Fig. 2

Incremental cost-effectiveness of the QUARISMA intervention versus routine care, by risk subgroups. Cost-effectiveness (CE) planes for the covariate-adjusted cost-effectiveness analysis of the QUARISMA intervention versus routine care, by patient risk subgroups. Incremental cost-effectiveness results were based on 20,000 Markov chain Monte Carlo iterations estimated separately for low risk (N = 49,281) and high-risk (N = 56,070) trial participants. An ellipse containing 95% of the joint posterior distribution of incremental costs and effects is used to represent uncertainty on the CE plane. The centre of the ellipse represents the point estimate of incremental effects and costs, i.e. a per-patient reduction of 0.014 caesarean sections and $226 saved for the low-risk subgroup, and a per-patient increase of 0.008 caesarean sections and $75 expenditure for the high-risk subgroup. Percentages represent the distribution of points by quadrant; figures may not sum to 100 due to rounding