Preventing early-onset group B streptococcal sepsis: Strategy development using decision analysis

Objective. To evaluate recommended strategies for prevention of early-onset group B streptococcal infections (EOGBS) with reference to strategies opti mized using decision analysis. Methods. The EOGBS attack rate, prevalence and odds ratios for risk factors , and expected effects of prophylaxis were estimated from published data. P opulation subgroups were defined by gestational age, presence or absence of intrapartum fever or prolonged rupture of membranes, and presence or absen ce of maternal group B streptococcus (GBS) colonization. The EOGBS prevalen ce in each subgroup was estimated using decision analysis. The number of EO CBS cases prevented by an intervention was estimated as the product of the expected reduction in attack rate and the number of expected cases in each group selected for treatment. For each strategy, the number of residual EOG BS cases, cost, and numbers of treated patients were calculated based on th e composition of the prophylaxis group. Integrated obstetrical-neonatal str ategies for EOGBS prevention were developed by targeting the subgroups expe cted to benefit most from intervention. Results. Reductions in EOGBS rates predicted by this decision analysis were smaller than those previously estimated for the strategies proposed by the American Academy of Pediatrics in 1992 (32.9% vs 90.7%), the American Coll ege of Obstetricians and Gynecologists in 1992 (53.8% vs 88.8%), and the Ce nters for Disease Control and Prevention in 1996 (75.1% vs 86.0%). Strategi es based on screening for GBS colonization with rectovaginal cultures at 36 weeks or on use of a rapid test to screen for GBS colonization on presenta tion for delivery, combining intrapartum prophylaxis for selected mothers a nd postpartum prophylaxis for some of their infants, would require treatmen t of fewer patients and prevent more cases (78.4% or 80.1%, respectively) a t lower cost. Conclusions. No strategy can prevent all EOGBS cases, but the attack rate c an be reduced at a cost <$12 000 per prevented case. Supplementing intrapar tum prophylaxis with postpartum ampicillin in a few infants is more effecti ve and less costly than providing intrapartum prophylaxis for more mothers. Better intrapartum screening tests offer the greatest promise for increasi ng efficacy. Integrated obstetrical and neonatal regimens appropriate to th e population served should be adopted by each obstetrical service. Surveill ance of costs, complications, and benefits will be essential to guide conti nued iterative improvement of these strategies.