Cost-effectiveness of adult vaccination strategies using pneumococcal conjugate vaccine compared with pneumococcal polysaccharide vaccine

Abstract

Context: The cost-effectiveness of 13-valent pneumococcal conjugate vaccine (PCV13) compared with 23-valent pneumococcal polysaccharide vaccine (PPSV23) among US adults is unclear.

Objective: To estimate the cost-effectiveness of PCV13 vaccination strategies in adults.

Design, setting, and participants: A Markov state-transition model, lifetime time horizon, societal perspective. Simulations were performed in hypothetical cohorts of US 50-year-olds. Vaccination strategies and effectiveness estimates were developed by a Delphi expert panel; indirect (herd immunity) effects resulting from childhood PCV13 vaccination were extrapolated based on observed PCV7 effects. Data sources for model parameters included Centers for Disease Control and Prevention Active Bacterial Core surveillance, National Hospital Discharge Survey and Nationwide Inpatient Sample data, and the National Health Interview Survey.

Main outcome measures: Pneumococcal disease cases prevented and incremental costs per quality-adjusted life-year (QALY) gained.

Results: In the base case scenario, administration of PCV13 as a substitute for PPSV23 in current recommendations (ie, vaccination at age 65 years and at younger ages if comorbidities are present) cost $28,900 per QALY gained compared with no vaccination and was more cost-effective than the currently recommended PPSV23 strategy. Routine PCV13 at ages 50 and 65 years cost $45,100 per QALY compared with PCV13 substituted in current recommendations. Adding PPSV23 at age 75 years to PCV13 at ages 50 and 65 years gained 0.00002 QALYs, costing $496,000 per QALY gained. Results were robust in sensitivity analyses and alternative scenarios, except when low PCV13 effectiveness against nonbacteremic pneumococcal pneumonia was assumed or when greater childhood vaccination indirect effects were modeled. In these cases, PPSV23 as currently recommended was favored.

Conclusion: Overall, PCV13 vaccination was favored compared with PPSV23, but the analysis was sensitive to assumptions about PCV13 effectiveness against nonbacteremic pneumococcal pneumonia and the magnitude of potential indirect effects from childhood PCV13 on pneumococcal serotype distribution.

Figure 1. Schematic depiction of the Markov model for pneumococcal vaccination and infection

Model health states are shown as ovals. During yearly model cycles, transitions between health states or remaining in the same health state can occur, represented by the arrows. Transitions to pneumococcal disease states are based on vaccination effects and herd immunity projections.

Figure 2. Markov cycle tree

The cycle tree gives more detail on the programming of the Markov model. Health states are the first branches off the Markov node. Pneumococcal diseases (invasive pneumococcal disease, IPD and nonbacteremic pneumococcal pneumonia, NPP) are modeled as virtual states (“tolls”) within the tree structure. The triangular terminal nodes (on the left) depict the health states where portions of the cohort following that path will begin the next yearly cycle of the model.

Figure 3. Probabilistic sensitivity analysis for adult pneumococcal vaccination strategies

Results are shown as a cost-effectiveness acceptability curve. The y-axis shows the likelihood that strategies would be considered cost-effective for a given cost-effectiveness willingness to pay (or acceptability) threshold.

Figure 4. Cost-effectiveness acceptability frontier

The cost-effectiveness acceptability frontier depicts the strategy with the highest expected net benefit for a given willingness to pay threshold. The no vaccination strategy has the highest expected net benefit at values of ≤$35,000/QALY, PCV13 substituted for PPSV23 in current recommendations is favored from $40,000-50,000/QALY, and PCV13 at ages 50 and 65 is favored at higher willingness to pay thresholds >$50,000/QALY.