Evaluation of Congenital Syphilis Surveillance System -- New Jersey, 1993

To monitor disease burden and trends associated with congenital syphilis (CS), effective prevention programs require a surveillance system that identifies CS cases in an accurate and timely manner. Before 1988, comprehensive CS surveillance was difficult for health departments to conduct because documentation of infection in infants required complex and costly long-term follow-up for up to 1 year after delivery; follow-up often was incomplete, and many infected infants were not identified. To estimate the public health burden of CS more accurately and eliminate long-term follow-up of infants by health department personnel, in 1988 CDC implemented a new CS case definition (1). Rather than relying on documentation of infection in the infant, the new case definition presumes that an infant is infected if it cannot be proven that an infected mother was adequately treated for syphilis before or during pregnancy (2). During 1993-1994, the Sexually Transmitted Disease Prevention and Control Program of the New Jersey Department of Health (NJDOH) evaluated its CS surveillance system to assess the accuracy and completeness of reporting using the new case definition and to determine the personnel costs associated with identifying and classifying CS cases. This report summarizes the results of the evaluation.

New Jersey statutes mandate that all pregnant women receive a serologic test for syphilis (STS) during pregnancy or at delivery if no test was done during pregnancy. Newborns also routinely receive a STS at birth if born to a mother with a reactive STS. Laboratories are required to report all reactive STSs (including maternal, delivery, and newborn) to the NJDOH, and all such reports are investigated by NJDOH. Investigation activities include reviewing infant and maternal medical records to determine whether syphilis was previously diagnosed, reviewing laboratory results and health department records to determine the mother's treatment status, and verifying missing information by contacting the patient and/or provider by telephone or field visit.

For this analysis, reports of all reactive STSs for newborns received by NJDOH during January 1-December 31, 1993, were reviewed manually to assess the completeness and accuracy of case classification and reporting. Infants with reactive STSs had been classified using the four categories recommended by CDC: 1) not infected, 2) syphilitic stillbirth, 3) confirmed case of CS, and 4) presumptive case of CS (1,2). Costs associated with investigation and follow-up of reactive STSs for newborns were estimated by multiplying the average time spent at each task by the hourly wage (excluding benefits) of the person performing the task. Time spent on an investigation was determined by interviewing the persons who performed the tasks.

During 1993, a total of 497 reactive STSs for newborns were reported to NJDOH. Of these reports, 266 (53%) had been classified as not infected, but reactive secondary to passive transfer of maternal syphilis antibodies from a mother adequately treated for syphilis before or during pregnancy, and 143 (29%) as presumptive cases. In addition, a total of 10 (2%) reports initially classified as not infected were reclassified as presumptive cases, and 78 (16%) reports were still under investigation.

For 1993, the estimated average cost of investigating one reactive STS for a newborn using routine surveillance methods was $183. Based on an average of 41 reactive STSs for newborns reported to NJDOH each month in 1993, the estimated costs for investigation and follow-up were $7500 per month or $90,000 per year. Reported by: L Finelli, E Napolitano, J Carolina, STD Prevention and Control Program; K Spitalny, MD, State Epidemiologist, New Jersey State Dept of Health. Surveillance and Information Systems Br, Div of Sexually Transmitted Diseases and HIV Prevention, National Center for Prevention Svcs; Div of Field Epidemiology, Epidemiology Program Office, CDC.

Editorial Note

Editorial Note: CS is a serious and totally preventable disease that results from in utero infection of the fetus with Treponema pallidum, a thin, motile spirochete. Complications of CS include intrauterine growth retardation, bone abnormalities, and failure to thrive. Up to 40% of pregnancies in women with untreated syphilis result in fetal or perinatal death (3,4). CS can be prevented by screening and treating women for syphilis before or during early pregnancy (1,5). CDC recommends screening women at high risk for syphilis during the first and third trimesters of pregnancy (1). Screening for syphilis at delivery primarily ensures that infants born to women in whom syphilis previously was either unidentified or untreated are identified and treated.

The new CS case definition was implemented to provide a more accurate measure of the impact of CS by eliminating long-term follow-up of STSs and by including asymptomatic infants at risk for CS (i.e., who require treatment but who were not counted by the previous case definition). However, the existing reporting infrastructure in many health departments may need to be changed to allow full benefit from the new case definition (6). Despite use of the new case definition for CS, the findings in the NJDOH study indicate that the number of CS cases in New Jersey may still be underestimated because of inaccuracy and incompleteness of CS surveillance data. In this report, the presumptive cases incorrectly classified as not infected and the incomplete case reports accounted for nearly 20% of all reported STSs for newborns during 1993. Reasons for misclassification of cases and incomplete reporting may reflect a lack of understanding by health department staff of the epidemiology of CS, the new CS surveillance case definition, and CS reporting instructions (2).

In response to the findings of this study, NJDOH initiated an intervention trial in March 1994 to improve the timeliness, accuracy, and completeness of CS surveillance data. As part of the intervention, NJDOH collaborated with three local hospitals that provided delivery services to women at high risk for syphilis. These hospitals established a policy to notify NJDOH within 24 hours of admission of each pregnant woman with a positive STS who was admitted for delivery. On notification and before the patient was discharged from the hospital, NJDOH performed medical record reviews and patient/provider interviews. Using these procedures, the time required for health department staff to complete investigations was reduced from an average of 10 hours to 3 hours per investigation. If this policy were expanded to most hospitals that deliver high-risk infants, NJDOH personnel costs associated with CS case investigations could be reduced substantially, and accuracy and timeliness of reporting could be improved.

References

1. CDC. Guidelines for the prevention and control of congenital syphilis. MMWR 1988; 37(suppl no. S-1).

2. CDC. Congenital syphilis case investigation and reporting instructions. Atlanta: US Department of Health and Human Services, Public Health Service, CDC, 1992.

3. CDC. Congenital syphilis -- New York City, 1986-1988. MMWR 1989;38:825-9.

4. Schultz KF, Cates W, O'Mara PR. Pregnancy loss, infant death, and suffering: the legacy of syphilis and gonorrhea in Africa. Genitourin Med 1987;63:320-5.

5. Petrone ME, Teter MJ, Freund CG, Porter J, Parkin WE, Spitalny KC. Epidemiology of congenital syphilis. N J Med 1989;86:965-9.

6. Zenker PN, Berman SB. Congenital syphilis: reporting and reality {Editorial}. Am J Public Health 1990;80:271-2.

   
   

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