A population-based comparison of strategies to prevent early-onset group B streptococcal disease in neonates.
BACKGROUND
Guidelines issued in 1996 in the United States recommend either screening of pregnant women for group B streptococcal colonization by means of cultures (screening approach) or assessing clinical risk factors (risk-based approach) to identify candidates for intrapartum antibiotic prophylaxis.


METHODS
In a multistate retrospective cohort study, we compared the effectiveness of the screening and risk-based approaches in preventing early-onset group B streptococcal disease (in infants less than seven days old). We studied a stratified random sample of the 629,912 live births in 1998 and 1999 in eight geographical areas where there was active surveillance for group B streptococcal infection, including all births in which the neonate had early-onset disease. Women with no documented culture for group B streptococcus were considered to have been cared for according to the risk-based approach.


RESULTS
We studied 5144 births, including 312 in which the newborn had early-onset group B streptococcal disease. Antenatal screening was documented for 52 percent of the mothers. The risk of early-onset disease was significantly lower among the infants of screened women than among those in the risk-based group (adjusted relative risk, 0.46; 95 percent confidence interval, 0.36 to 0.60). Because women whose providers had no strategy for prophylaxis may have been misclassified in the risk-based group, we excluded all women with risk factors and adequate time for prophylaxis who did not receive antibiotics. The adjusted relative risk of early-onset disease associated with the screening approach in this secondary analysis was similar--0.48 (95 percent confidence interval, 0.37 to 0.63).


CONCLUSIONS
Routine screening for group B streptococcus during pregnancy prevents more cases of early-onset disease than the risk-based approach. Recommendations that endorse both strategies as equivalent warrant reconsideration.
Respiratory Diseases Branch, MS-C23, Division of Bacterial and Mycotic Disease, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA. zha6@cdc.gov
Stephanie J
SJ
Schrag
Elizabeth R
ER
Zell
Ruth
R
Lynfield
Aaron
A
Roome
Kathryn E
KE
Arnold
Allen S
AS
Craig
Lee H
LH
Harrison
Arthur
A
Reingold
Karen
K
Stefonek
Glenda
G
Smith
Melanie
M
Gamble
Anne
A
Schuchat
D000704:Analysis of Variance; D019072:Antibiotic Prophylaxis; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007743:Labor, Obstetric; D008297:Male; D008403:Mass Screening; D008484:Medicaid; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis* / Q000188:drug therapy; D011295:Prenatal Care; D011296:Prenatal Diagnosis; D012189:Retrospective Studies; D012307:Risk Factors; D013290:Streptococcal Infections / Q000175:diagnosis / Q000517:prevention & control*; D013292:Streptococcus agalactiae / Q000302:isolation & purification