Last year, the Advisory Committee on Immunization Practices made a recommendation to vaccinate adults aged 50 years and older with the new recombinant adjuvanted zoster subunit vaccine, Shingrix, over the only other FDA-approved vaccine, Zostavax. The committee also recommended that adults previously vaccinated with Zostavax receive an immediate booster with Shingrix. New data, however, show it would be more cost-effective to begin vaccinating adults at 55 years of age and offer the booster after 5 years of Zostavax vaccination.
“The recommendations by the ACIP was informed by the CDC model, which assumed a high probability of postherpetic neuralgia and 100% adherence,” Phuc Le, PhD, MPH, and Michael B. Rothberg, MD, MPH, both from the Center for Value-Based Care Research at Cleveland Clinic, wrote in JAMA Internal Medicine. “In this modeling study, we found that neither ACIP recommendation would be cost-effective, unless adherence to the two-dose regimen approached 100%.”
According to the researchers, it is unlikely that all patients will be 100% adherent to the two-dose Shingrix (GlaxoSmithKline) schedule because of the high costs of the full series, which is approximately $280. Additional barriers to compliance include the need for a second office visit, potential reimbursement issues and concerns with severe local reaction after the first dose, which occurs in an estimated 6% of patients.
For their study, Le and Rothberg calculated the incremental cost-effectiveness ratio (ICER) of Shingrix based on willingness-to-pay thresholds of $50,000 per quality-adjusted life-years (QALYs) and $100,000 per QALYs. They compared ICERs when adherence rates to the two-dose vaccine schedule were assumed to 100% and “a more realistic estimate” of 56%.
In a probabilistic sensitivity analysis, vaccination at 50 years of age had a 23% chance of being cost-effective. The model showed that higher adherence to the full schedule increased cost-effectiveness at younger ages. The ICER was estimated to be $151,430 per QUALY at 50 years of age, declining to less than $100,000 per QALY at 53.2 years of age and less than $50,000 per QALY at 57.1 years of age.
When assessing the cost-effectiveness of the booster dose, the researchers reported that immediate revaccination was only reasonably cost-effective when adherence was 100%. When adherence was assumed to be 56%, the booster had a 9% chance of being cost-effective when given immediately and a 75% chance when given after 5 years of initial vaccination.
“Given our best estimates, vaccination with [Shingrix] at 55 years of age and a booster at least 5 years after [Zostavax (Merck) vaccination] would offer better value,” the researchers concluded. “Clinicians may consider vaccination earlier for patients who are very likely to comply with a second dose,” they wrote. “In all cases, efforts should be made to enhance compliance with the full series,” they wrote. – by Stephanie Viguers
Disclosures: The researchers report no relevant financial disclosures.