Group B strep in pregnancy: test-and-treat, or just treat?

Journal of Family Practice, Jan, 2008

* Clinical question

Is test-and-treat or simply treating without testing more cost-effective to prevent newborn infection with group B streptococcus?

* Bottom line

The most cost-effective approach is to treat all women with preterm or high-risk term deliveries, while testing and treating low-risk women with term births. This approach avoids the cost of testing without an unreasonable increase in the number of women exposed to antibiotics, which is calculated to be approximately 27% in this approach.

Level of evidence

lb: Individual randomized controlled trials (with narrow confidence interval)

Study design

Cost-effectiveness analysis

Funding

Other

Setting

Not applicable

Synopsis

Screening for and treating group B streptococcal infection during late pregnancy--to prevent infection in newborns--is routinely performed in the US and other countries, but not in the United Kingdom. This cost-effectiveness analysis, conducted from the viewpoint of a funding agency in the UK, evaluated the relative value of: 1) prenatal testing and prepartum antibiotics if the result is positive, 2) treatment of all women, except those with no risk factors, and 3) vaccination during pregnancy, which is not yet available.

The authors included all important outcomes in their analysis; as their unit of measurement, they used the number of quality-adjusted life-years (QALYs) gained for births after 24 weeks of gestation for the lifetime of the child. Costs and utilities were based on a systematic review of the literature; they primarily used published data.

The best approach: treat high-risk and preterm pregnancies. Treat all women with preterm and high-risk term deliveries (11% of all births, on average), while testing and treating women with low-risk term pregnancies. This will prevent almost 30% of infections and yield the highest gain in QALYs, without breaking the threshold for cost-effectiveness, which was set at 25,000 [pounds sterling] per QALY gained.

A vaccination, when available, would change these outcomes. Testing before treating will likely become more cost-effective.

Colbourn TE, Asseburg C, Bojke L, et al. Preventive strategies for group B streptococcal and other bacterial infections in early infancy: cost effectiveness and value of information analyses. BMJ 2007; 335:655-672.