Study of progesterone for the prevention of preterm birth in twins (STOPPIT): findings from a trial-based cost-effectiveness analysis.

OBJECTIVES Preterm birth contributes to a range of healthcare problems amongst infants surmounting to sizeable healthcare costs. Twin pregnancies are at particular risk of preterm birth. The objective of this study was to assess the cost-effectiveness of vaginal progesterone gel for the prevention of preterm birth in twin pregnancies. METHODS An economic evaluation was conducted alongside a randomized placebo controlled trial (the STOPPIT trial) of vaginal progesterone gel for the prevention of preterm birth in twin pregnancies. Five hundred women were recruited from nine maternity hospitals in the United Kingdom. The outcomes of the economic evaluation were presented in terms of net benefit statistics, cost-effectiveness acceptability curves, generated using the nonparametric bootstrap method, and the expected value of perfect information. RESULTS Mean health service costs between the period of randomization and discharge for mother and infant were 28,031 pound sterling in the progesterone group and 25,972 pound sterling in the placebo group, generating a mean nonsignificant cost difference of 2,059 pound sterling (bootstrap mean cost difference 2,334 pound sterling; 95 percent confidence interval: -5,023 pound sterling, 9,142 pound sterling; p = .33). The probability of progesterone being cost-effective was 20 percent at a willingness to pay threshold of 30,000 pound sterling per preterm birth prevented. There is little economic justification for conducting further research into the use of vaginal progesterone gel in twin pregnancies for the prevention of preterm birth. CONCLUSIONS Further studies of preventive interventions for preterm birth more generally are required given the scale of the clinical and economic burden of this condition. These studies should be sufficiently powered for economic endpoints and extend beyond hospital discharge.