New test may identify women at risk of preeclampsia but is a long way from market
A new test that analyzes a panel of 14 different chemicals in the bloodstream of pregnant women may eventually become a diagnostic tool for determining whether women are at high risk of developing preeclampsia, researchers said Monday. The research team that developed it said it could be on the market in four to five years, but outside experts predicted that a commercial test would take longer than that, if it can ever be developed.
More than 6 million women around the world and 270,000 in the United States suffer preeclampsia during pregnancy each year. The disorder, once known as toxemia, affects as many as 8% of pregnancies. Usually diagnosed late in pregnancy, the disorder is characterized by sharp increases in blood pressure, swelling and proteins in the urine. It can progress to eclampsia, which produces seizures and often fatal complications of the liver, kidneys, lungs, blood and nervous system. Eclampsia causes 15% of maternal deaths during pregnancy in the U.S. and as many as 75,000 annually worldwide. The cost of treating mothers with the disorder is estimated at about $45 billion annually in the developed world.
Mild cases can be helped by bed rest, but there is no effective treatment for the disorder other than delivery of the infant and removal of the placenta. If the fetus is delivered prematurely, it can develop a wide variety of problems. Premature birth associated with preeclampsia is considered one of the major sources of neurodevelopmental disorders in children. Researchers hope that being able to identify women at high risk of the disorder will allow them to monitor the women more carefully and, perhaps, prevent the most serious effects.
In the new study, a team headed by Dr. Louise C. Kenny of University College Cork in Ireland and Dr. Philip N. Baker of the University of Alberta used a form of highly sensitive liquid chromatography to identify 40 individual chemicals whose levels were higher than normal in the blood of women who were 15 weeks pregnant and who later developed preeclampsia, and an additional five that were lower than normal. From these, the researchers assembled a panel of 14 sugars, fats and amino acids that they thought had the greatest predictive value. The team reported in Hypertension: Journal of the American Heart Assn. that tests in a group of women in New Zealand found that the panel identified 90% of women with preeclampsia. But about 24% of the women identified as having the disorder did not, marking a fairly high false positive rate.
Critics say that tests based on the panel of metabolites are time-consuming, costly and require instruments that are not normally present in a clinical laboratory.
Meanwhile, another test may be closer to widespread use. In 2006, researchers reported that levels of two chemicals, soluble fms-like tyrosine kinase 1 and endoglin are higher than normal in women who go on to develop preeclampsia. The World Health Organization is now completing a trial of the test incorporating the chemicals on more than 8,000 women worldwide and results are expected soon. Roche has already begun marketing a test for the chemicals in Europe and is expected to market it soon in Japan and the United States. Beckman Coulter has also developed a rapid clinical test.
An interesting aspect of those studies is that the chemicals identified are anti-anigiogenic factors, which block chemicals that promote the growth of new blood vessels. Researchers are now attempting to determine whether blocking the activity of the two chemicals might be a way to treat preeclampsia.
Thomas. H. Maugh II / Los Angeles times
