Challenges in identifying high risk patients for preeclampsia using USPSTF guidelines

Thomas McElrath, MD, PhD, of the Department of Obstetrics & Gynecology at Brigham & Women’s Hospital, is the lead and corresponding author of a paper published in JAMA Network Open, "Utility of the US Preventive Services Task Force for Preeclampsia Risk Assessment and Aspirin Prophylaxis."

Q: How would you summarize your study for a lay audience?

Dr. McElrath: Preeclampsia (PE) is a hypertensive disease that complicates 7-10% of pregnancies. While recent advances in understanding the underlying causes of PE have been made, predicting its occurrence has historically been difficult because it is a complex condition that likely results from a variety of causes and can present in different ways.

To address this challenge, the United States Preventive Services Task Force (USPSTF) reviewed a series of PE-associated studies to develop a set of risk factors to assist in characterizing patient risk of PE. However, since these risk factors were identified in individual and separate studies, they have not been evaluated as a whole to see how effective they are at stratifying risk within a single, diverse patient population.

We aimed to assess how well these guidelines help physicians identify patients at risk of PE and if those patients who were identified as being at-risk patients were directed to take aspirin as a preventative measure.

We found that using the USPSTF guidelines identified 89% of participants as being at either moderate or high risk for PE. With the vast majority of the population being labeled as "at risk," it is unclear if the USPSTF guidelines are serving their intended use of helping clinicians identify patients at most need of additional care.

Furthermore, we found that only 37% of the participants who were identified as being at moderate risk were receiving the recommended prophylaxis of one low-dose aspirin per day, suggesting a gap still exists between risk identification and connection to preventative care.

Q: What question were you investigating?

How well do the risk assessment guidelines for preeclampsia that were developed by the USPTF work in identifying those at increased risk of preeclampsia?

Subsequently, how many of those individuals identified at increased risk are receiving a prescription of aspirin prophylaxis, as recommended by the American College of Obstetricians and Gynecologists and the Society of Maternal-Fetal Medicine?

Q: What methods or approach did you use?

We approached and enrolled 5,600+ individuals with singleton pregnancies who met the inclusion criteria for the study at 11 different centers in geographically diverse area of the United States.

For the purposes of the study, we defined individuals as being in the high-risk category if they had at least one high risk factor (as identified by the USPTF). Individuals were defined as being in the moderate risk category if they had at least one of the moderate risk factors, but no high-risk factors. Participants were defined as being in the low-risk category if they had no moderate or high-risk factors.

Q: What did you find?

Using the USPTF screening guidelines, we found that 18% of participants were in the high-risk category, 71% of participants were in the moderate risk category and 11% were in the low-risk category.

These categories were therefore labeling 89% of the population as at moderate or high risk for PE.

With the majority of the population being labeled as risk, it is unclear if the USPSTF guidelines are serving their intended use of assisting clinicians in stratifying preeclampsia risk.

The actual rates of PE for each of the three categories were as follows:

• 0% for those identified as low risk
• 5% for those at moderate risk
• 5% for those at high risk

While the majority of patients (82%) at high risk for PE received a recommendation for aspirin prophylaxis, patients at moderate risk for PE received recommendations at much lower rates.

Only about half of the patients with two or more moderate risk factors received recommendations for an aspirin prophylaxis while less than 25% of patients with one risk factor received a recommendation for aspirin.

Q: What are the implications?

If the intended utility of the guidelines is to facilitate the focus of clinical attention and limited clinical resources on those at greatest risk of preeclampsia, identifying the majority of the population as "at risk" does not meet this end.

Q: What are the next steps?

The risk factors for PE, and probably other conditions, should be simultaneously evaluated in a single population, not just compiled from the results of separate and individual studies, to ensure that they provide clinically actionable information that can assist with patient risk stratification and the alignment of clinical resources.