Choice of analysis and perspective
A cost-utility analysis using a decision tree was conducted in this economic evaluation. Maternal quality of life, represented by the mean EQ-5D-5L scores in the ANODE trial, was used as a measure of benefit and cost data was recorded in monetary units (£s). The time horizon chosen is 6-weeks, this is because the majority of maternal infections are likely to occur within the first 6-7 days following delivery and resolve within the 6-week time period5. To enable comparison with the NICE ‘cost-effective’ threshold, the outcomes will be expressed as cost per QALY. In calculating the QALYs an assumption will be made that the quality of life (QoL) of patients during the 6-week period is constant and will be scaled to one year.
The choice of perspective used is the UK’s National Health Service (NHS). This is because as a publicly funded healthcare system it has a pressure to deliver cost effective care. Also, the Infection resulting from operative vaginal delivery impacts both primary and secondary care services which are both provided by the NHS and so provides a holistic view of the total economic costs of the intervention.