Primum non nocere: stillbirth rate in intrahepatic cholestasis of pregnancy




In reading the article written by Henderson et al, we question the selected background stillbirth rates used to compare to the estimated stillbirth rate in intrahepatic cholestasis of pregnancy (ICP) with expectant management. They found the unexplained stillbirth rate attributed to ICP with expectant management to be 1.2% (4/331) and compared it to published background rates of 1.1% (11/1000) and 0.6% (6/1000). Their analysis of stillbirths in ICP was limited to ones that were otherwise unexplained and >37 completed weeks’ gestation. They excluded stillbirths in pregnancies affected by ICP that were also complicated by congenital anomalies, preeclampsia, abruption, intrauterine growth restriction, or diabetes. However, the authors did not use the same criteria for their control group, which included stillbirths as early as 20 weeks’ gestation and incorporated attributed causes for stillbirth that were excluded in the group with ICP. An appropriate control group would have utilized stillbirth rates that were limited to term stillbirths, which have rates closer to 0.1-0.2% (1-2/1000). This background rate would potentially be lower by approximately 50% if limited to unexplained term stillbirths. Furthermore, we are surprised at the omission of several studies of perinatal outcomes in ICP that appear to meet the inclusion criteria, but are not included in the analysis of stillbirths. Many of the studies that have been included do not use bile acid level in the diagnosis of ICP, are retrospective, and are not adequately powered to robustly assess the frequency of stillbirth in ICP. It is noteworthy that the largest prospective national cohort study of severe ICP (ie, complicated by maternal serum bile acids ≥40 μmol/L) was published a little before the article by Henderson et al, and this did show a significant increase in stillbirth in ICP. In conclusion, although the authors attempt to answer an important clinical question they fail to do so by using inappropriate inclusion criteria for both the ICP and control groups.

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May 6, 2017 | Posted by in GYNECOLOGY | Comments Off on Primum non nocere: stillbirth rate in intrahepatic cholestasis of pregnancy

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