Study Examines Cost-Effectiveness of Adult Pneumococcal Vaccines

 

 

A computer-based cost-effectiveness analysis suggests that use of the 13-valent pneumococcal conjugate vaccine (PCV13) might prevent more pneumococcal disease compared with the current 23-valent pneumococcal polysaccharide vaccine (PPSV23) vaccination recommendations, while remaining economically reasonable, although the authors note that their findings are sensitive to a number of assumptions, according to a study in the February 22/29 issue of JAMA.1

The PPSV23 vaccine has been recommended for prevention of invasive pneumococcal disease (IPD) in adults since 1983, according to background information in the article. “Most studies show that PPSV23 provides some protection against IPD, but studies have reached contradictory conclusions about its ability to prevent nonbacteremic pneumococcal pneumonia (NPP), which causes several hundred thousand illnesses annually in the United States.” The effectiveness of the PCV13 vaccine in preventing NPP in adults is currently unknown. PCV13 has recently been approved by the Food and Drug Administration for use among adults ages 50 years and older. The cost-effectiveness of PCV13 compared with PPSV23 among U.S. adults is unclear, the authors write.

Kenneth J. Smith, M.D., M.S., of the University of Pittsburgh School of Medicine, and colleagues conducted a study to estimate the effectiveness and cost-effectiveness of pneumococcal vaccination strategies among adults 50 years of age and older. Using various modeling techniques, simulations were performed in hypothetical groups of U.S. 50-year-olds. Vaccination strategies and effectiveness estimates were developed by an expert panel; indirect (herd immunity) effects resulting from childhood PCV13 vaccination were extrapolated based on observed 7-valent pneumococcal conjugate vaccine (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.

With no vaccination, the estimated lifetime risk from age 50 years onward for hospitalized NPP was 9.3 percent, for IPD was 0.86 percent, and for death due to pneumococcal disease was 1.8 percent. Among the different vaccination strategies compared in the analysis, those using PPSV23 were estimated to prevent more IPD than strategies using only PCV13, while strategies using 2 scheduled PCV13 doses were estimated to prevent more NPP.

Regarding cost-effectiveness, in the base case scenario, administration of PCV13 as a substitute for PPSV23 in current recommendations (i.e., vaccination at age 65 years and at younger ages if co-existing illnesses are present) had an estimated cost of $28,900 per quality-adjusted life-year (QALY) gained compared with no vaccination and was more cost-effective than the currently recommended PPSV23 strategy. With routine vaccine administration at ages 50 and 65 years, it was estimated that PCV13 costs $45,100 per QALY compared with PCV13 substituted in current recommendations. Administration of PCV13 at ages 50 and 65 years followed by PPSV23 at age 75 years was estimated to cost $496,000 per QALY gained.

“There are no absolute criteria for cost-effectiveness, but in general, interventions costing less than $20,000 per QALY gained are felt to have strong evidence for adoption, interventions costing $20,000 to $100,000 per QALY have moderate evidence, and those costing more than $100,000 per QALY have weaker evidence for adoption,” the authors write.

The researchers note that 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.

“Model estimates of the effect of adult PCV13 would be strengthened by evidence of PCV13 effectiveness against NPP from ongoing clinical trials and availability of data on the indirect effects of childhood PCV13 on adult pneumococcal disease rates,” the authors conclude.

In an accompanying editorial2, Eugene D. Shapiro, M.D., of the Yale University School of Medicine and Yale Graduate School of Arts and Sciences, New Haven, Conn., writes that policy makers likely will need to decide whether to recommend a change in the strategy for immunization of adults in the absence of definitive data on all values that contribute to analysis of the potential cost-effectiveness of a change in policy.

“The analyses by Smith et al provide a reasonable framework with which to approach this issue. However, if recommendations are made to switch to PCV13 for adults, the degree to which subsequent decreases in rates of both invasive pneumococcal infections and NPP among adults are due to a switch to PCV13 for adults or to the already implemented administration of PCV13 to children might never be known. What does seem clear is that improvements in vaccines against pneumococci and increased rates of immunization likely will result in continued reductions in the incidence of infections due to this common pathogen.”

 

References:

1. (JAMA. 2012;307[8]:804-812.

2. (JAMA. 2012;307[8]:847-848.