Prenatal syphilis screening rates: Are they being accurately reported?

Prenatal syphilis screening, recommended by the Centers for Disease Control, medical professional organizations, and public health authorities, is critical to preventing still births and serious birth defects in babies of affected mothers.

A study published in the April issue of the journal Sexually Transmitted Diseases reports that state Medicaid statistics, when used to determine screening rates, may seriously underestimate the number of expectant mothers being screened for syphilis.

Researchers led by Marc Rosenman, M.D., of the Indiana University School of Medicine and the Regenstrief Institute compared four years of Medicaid data from the state of Indiana with data from the Regenstrief Medical Record System (RMRS) for women seen in Wishard Health Services. Of the nearly 4,000 women with both Medicaid and RMRS data, only half had evidence of prenatal syphilis screening recorded in Medicaid claims data, while more than 99 percent had at least one laboratory report of syphilis screening recorded in the RMRS, indicating that Medicaid numbers were missing nearly half the women screened.

“What our study points out is that analyses based on Medicaid data might not tell the whole story. And this problem is not unique to Indiana. Our findings add perspective to a CDC-funded study of Florida Medicaid data which reported a prenatal syphilis screening rate of about 50 percent, a rate very similar to what we found in Indiana Medicaid data,” said Dr. Rosenman, an assistant professor of pediatrics at the IU School of Medicine and a research scientist at the Regenstrief Institute.

Why are Medicaid data incomplete? Reasons may vary from how the test is billed to how data are transmitted from a physician's office, clinic or hospital to a state agency.

“Prenatal syphilis screening is a vital step in preventing serious illness. The nearly universal prenatal screening we report is not necessarily typical of other health systems across the state and nation, for a variety of reasons including that this study was conducted at a large public teaching hospital and began during a major syphilis outbreak in Indianapolis in 1998-1999, and since then physicians, health systems, and the county health department have probably all been extra conscientious in encouraging screening. But what is clear is that Medicaid data by far underestimate how much screening is taking place,” said Dr. Rosenman. “The same is probably true of other published estimates based on commercial insurance data.”

Syphilis, a sexually transmitted disease, is on the increase in the United States. A simple blood test is used to screen for the disease. An at-risk woman should be screened for syphilis multiple times during her pregnancy including immediately prior to delivery.