Tocolysis in preterm labour - A systematic review of evidence-based guidelines, effectiveness and health economic evaluations

Premature birth before the end of the 37th week of gestation is associated with an increased risk of morbidity and mortality in newborns. Using drugs to suppress labour (tocolysis) does not prevent the causes of imminent premature birth, in most cases the birth can merely be temporarily delayed. In Austria, the drugs used in tocolysis are the betamimetic Hexoprenalin, a low cost drug which often leads to cardiovascular side effects, and the oxytocin receptor blocker Atosiban, which has fewer side effects but is more costly. The aims of the systematic review were to summarise (1) existing evidence-based guidelines for the treatment of imminent premature birth, (2) existing studies on the effectiveness and safety of tocolysis and, (3) health economic evaluations of the tocolysis drugs currently authorised in Austria. Evidence-based guidelines for tocolysis make the following recommendations: - Tocolysis is only indicated before the end of the 34th week of pregnancy. - In routine practice only one cycle of tocolysis should be carried out in a 48 hour period. Neither a repetition of the treatment nor maintenance therapy are recommended. Using a combination of several tocolysis drugs is also not recommended. - When tocolysis is required, corticosteroids should be administered to help lung maturation, and, if necessary, the patient should be transferred to a neonatological centre. - Contraindications for tocolysis are increasing intrauterine infections, and fetuses that are unviable due to malformations. - Accompanying measures such as strict bed rest, hydration or sedation are not recommended in routine practice. Betamimetics were effective in delaying birth by 2 to 7 days compared to placebo. However, they did not change neonatal mortality and morbidity. No significant differences in effectiveness and safety were found between the different betamimetics. Under study conditions, Atosiban and betamimetics demonstrated the same effectiveness in terms of prolonging pregnancy, but Atosiban had fewer side effects. In order to avoid a side effect associated with betamimetic treatment, 6 women need to be tocolysed using Atosiban (NNT =6). Atosiban failed to reduce morbidity and mortality to a greater extent than placebo or betamimetics. No health economic evaluations of Hexoprenalin, and just one of Atosiban could be identified, therefore a statement as to the cost-effectiveness of Hexoprenalin compared with Atosiban is currently not possible. Due to study heterogeneity in terms of design, intervention and data used, the cost-effectiveness of the tocolytics used in the studies cannot be assessed.