B. Model input parameters
Resource use: Detailed finance data was only available for the
lead study site, and these data have been used for all participants.
Costs have been estimated inclusive of nursing / midwifery, medical and
allied health staff costs, equipment and consumables, pharmacy,
pathology, radiology, hotel services and business overheads. These have
been calculated as a cost per hour of admission to antenatal ward, birth
suite, theatre, postnatal ward and neonatal nursery. Cervical priming
cost (PGE2 gel, PGE2 tape, cervical ripening balloon) was available at
the patient level, whereas the hourly costs for each inpatient clinical
unit have been calculated by dividing total cost by total clinical
hours. The precise durations of care in each clinical unit was recorded
for all 448 trial participants who were induced.
Health outcomes: Health status was measured using the generic
EQ-5D-3L questionnaire and comprised (a) five domains: mobility,
self-care, usual activities, pain/discomfort and anxiety/depression with
3 response levels each (no problems, some problems and extreme
problems); and (b) a self-reported summary measure of health, using a
visual analogue score (EQVAS), ranging from 0 (worst imaginable health
state) to 100 (perfect health) (17). These health state assessments were
available for 359 women who completed their assessment. The health
utility index ranged from 0 (worst possible health) to 1 (best possible
health) and values represented the utility scores used in the model
according to Australian population norms (18).
Transition probabilities: Transition probabilities between model
pathways were derived by calculations from observed events in the actual
trial data (see Supplementary material, Figure S2). As no deaths were
observed we did not include any risk of mortality associated with either
method of IOL.