Pharmacists as Advocators for Influenza Vaccination in Elderly Patients: A Cost-Effectiveness Analysis

OBJECTIVES: Influenza incurs a significant worldwide disease burden, and influenza vaccination is an effective preventive intervention. In Hong Kong, the influenza vaccine uptake rate in adults aged ≥65 years ranged between 40% to 51%, lower than the target vaccination rate (75%) recommended by the European Council of Ministers. Clinical findings reported that pharmacists as advocators improved the influenza vaccination uptake. This study aimed to examine the cost-effectiveness of pharmacists as advocators to improve influenza vaccination coverage among the elderly population from the perspective of public healthcare provider in Hong Kong.

METHODS: A decision analytical model was designed to evaluate clinical and economic outcomes of pharmacists as advocators versus usual care for influenza vaccination in elderly patients aged ≥65 years. The model timeframe was 1 year. Model inputs were obtained from published literature and public data. Primary outcomes were direct medical costs, quality-adjusted life-years (QALYs) loss, and incremental cost per QALY saved (ICER). Base-case analysis and sensitivity analyses were performed.

RESULTS: In the base-case analysis, the pharmacists as advocators strategy increased cost by HKD61 (USD 1=HKD 7.8) and saved 0.0002 QALY when compared to usual care. The ICER was HKD303,245 per QALY gained, lower than willingness-to-pay threshold of HKD1,109,799 (3× GDP per capita in Hong Kong). In one-way sensitivity analysis, the advocator strategy remained to be cost-effective if the influenza infection rate was >4%. In probabilistic sensitivity analysis, QALYs saved and incremental cost by the advocator strategy were 0.000195 (95% CI: 0.000193 – 0.000196; p <0.01) and HKD67.7 (95%CI: 67.3 – 68.3; p <0.01), respectively. The advocator group was cost-effective in 99.2% of 10,000 Monte Carlo simulations.

CONCLUSIONS: Pharmacists as advocators for influenza vaccination appeared to have a high probability to be accepted as a cost-effective strategy in the elderly population, subject to the influenza infection rate in Hong Kong.