- Soluble Fms-like Tyrosine Kinase Associated with Preeclampsia in Pregnancy in Systemic Lupus Erythematosus
Journal of Rheumatology, Volume 35, Number 4, April 2008, pp. 631-634
What is the topic?
Preeclampsia is a condition that may occur during pregnancy, with a four-fold increased risk in lupus patients. It is characterized by high blood pressure and large losses of protein in the urine. This is dangerous for both the mother and the baby. There is no good way to stop preeclampsia other than delivering the baby as soon as possible, and no guaranteed way to prevent it, so women at high risk have to be monitored closely in the last trimester of pregnancy. Risk factors for preeclampsia include prior kidney disease and chronic hypertension.
What did the researchers hope to learn?
A number of studies have pointed to a possible role for a protein called Fms-like tyrosine kinase (sFlt-1) in the development of preeclampsia. sFlt-1 is produced in the placenta. In this study, the researchers wanted to see if there was any relationship between the levels of sFlt-1 and preeclampsia in pregnant women with lupus.
Who was studied?
The researchers studied 52 pregnant women with lupus who were being followed as part of the Hopkins Lupus Cohort, a long-term study at the Johns Hopkins University Medical Center in Baltimore. Their pregnancies all occurred between 1999 and 2001. Forty percent (40%) of the women were African American, 58% were Caucasian, and 1% were Asian. Preeclampsia was present in 18 of the 52 pregnancies (35%).
How was the study conducted?
The researchers examined the levels of sFlt-1 in stored blood samples that had been taken from the women at 4-6 week intervals between the 22nd and 32nd weeks of their pregnancy. The researchers also had access to other demographic and clinical data from the patients that could be used to determine if other risk factors could have contributed to the preeclampsia. They compared the levels of sFlt-1 of the women who developed preeclampsia and those who did not.
What did the researchers find?
The researchers found that the levels of sFlt-1 were significantly higher in the women who were identified as having preeclampsia than among the other pregnant lupus patients. The difference in sFlt-1 levels was evident in blood samples taken as early as the 25th week of the pregnancies, which is earlier than preeclampsia is usually diagnosed. However, there was no correlation between the levels of sFlt-1 and lupus disease activity. On average, the women with preeclampsia in the study delivered their babies earlier in their pregnancy (35.97 weeks versus 38.14), and their babies weighed less (5 lbs, 12 oz. vs. 6 lbs, 14.5 oz.). The researchers concluded that elevated levels of sFlt-1 could be a predictor for preeclampsia among women with lupus who are pregnant.
What were the limitations of the study?
The researchers only obtained data on 52 pregnant women, and further studies following many more women will be needed to substantiate the association they observed between sFlt-1 and preeclampsia. Also, although the researchers did indicate that 17% of the patients in the study were taking hydroxychloroquine and 33% were on prednisone, they did not show whether those medications made a difference in the outcomes. Also unknown was whether other important distinctions among lupus patients -- for example, how long they had been diagnosed and at what age, what symptoms they had, or what organ system was involved -- might have had some impact on the course of their pregnancies. All of these factors might have influenced the level of the protein being studied and could have had a potential impact on the results of this study.
What do the results mean for you?
In the not-too-distant past, pregnancy was a difficult decision for women with lupus, but the risks have become more controllable as management of high-risk pregnancies has become more routine. However, preeclampsia still remains a serious concern for lupus patients. If ways can be found to identify women who are more likely to develop preeclampsia -- while this research suggests increased levels of sFlt-1, there may be others -- then at-risk women can be referred earlier for management and monitoring by specialists in high-risk obstetric care, and perhaps other women with lupus could be reassured that their pregnancy risks are smaller.