Preterm Birth Clinical Publication Review
Comparison of a novel test for placental alpha macroglobulin-1 with fetal fibronectin and cervical length measurement for the prediction of imminent spontaneous preterm delivery in patients with threatened preterm labor.
Tanja Nikolova, Oleg Bayev, Natasha Nikolova and Gian Carlo Di Renzo
Journal of Perinatal Medicine. 2015
Preterm birth occurs in approximately 6%-10% of pregnancies worldwide with the associated costs in the range of billions of dollars every year. In addition, a single unnecessary admission of a patient suspected of having preterm labour, but who does not actually have the condition adds to these costs.
It therefore follows that an accurate test that that aids in the diagnosis of true preterm labour would provide an excellent negative predictive value (NPV) but should also provide an excellent positive predictive value (PPV).
A recent study by Nikolova, et al. 2015 compares the novel PartoSure (placental alpha macroglobulin-1) test with fetal fibronectin (fFN) and cervical length (CL) measurement for the prediction of imminent spontaneous preterm delivery.
203 consecutively recruited women with singleton pregnancies between 200/7 and 366/7 weeks of gestation with symptoms of preterm labour, clinically intact membranes and cervical dilation of less than 3cm.
The PPV of spontaneous preterm delivery within 7 days in patients with threatened preterm labour for PartoSure, fFN and CL were 76%, 29% and 30% respectively, while the NPV was 96%, 87% and 89% respectively. See Figure One.
While an NPV will tell you how likely it is that a woman won’t go into labour, given the risks associated with preterm birth, the instance of admission, and the possibility of intervention is still high. For women in regional or rural areas, this would involve transfer to a metropolitan hospital with a neonatal intensive care unit (NICU).
A high PPV, gives you the opportunity to intervene where necessary and allow administration of therapeutics to prepare mother and baby for birth.
While fFN and CL have high NPVs (87% and 89% respectively), they have poor PPVs (29% and 30% respectively). PartoSure was found to be statistically superior (p<0.01) for fFN and CL with respect to specificity (SP) and PPV. This provides evidence toward being able to significantly enhance current practice to ultimately reduce the unnecessary administration of potentially harmful therapeutics to patients such as tocolytics, corticosteroids and antibiotics. The use of PartoSure can also reduce the economic burden associated with unnecessary hospital admissions.
In conclusion, PartoSure is the only Time to Delivery test that provides consistently high PPV and NPV results for women between 20 to 37 weeks gestation who have signs, symptoms or complaints suggestive of preterm labour and clinically intact membranes. It is a rapid bedside test that can be performed by doctors, nurses and midwives, with or without speculum examination, giving results in minutes.
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