The costs of induction of labour by prostaglandin E2 or oxytocin: refining the estimates

Approximately 17.5% of all pregnancies in England are induced. Induction of labour may be required for several reasons. These include hypertension, intra-uterine growth retardation, diabetes, poor weight profile of the mother and prolonged pregnancy. The two principle methods used to induce labour are artificial rupture of the membrane (ARM) with or without oxytocin and prostaglandin E2 (PGE2). Both methods have been shown to be effective. However, there are substantial differences in the acquisition costs of the drugs. The cost of oxytocin is approximately 18 pence per 5 units compared to £21 for PGE2. However, there are likely to be differences in the costs of other health care services associated with induction of labour. This means that it is important to examine the broader costs and consequences of these two methods of induction, particularly as it is a frequently applied procedure with large resource consequences. A preliminary economic evaluation of PGE2 compared with oxytocin and ARM found that, when the broader costs and consequences were considered, PGE2 for woman with an unripe cervix was cost neutral or cost saving under many assumptions. In the case of women with a ripe cervix, savings in the use of health care resources would only partially offset the additional cost of PGE2. Due to a lack of data, the earlier analysis was based on a number of assumptions about the level of health care resources used in the management of labour and complications associated with childbirth, and limited clinical data of effectiveness. The results of the analysis were shown to be sensitive to changes in the assumptions made about resource use and the probability values used. When economic evaluation results are sensitive to key assumptions or data, the appropriate response is to attempt to collect better data where feasible. Health care purchasing decisions need to be based on reliable and up-to-date information. The objective of this paper is to refine the earlier estimates and also to assess the reliability of the previous study. In the primary analysis for this study, the expected net saving of PGE2 was £50 for women with an unripe cervix. This was slightly lower than the expected net saving for women with a ripe cervix in this study was £5 compared to an expected net cost of £17 in the first analysis. Overall, the conclusions of this analysis confirm those of the previous evaluation for women with an unripe cervix, but not for women with a ripe cervix. Given the growing importance being attached to economic evaluation results in health care decision making, consideration should more often be given to refining the estimates of earlier evaluations as new data becomes available.