Re: Universal screening versus risk-based protocols for
antibiotic prophylaxis during childbirth to prevent early-onset Group B
streptococcal disease: A systematic review and meta-analysis
Dear Editor,
We read the systematic review and meta‐analysis “Universal screening
versus risk‐based protocols for antibiotic prophylaxis during childbirth
to prevent early‐onset Group B Streptococcal disease” with great
interest.1 This systematic review correctly identified
that overtreatment would occur in both risk-based and universal
screening strategies. While our review,2 cited by the
authors, only estimated the over-detection and potential overtreatment
in a screening strategy and did not compare this to the amount of
overtreatment in a risk-based strategy, we would like to make a few
points about this comparison.
The authors found that there was no difference in the percentage of
women receiving IAP in risk-based or screening protocols (29% versus
31% respectively). However, the impact of screening on the rate of
treatment exposure may depend on the details of the prevention
strategies. It is important to ask what GBS risk factors are included in
a risk-based strategy and, whether pregnant women with these risk
factors, would be offered screening for GBS carriage and offered IAP if
they have a negative GBS screening result in a universal screening
strategy.
In the UK context, an expert panel agreed that universal screening would
be implemented in addition to risk-based prevention and not as a
replacement.3 Consequently, in the UK, screening may
do little to reduce IAP in women who have GBS risk factors, but it would
introduce IAP in a group of predominantly low risk women who carry GBS
at term but most of whom would not have a neonate with EOGBS in the
absence of IAP. Adding screening to risk-based prevention, a model in
the UK estimated that screening would result in 96,260 pregnant women
offered IAP treatment in addition to those already treated within the
risk-based strategy alone.3
It is the balance of the overtreatment and potential harm against the
benefits from screening in this group of pregnant women that is crucial.
The lack of data on the clinically relevant outcomes in babies with
EOGBS born to these pregnant women and the lack of data on the long-term
outcomes of IAP treatment in this group hampers the assessment on both
sides of this equation.2
We agree with the authors that clinical data are needed to verify
whether screening would increase or decrease the amount of IAP exposure
compared with risk-based prevention. We are hopeful that the upcoming
NIHR HTA trial of screening for maternal GBS carriage will shed light on
this in the UK context.4 With respect to screening
itself, clinical data on a range of issues are needed to judge the
impact of this intervention. Data are needed on the long-term outcomes
of EOGBS disease in term births, and the long-term outcomes of IAP
treatment in women with GBS carriage who are at low risk of having a
baby with EOGBS. In addition, choice of place of birth has been
identified as an important element of obstetric care so the impact of
treatment on the experience of birth is another factor that may need to
be considered. Without data on such issues, it is very difficult to
determine that the benefit of universal screening outweighs the harm.
Farah Seedat & John Marshall
UK National Screening Committee Evidence Team, Floor 5, Wellington
House, 133-155 Waterloo Road, London, SE1 8UG.