The clinical and cost-effectiveness of testing for Group B Streptococcus: a cluster randomised trial with economic and acceptability evaluations (GBS3)

BACKGROUND Group B Streptococcus (GBS) is a bacterium present in the vagina and lower gut of approximately 1 in 4 pregnant women GBS can come and go throughout pregnancy and is usually symptomless, but may be passed to the baby around birth Approximately one baby in every 1750 will develop a GBS infection within 7 days of birth Most will recover, but each year in the UK about 40 babies die and 1 in 14 of the survivors will have a long-term disability Giving women in labour antibiotics through a drip into their veins reduces the risk of newborn babies developing GBS infection Current UK practice is to offer antibiotics when the baby is at higher risk of developing the infection: if the birth is preterm, if GBS was detected during the current pregnancy, if the woman has a fever or previously had an infected baby This risk factor screening is imperfect: some babies are missed, and many women with risk factors do not carry GBS but receive antibiotics unnecessarily We need a method to identify women carrying GBS, so that only those carrying GBS receive antibiotics A solution is routine testing of every pregnant woman, and offering antibiotics in labour to those who are carrying GBS There are two methods we could use one is to test about 3-5 weeks before the due date with a test that gives a result within 48 hours The other is to use a new rapid test done when the woman is in labour Both tests have advantages and disadvantages AIMS OF THE RESEARCH To establish whether routine testing women (in late pregnancy or during labour), to direct the offer of antibiotics in labour, is better at reducing GBS infection in newborn babies than using the current risk factor approach, and whether it represents value for money for the NHS DESIGN AND METHODS USED We will work with 80 hospitals and birth centres Hospitals will be randomly allocated to the risk factor or the routine testing approach Hospitals allocated to the routine testing approach will be further randomly divided into testing women using a swab taken from the vagina and rectum either a) at 35-37 weeks of pregnancy, using a lab based test or b) in labour, using a rapid test machine Women with a positive test result will be offered antibiotics in labour All mothers in preterm labour or who had a previous baby with GBS infection will be offered antibiotics as per current guidance We will compare the number of babies who develop serious infection born in all routine testing hospitals and birth centres with those using the risk factor approach As infections are relatively rare, we will need to collect information on 320,000 women to be able to see a difference between the two main approaches The allocated testing strategy will be adopted as standard practice by the unit, for which mothers will give standard verbal consent for the test The data used in the trial will be routinely collected data retrieved from NHS databases As such, individual written consent for participation in trial will not be sought We will also interview women and healthcare professionals about the acceptability of the testing approaches (Written informed consent will be obtained for the interviews) Finally, we will compare the overall costs of each strategy and work out which represents the best value for money for the NHS PATIENT AND PUBLIC INVOLVEMENT This study is supported by Group B Strep Support, the national charity working to prevent GBS infections, and by the National Childbirth Trust DISSEMINATION This project will provide the NHS with the evidence required to decide whether GBS routine testing should be implemented in the UK Group B Strep Support and the National Childbirth Trust will use their extensive network of social and mainstream media connections to publicise the results