Analytical approach:
The analysis was based on a decision-tree model that included both maternal outcomes (pre-eclampsia, shoulder dystocia, caesarean delivery, and maternal death) and neonatal outcomes (macrosomia, permanent or transient brachial plexus injury, hypoglycaemia, admission to a neonatal intensive care unit, hyperbilirubinaemia, and neonatal death). A lifetime horizon for both mothers and newborns was considered. The authors stated that the analysis was carried out from a societal perspective.
Effectiveness data:
The clinical inputs were from a selection of relevant studies. The rates of maternal and neonatal complications were the key inputs for the model. The treatment effect was from a multicentre randomised controlled trial, which provided most of the clinical inputs.
Monetary benefit and utility valuations:
The utility values were from the literature or, where none were available, conservative assumptions were used.
Measure of benefit:
Quality-adjusted life-years (QALYs) were the summary benefit measure and they were discounted at an annual rate of 3%.
Cost data:
The economic analysis included the costs of treating gestational diabetes (pharmacotherapy, antenatal visits, extra diabetes-related visits, and antepartum foetal surveillance) and the costs of maternal and neonatal complications. These data were from published US sources. All costs were in US dollars ($) and the price year was 2009.
Analysis of uncertainty:
One-way sensitivity analyses were carried out on all the inputs using published ranges of values or ranges defined by the authors. Two-way sensitivity analyses were performed on selected inputs. The efficacy of treatment was introduced and varied in a sensitivity analysis. A Monte Carlo simulation was used to simultaneously vary all the inputs across conventional probability distributions. Cost-effectiveness acceptability curves were generated for a maximum societal willingness to pay (WTP) of $100,000 per QALY gained.