Reduces the itching but not by much.

Our factorial trial of ursodeoxycholic acid (UDCA) and/or early delivery as treatments for obstetric cholestasis (OC) has just been published in the BMJ. Here’s the link to the full article. Here‘s the one page summary. It’s open access, so free to readers*, but if there’s a problem here’s a copy of the pdf.  PITCH trial BMJ.

Although the largest trial yet, it was nowhere near big enough to measure the effect of UDCA on baby outcomes with any precision. So before we unblinded the drug arms we did two things. First we agreed on a primary outcome, the average of all itching scores measured between randomisation and delivery. Second we surveyed expert obstetricians, and women identified via the OC support group, and asked them:

“If your [patient’s] itching score was 60 out of 100, (where 0 = no itching and 100 = worst possible/intolerable) how much of an improvement would make it worth your while to take an unlicensed and, as regards fetal safety, unproven but widely used drug every day?”

To help them we suggested that they obviously would not bother to take the drug if it reduced the score by only one point down to 59, but they probably would if it reduced it by 60 points down to zero. We wanted them to tell us the threshold that would make taking UDCA worth the inconvenience.

Individual responses varied but the average for patients and doctors was the same.  They would take the drug if it reduced the score by 30 points or more.

And the true effect?  UDCA reduced the itching score by only -16 points with a 95% confidence interval of -27 to -6.

In summary it works, but not much.  The size of the effect is so small that most women and doctors would judge the benefit as hardly worth the hassle and the risks.

Next project. Repeat the trial in 2,000 women to measure the effect on the baby.

Better hurry. In the UK alone nearly 5,000 women get given UDCA every year outside trials and no-one knows if it does more good than harm.

Jim Thornton

*Nottingham university paid a compulsory authors fee to the BMJ to make the article open access, and the government gives Nottingham a research subsidy to cover these fees. I.e. you, the taxpayer, paid to read my article whether you wanted to or not!