Analytical approach:
The analysis was based on a decision tree model with a one-year time horizon. The perspective was that of the health system payer.
Effectiveness data:
Clinical inputs for non-vaccinated women were derived from an administrative database in Nova Scotia of 134,188 pregnant women over the period 1990 to 2003. A randomised controlled trial was used to estimate the efficacy of vaccination on pregnant women. The main endpoints were event rates defined as the number of physician visits or hospital admissions for an influenza-related diagnosis.
Monetary benefit and utility valuations:
Utility valuations were based on published sources supplemented with an authors’ assumption regarding the quality of life associated with the Guillain-Barré syndrome.
Measure of benefit:
Quality-adjusted life-years (QALYs) were used as the summary benefit measure.
Cost data:
The economic analysis included costs of vaccination, family practitioner delivery, influenza-related physician utilisation, hospital services and treatment of Guillain-Barré syndrome. These costs were derived from official sources such as Nova Scotia Department of Health and Wellness, Nova Scotia physician utilisation database and Ontario Case Cost Initiative database. The annual cost of Guillain-Barré syndrome was taken from a USA study. Costs were in Canadian dollars ($). The price year was 2010.
Analysis of uncertainty:
An alternative scenario considered the vaccination strategies being delivered in a public health clinic or delivered with an additional family practitioner visit. One-way sensitivity analyses and threshold analyses were carried out on selected inputs using published and assumed ranges of values.