Network meta-analysis of multiple outcomes to inform a cost-effectiveness analysis: interventions for the induction of labour

Tags: Oral
Keeney E1, Alfirevic Z2, Dowswell T2, Welton NJ1, Medley N2, Dias S1, Jones LV2, Gyte G2, Caldwell DM1
1University of Bristol, United Kingdom, 2University of Liverpool and Liverpool Women's Hospital, United Kingdom

Background: Network meta-analysis (NMA) allows estimation of multiple intervention effects across a network of interventions. NMA is particularly useful for economic evaluations, which compare the cost-effectiveness of multiple interventions. However, economic evaluations usually depend on several outcomes, whereas a systematic review typically reports one outcome at a time.

Objectives: Our aim is to illustrate the joint modelling of multiple outcomes, and assessment of inconsistency in NMA, for providing inputs to an economic model.

Methods: We use as an example a systematic review and NMA to identify the most cost-effective intervention(s) for induction of labour. Trials in this area report multiple, but related, outcomes for the mother and baby. The economic model requires estimates of the probabilities of vaginal delivery (VD) within 24 hours, VD after 24 hours, and caesarean section, as well as the proportion of babies admitted to intensive care. These outcomes are not independent, and require estimating jointly in the NMA. Careful definition of denominators allows estimates of conditional probabilities for inputs for the economic model to be obtained. We use various approaches to explore and deal with inconsistency in the NMA, including node-splitting, continuity correction and removing trials at high risk of bias.

Results: Titrated (low-dose) oral misoprostol solution is the treatment that not only has the lowest cost but also results in the highest utility for mothers and babies.

Conclusions: Related outcomes should be jointly modelled in order to provide the required estimates for economic models. We found that trials did not always provide enough information to be able to identify the outcomes needed in the economic model. Exploring and dealing with inconsistency is essential for the validity of conclusions drawn from an economic evaluation based on a NMA.