Group B Streptococcus

Kwatra, Gaurav; Madhi, Shabir А.

doi:10.1016/b978-0-12-814582-1.00012-7

Cited by 1 publication

(2 citation statements)

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“…This sensitivity analysis shows that ADR estimates of thresholds associated to 50% risk reduction is robust to prior specification, and that placing most prior probability on simpler IgG concentration distributional forms can prevent MMA RCD estimates from showing long right tails. Re-analysis of the South African case-control study Data from a South African (SA) case-control study were analyzed by Madhi et al (2020) to investigate the association between IGbsD and serotype-specific anticapsular antibody measurements for serotypes Ia and III. This matched case-control study was nested within an observational study and took place at three academic hospitals in Johannesburg, South Africa between June 2016 and December 2018.…”

Section: Re-analysis Of the Devani Case-control Studymentioning

confidence: 99%

“…Group B Streptococcus (GBS) is an opportunistic commensal gram-positive bacterium colonising intestinal and vaginal flora in 10% to 40% of pregnant women [1][2][3][4][5][6][7][8]. Antenatal maternal GBS infections such as urinary tract infections and chorioamnionitis are major contributors to GBS-associated premature delivery, miscarriages and stillbirths [9].…”

Section: Introductionmentioning

confidence: 99%

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Estimation of invasive Group B Streptococcus disease risk in young infants from case-control serological studies

Izu

Kwatra

Madhi

et al. 2021

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Background: Group B Streptococcus (GBS) infections are a major cause of invasive disease (IGbsD) in young infants and cause miscarriage and stillbirths. Immunization of pregnant women against GBS in addition to intrapartum antibiotic prophylaxis could prevent disease. Establishing accurate serological markers of protection against IGbsD could enable use of efficient clinical trial designs for vaccine development and licensure, without needing to undertake efficacy trials in prohibitively large number of mother-infant dyads. The association of maternal naturally acquired serotype-specific anti-capsular antibodies (IgG) against serotype-specific IGbsD in their infants has been studied in case-control studies. The statistical models used so far to estimate IGbsD risk from these case-control studies assumed that the antibody concentrations measured sharing the same disease status are sampled from the same population, not allowing for differences between mothers colonised by GBS and mothers also potentially infected (e.g urinary tract infection or chorioamnionitis) by GBS during pregnancy. This distinction is relevant as infants born from infected mothers with occult medical illness may be exposed to GBS prior to the mother developing antibodies measured in maternal or infant sera. Methods: Unsupervised mixture model averaging (MMA) is proposed and applied here to accurately estimate infant IGbsD risk from case-control study data in presence or absence of antibody concentration subgroups potentially associated to maternal GBS carriage or infection. MMA estimators are compared to non-parametric disease risk estimators in simulation studies and by analysis of two published GBS case-control studies. Results: MMA provides more accurate relative risk estimates under a broad range of data simulation scenarios and more accurate absolute disease risk estimates when the proportion of IGbsD cases with high antibody levels is not ignorable. MMA estimates of the relative and absolute disease risk curves are more amenable to clinical interpretation compared to non-parametric estimates with no detectable overfitting of the data. Antibody concentration thresholds predictive of protection from infant IGbsD estimated by MMA from maternal and infant sera are consistent with non-parametric estimates. Conclusions: MMA is a flexible and robust method for design, accurate analysis and clinical interpretation of case-control studies estimating relative and absolute IGbsD risk from antibody concentrations measured at or after birth.

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Section: Re-analysis Of the Devani Case-control Studymentioning

confidence: 99%