Saving Costs from Influenza Immunization Among

Saving Costs from Influenza Immunization Among Young Children — Economic Benefits of Using Live Attenuated vs. Inactivated Influenza Vaccination to Payers

Objective:

To evaluate the relative costs and benefits, from a payer perspective, between LAIV and TIV for healthy children 24–59 months of age. Methods:

We conducted a payer perspective, cost consequence analysis of LAIV compared to TIV, using patient-level data from the head-to-head RCT (2004–2005 season) supplemented with cost data from published literature and health claims analysis. Model outcomes included total direct costs to payers and cases of influenza avoided for a single influenza season. Vaccine related cost including average payer reimbursement for vaccine, its administration, and related adverse events. Costs related to breakthrough cases of influenza were also considered (outpatient visits, ER visits, hospitalization, and medication usage). The vaccine dosage and percentage of children receiving two doses (69.4%) were assumed to be the same as seen in the RCT. All costs were reported in 2008 US dollars. Sensitivity analyses (SA) were run to capture the uncertainty of the model variables. Results:

Due to higher estimated efficacy among young children (based on data from a RCT), LAIV had lower total direct costs per child ($83.75) compared to TIV ($92.00). Based on this model, use of LAIV is estimated to result in a cost savings of $8.26 per vaccinated child (95% CI: $3.09–$13.39 savings). For every 100,000 children vaccinated, there were an estimated 4893 influenza cases among LAIV recipients vs., 10,464 influenza cases for TIV recipients. The estimated 5,571 fewer cases of influenza among children receiving LAIV lowered overall healthcare utilization and resulted in a net cost savings despite LAIV’s higher per dose cost. The SA found that the difference in vaccine acquisition and administration prices, difference in vaccine efficacy, the proportion of children receiving two doses, and costs of hospitalization for influenza were influential parameters in the model. Conclusions:

The payer specific analysis shows that compared to vaccinating with TIV, LAIV can save costs and prevent influenza cases in children aged 24 to 59 months.

Objective ♦♦ To analyze the cost-effectiveness of LAIV relative to TIV in preventing influenza in children aged 24–59 months based on the results of the Comparative Efficacy Study.

Introduction ♦♦ Seasonal influenza epidemics are estimated to cause 200,000 hospitalizations and 36,000 excess respiratory deaths annually in the US.1–3 While most of the influenza related morbidity and mortality occurs in the elderly, young children are hospitalized for influenza-attributable illnesses at rates similar to the elderly,2, 4, 5 and influenza attack rates are highest among children — as high as 33.8%.6 ♦♦ The US Advisory Committee on Immunization Practices (ACIP) recommended influenza immunization for children 24–59 months of age because of the increased risk for influenza-associated clinic and emergency department visits in this age-cohort.7 ♦♦ Currently, two influenza vaccines are available in the U.S: (1) live attenuated influenza vaccine, trivalent (LAIV) and (2) inactivated influenza vaccine, trivalent (TIV). These have been compared in three head-to-head pediatric clinical trials. LAIV has been shown to significantly lower rates of culture-confirmed influenza illness as compared with TIV.8–10 LAIV is not approved for use outside of the United States. ♦♦ Due to a large sample size of children in a population indicated for both vaccines, the 24–59 month cohort from the Comparative Efficacy Study informed this cost-effectiveness analysis.10

Model Inputs

♦♦ Data for children aged 24–59 months in the Comparative Efficacy Study were used to populate model pathways, clinical outcomes, and resource use parameters. Supplemental data for parameters that could not be obtained from the trial were collected from the published literature. ♦♦ No influenza mortality was observed in the Comparative Efficacy Study; however, it is a relevant outcome. The present model incorporated expected rates of mortality due to influenza based on estimates reported in the published literature for uncomplicated and complicated influenza among children aged 24–59 months. (Table 1) ♦♦ Medically significant wheezing (MSW) is the only vaccine-related adverse event included in the model because it would require additional treatment covered by the third party payer. ♦♦ Costs were categorized as vaccination costs (i.e., vaccine acquisition, administration, and adverse event costs) and influenza direct costs (i.e., influenza-related hospitalizations, ER visits, and office visits). Model Assumptions Dosing Administration

♦♦ The vaccine dosage and percentage of children receiving two doses is assumed to be the same as the Comparative Efficacy Study (69.4%).10

♦♦ For every 100,000 children vaccinated, use of LAIV was projected to save approximately $826,000 in direct health care costs compared with the use of TIV. ♦♦ In 5571 cases of influenza (4346 uncomplicated and 1,225 complicated influenza), 138 hospitalizations, 250 ER visits, and 7058 outpatients physician visits were avoided for every 100,000 children vaccinated with LAIV relative to TIV. An estimated 36 QALYs were gained for every 100,000 children vaccinated with LAIV instead of TIV (Table 4). ♦♦ The incremental cost per QALY gained was not calculated in this case because LAIV resulted in lower costs and increased QALYs compared to TIV. Table 5 displays comparisons between the two vaccines. Sensitivity Analyses

♦♦ Figure 2 depicts one-way sensitivity analysis for key variables. LAIV was cost-saving relative to TIV in each analysis. The model was most sensitive to vaccine administration price and acquisition price differentials, relative risk reduction for LAIV compared with TIV and the percentage of patients receiving two doses. ♦♦ The results of the probabilistic sensitivity analysis are presented as a scatter plot in Figure 2 and indicate that LAIV was associated with both increased QALYs and lower costs relative to TIV in 100% of the simulations.

Figure 3. Scatter Plot

Input

♦♦ Influenza was defined as fever ≥ 100°F oral or equivalent plus the presence of cough, sore throat, or runny nose/nasal congestion on the same or consecutive days per the Centers for Disease Control and Prevention.10 Complicated influenza was defined as any case of influenza that was accompanied with documented AOM and/or LRI within 7 days before or 14 days after the onset of influenza symptoms. ♦♦ AOM was defined as a health care provider diagnosis concurrent with fever and treatment with antibiotics. AOM is not associated with an increased risk of mortality. ♦♦ LRI was defined as healthcare provider-confirmed shortness of breath, pulmonary congestion, pneumonia, bronchiolitis, bronchitis, wheezing, or croup. ♦♦ MSW was defined as the presence of wheezing on physical examination and accompanied by at least one of the following: 1) sign of respiratory distress: tachypnea, retractions, or dyspnea; 2) hypoxemia (O2 saturation