Universal Screening of Pregnant Women May Lead to Fewer Adverse Outcomes for Mother and Child

Deborah Brauser

October 02, 2009

October 2, 2009 (Palm Beach, Florida) — Treating thyroid hormone abnormalities during the first trimester of pregnancy can lead to a significant decrease in adverse outcomes for both the mother and her infant, according to a large randomized study presented here at the American Thyroid Association (ATA) 80th Annual Meeting.

In addition, the investigators found that using a strategy of universal screening (US) and treating pregnant women deemed "low risk" for thyroid disease led to fewer adverse outcomes than case finding (CF).

Dr. Alex Stagnaro-Green

The results were reported during an oral presentation by Alex Stagnaro-Green, MD, from the Department of Medicine, Obstetrics and Gynecology at Touro University College of Medicine in Hackensack, New Jersey.

In this study, the investigators sought to "determine if treatment of thyroid disease during pregnancy decreases the incidence of adverse outcomes, and to compare the impact of [US and CF]," said Dr. Stagnaro-Green.

A total of 4516 pregnant women in their first trimester were enrolled from 2 ambulatory clinics in Southern Italy (an area considered to have a prevalence of mild iodine deficiency) and were randomly assigned to either the US group (n = 2257) or the CF group (n = 2259).

All the patients were then stratified, on the basis of specific risk factors, as either high risk (US, n = 475; CF, n = 451) or low risk (US, n = 1782; CF, n = 1808) for thyroid disease.

All patients in both US groups and in the high-risk CF group were then tested for free T4 (fT4), thyroid-stimulating hormone (TSH), and the thyroid peroxidase antibody (TPO-Ab). Those with a TSH above 2.5 mIU/L who were TPO-Ab positive were treated with levothyroxine, and those with a suppressed TSH and an elevated fT4 received antithyroid medication.

The women in the low-risk CF group were not tested or treated until after they had given birth.

"The primary outcome measure was the total number of adverse outcomes during pregnancy or in the immediate neonatal period for the mother or fetus," explained Dr. Stagnaro-Green.

Adverse Outcomes Less in US Than in CF

Results at the end of the study showed that when using a mixed logistic regression model, which controlled for clustering, the adverse outcomes were significantly less likely to occur in the low-risk US group than in the low-risk CF group (odds ratio, 0.48; 95% confidence interval, 0.33 - 0.71.)

After 51 of the low-risk US women who met the criteria for hypo- or hyperthyroidism were treated, 38% of them experienced 1 or more adverse outcomes.

In the low-risk CF group (women who were not treated during pregnancy), 39 met the criteria for thyroid disease postpartum. Of those, 92% had 1 or more adverse outcomes.

The number needed to screen to detect 1 case of hypo- or hyperthyroidism in the low-risk group was 36 (range, 28–49), and the number needed to treat to prevent 1 woman from experiencing an adverse outcome was 1.8 (range, 1.4–2.6).

In addition, on the basis of mixed model results, the screening of low-risk women was associated with 2.48% fewer adverse outcomes than otherwise expected (= .012).

Cost Analysis Needed

"By identifying and treating women with thyroid disease, we were able to show that you can decrease adverse outcomes to the mom or to the fetus," said Dr. Stagnaro-Green.

He added that "all high-risk women should be screened for thyroid disease and serious consideration should be given to universal screening. What is needed now is a cost–benefit analysis to determine the benefit of screening and treating low-risk women to decrease the number of adverse neonatal complications."

When asked during the Q&A session at the end of the presentation why the recommendations weren't stronger, Dr. Stagnaro-Green replied: "My gut tells me that we should recommend universal screening for all pregnant women, which is another 80% of that population. But I don't think society at large and the obstetrical community, etc., are going to accept this until we show the cost–benefit analysis."

He added that his team is currently in the midst of doing just that and they hope to present the results at the International Thyroid Congress in Paris in September 2010.

"Clearly, [this study] pushes us very strongly to move forward for universal screening," he concluded.

Important Implications

Calling the study "meticulously done and methodologically sound", session moderator Julie Ann Sosa, MD, associate professor of surgery at Yale University School of Medicine in New Haven, Connecticut, told Medscape Endocrinology that the findings "have important implications." Dr. Sosa was not involved with this trial.

"It's an excellent first study," said Dr. Sosa. "I think additional information is needed as several issues were raised but not answered. Who will perform this kind of screening? Should it be performed by obstetricians, endocrinologists, or a combination of the 2?

"One issue that always comes up with regard to screening for thyroid dysfunction in pregnancy is standardization of the thyroid function assays. How are we going to define appropriate ranges?" Dr. Sosa wondered. "They need to be defined for the specific assays used and those need to be carefully defined for practitioners and clinicians."

"Any time you recommend that screening be performed, particularly in the United States given the current healthcare environment, we have to determine whether the costs that will be accrued from the universal screening are justified by the benefits of identifying women with thyroid dysfunction early enough in the pregnancy so that downstream there is benefit not only for them but obviously for the unborn child."

"I would hesitate, based on this study, to completely reform practice and screen all women," continued Dr. Sosa. "I think we need to wait until [the investigators] complete their specific analysis and publish their results. But I think the most important thing is the call to arms that additional studies like this are needed using their data, and potentially replicating it in a different population of patients, such as in the United States."

Dr. Stagnaro-Green and Dr. Sosa have disclosed no relevant financial relationships.

American Thyroid Association (ATA) 80th Annual Meeting: Oral Abstract 6. Presented September 24, 2009.


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