developed to illustrate the effects that changes in various factors (e.g., numbers of cases, age distribution of patients, severity of illness, unit costs of care, and so on) would produce in the cost-effectiveness ratio.
The committee chose to perform sensitivity analyses for vaccine x with limited set of factors of significance across all conditions. One of these analyses addressed the debate within the committee and in the cost-effectiveness literature over the appropriateness of discounting future health benefits. The basic analysis used a 3% discount rate for both health benefits and costs. Two sensitivity analyses were performed: (1) the discount rate for health benefits was set at zero, whereas the rate for costs was maintained at 3% and (2) the discount rate was set at zero for both health benefits and costs. The results of these analyses are discussed later in this chapter.
Exclusions from the Analysis
Several factors excluded from the committee’s analysis are reviewed briefly. In theory, the analysis should also consider the impact of vaccine use on the time costs borne by patients in obtaining treatment or vaccination for any of the conditions studied and by parents, spouses, or other unpaid caregivers who provide care to individuals who experience any of these conditions. For some conditions, these costs could be substantial. For example, an analysis of the cost-effectiveness of a varicella vaccination program estimated an annual savings of $325 million (discounted 1990 dollars) in parents’ time lost from work (Lieu et al., 1994).
The committee felt, however, that it lacked adequate information to make a consistent assessment across the various conditions of the time involved in obtaining treatment or of the extent of care from unpaid caregivers. It is readily apparent that sick children will require care from parents or other adult caregivers, but it is less clear whether adults who are ill routinely receive similar unpaid care from others and, if they do, how much care they receive. Therefore, the committee chose not to include these costs in its analysis. If suitable time cost