Keywords
Group B streptococcus, meningitis, sepsis, infants, children, impairment, neurodevelopment, disability, economic, cost
Group B streptococcus, meningitis, sepsis, infants, children, impairment, neurodevelopment, disability, economic, cost
Revision to table 2 and text to clarify the study inclusion/exclusion criteria. Minor updates to text to clarify link between this study and the full public health value proposition for GBS maternal vaccination, which is a broader exercise than the analysis described in this paper.
See the authors' detailed response to the review by Tina Perme
See the authors' detailed response to the review by David Kaslow
The United Nations Sustainable Development Goals (SDGs) aim to complete the unfinished agenda for child survival and ensure that every child has the opportunity to thrive, including reaching their developmental potential1,2. While SDG3 continues to center on the reduction of neonatal and child mortality, SDG4 incorporates specific targets and indicators to address early childhood development (UN SDG, 2015). It is recognized that preventable infections, such as those that cause meningitis, neonatal sepsis, and pneumonia, are an important cause of neonatal and infant death3. However, their contribution to neurodevelopmental impairment (NDI), which encompasses both developmental delay (two or more developmental domains in children ≤5 years old) and disability (impairment in a child’s physical, learning, language, or behavior function) has been under-appreciated. As child deaths are reduced in low- and middle-income countries (LMIC), neurodevelopmental impairment may increase, especially if access and quality of early childhood developmental programs is sub-optimal4,5.
Invasive group B Streptococcus (iGBS) disease during the first months of life is one of the infections that might have important long-term consequences for children. This infection often presents as sepsis or meningitis and was responsible for an estimated 90,000 (uncertainty range [UR]: 36,000-169,000) infant deaths in 20156. Survivors of iGBS disease in early life may develop long-term NDI. Of 18 studies identified in a recent review of the risk of NDI in children with history of iGBS disease7, only three were from middle-income countries and none were from low-income countries where the majority of iGBS disease cases occur. In these studies, NDI was defined as problems of body function and structure, such as significant deviations or loss in intellectual and/or motor, vision, or hearing impairment. The review concentrated on infants with GBS meningitis, highlighting a key data gap related to long-term adverse outcomes in infants who develop GBS-associated sepsis. Only a small number of older studies (primarily from the 1970s) reported NDI outcomes in children older than 2 years, which would have missed impairment outcomes that do not manifest until later in childhood. Although, a recent study from Denmark and the Netherlands has added to this data gap for high-income countries8, data from LMIC remains a key gap.
Intrapartum antibiotic prophylaxis (IAP) has reduced the incidence of early-onset iGBS disease in some high-income countries9,10; however, this approach is less effective in preventing late-onset invasive disease11 and thought not to significantly affect other consequences of maternal GBS colonization, notably GBS-associated stillbirths and preterm births. Maternal vaccination against GBS is a promising alternative that could protect both mothers and infants against iGBS disease. To guide investment in maternal vaccines targeting GBS, it is necessary to estimate the health and economic burden caused by the disease globally12. Studies on mortality and morbidity due to GBS among pregnant and postpartum women, stillbirths, and infants have been recently reviewed and meta-analyzed13. These reviews uncovered two major data gaps that significantly hinder these analyses: the lack of long-term follow-up data amongst survivors, which are needed to calculate generic health-related utility measures such as quality-adjusted life years (QALYs) or disability-adjusted life years (DALYs) to allow comparison with other diseases, and the lack of primary data regarding long-term economic consequences to households of children with a history of iGBS disease.
Data on the costs associated with iGBS disease, which are needed to inform cost-effectiveness analysis and investment decisions on the development and deployment of new vaccines, are scarce. We are only aware of a single study undertaken in the UK that directly assessed the economic costs of iGBS disease beyond the acute episode14. This showed that over the first two years of life, the health and social care costs of infants with a history of iGBS disease were almost twice that of children with no history of iGBS disease. Although there are more studies that report on the acute costs of infant sepsis/meningitis, these are generally from high-income countries and are not GBS etiology specific15. To better understand the life-course consequences of infant iGBS, data on health and economic outcomes needs to be collected in studies that include older children and adolescents across multiple settings.
In this paper, we present the protocol for a multi-country epidemiological study, coordinated by the London School of Hygiene & Tropical Medicine. The main aim of the study is to estimate the risk of NDI and socioemotional behaviors in children who survived neonatal or infant iGBS. The study will also measure long-term health related quality of life (HRQoL) and economic costs that arise as a consequence of iGBS, as well as the acute costs of sepsis and meningitis in young infants. Beyond the direct estimation of these outcomes in our study population, this study is also part of a collaboration with the World Health Organization (WHO) to inform development of a full public health value (FPHV) proposition for maternal vaccines against GBS16.
Our objectives in designing this study were:
Objective 1 - Long-term neurodevelopmental impairment:
(a) Primary objectives:
1. To estimate the risk of moderate/severe NDI in children with history of iGBS disease in early-infancy, and to compare this with the risk in children with no known history of iGBS
2. To estimate the risk of mild and moderate/severe socioemotional behavior outcomes in children with history of iGBS, and compare with risk in children with no known history of iGBS
Objective 2 – Long-term mortality: To assess mortality beyond initial hospital-discharge among children who had iGBS.
Objective 3 – Long-term economic costs and health-related quality of life:
(a) Long-term economic consequences: To measure the long-term economic costs to the healthcare system, households and society associated with infant iGBS.
(b) Health-related quality of life: To collect information needed to calculate the difference in QALYs between children with a history of iGBS, and those with no history of iGBS.
Objective 4 – Short-term economic consequences: To estimate the costs to the healthcare system and households during acute episodes of sepsis and meningitis (irrespective of etiology) in neonates and young infants.
Long-term outcomes after iGBS disease in infancy (Objectives 1, 2, 3). We will use a matched cohort study design to collect data on NDI, socioemotional behavioral, and economic outcomes for survivors of iGBS in early infancy. Children with a history of infant iGBS (henceforth iGBS survivors), will be identified via hospital records in study sites, Health and Demographic Surveillance Systems (HDSS), or among participants of previous epidemiological studies. Children with no history of iGBS (henceforth, the non-iGBS comparison group) will be identified and matched to iGBS survivors based on sex and birth month and year. In Mozambique, children will also be matched on neighborhood location.
Acute costs of neonatal sepsis and meningitis study (Objective 4). In addition to the main study measuring long-term economic outcomes, we will undertake a separate study to quantify the acute costs to the healthcare system and household linked to neonatal sepsis and meningitis. This study will involve a different study population: prospectively identified neonates admitted for clinically suspected sepsis or meningitis irrespective of the underlying etiology. Data on the costs associated with the period of acute hospitalization will be collected following discharge.
Since the major data gap on the long-term outcomes of iGBS survivors is in LMICs, this study was designed to collect data in these settings, including at least one country per GBS high-burden region (Africa, Asia, Latin America). For this collaborative work, we shared a call for data through multiple channels in 2018, including targeting previous collaborators, experts and known GBS researchers, scientific conferences and meetings, as well as sending direct requests from WHO headquarters to country offices and placing posts on social media platforms to reach the widest number of people. With these various approaches we aimed to ensure better geographical representation than currently seen in the literature. Among those who responded, potential study sites were identified based on the following criteria: (a) sites that had at least 10 post-discharge surviving iGBS cases that could be enrolled; (b) sites that had neurodevelopmental follow-up data or the ability to collect this type of data in children aged at least 3 years; (c) sites where the expected loss to follow-up was <20%. From those who expressed an interest in joining this project and fulfilled the above criteria, research teams from Argentina, India, Kenya, Mozambique and South Africa agreed participate in this work and lead investigations locally (Table 1).
In Argentina, the local study will be performed by the research organization Fundación Infant, in Buenos Aires; in Southeast India, the research activities are led by the Christian Medical College in Vellore; in Kilifi, Kenya, the work is being undertaken by KEMRI-Wellcome Trust Research Programme; in Mozambique, children are being recruited at the Manhiça Health Research Centre, in collaboration with the Barcelona Institute for Global Health; and in South Africa, the project is being led by the South African Medical Research Council Vaccines and Infectious Diseases Analytical Research Unit (VIDA).
Study populations. In the Kenya and Mozambique sites, which are also HDSS sites, parents of potential study participants, based on the HDSS database, will be contacted through standard recruitment procedures. Hospital records, which are linked to the HDSS database, will be used to identify all children who have been admitted with iGBS based on the case definition. The HDSS database will also be used to select matched non-iGBS children from the community.
In Argentina and India, hospital-based databases will be used to identify potential iGBS survivors and non-iGBS children using standard practices established by each site. Hospital-based databases will be used to identify children who have been admitted with iGBS based on the case definition. Hospital-based birth registries will be used to select matched non-iGBS children.
In South Africa, the same cohort of iGBS survivors and non-iGBS children from three epidemiological studies that were conducted between 2012 and 2015 will be contacted for re-enrolment. These participants are expected to be 5–7 years old and originally consented to be followed until the age of 5. Using the study database, parents or primary caregivers of these children will be contacted by phone for interest and be given information about participating in the new study.
Case definition and exclusion criteria. Children with a previous diagnosis of either GBS meningitis or GBS sepsis in the first 90 days of life (days 0 - 89) will be recruited in these local epidemiological studies. Enrolment of children with a history of GBS sepsis is important to increase the, currently limited, number of studies with data on long-term disability post-GBS sepsis7. Table 2 below summarizes the case definition and the clinical and microbiological eligibility criteria used by each study site for identification of exposed and unexposed children in this study.
In Argentina, India, Kenya, and Mozambique iGBS children and GBS unexposed children born early than 32 weeks of gestation are excluded. In South Africa, gestational age is not an exclusion criterion (Table 2).
pSBI, possible serious bacterial infection; CSF, cerebrospinal fluid; PCR, polymerase chain reaction. pSBI definition: Any one of the following: a history of difficulty feeding, history of convulsions, movement only when stimulated, respiratory rate of 60 breaths per min or more, severe chest in-drawing, temperature ≥ 37.5°C or ≤35.5°C.
Sample size and power calculation. The number of iGBS survivors included in the matched cohort study of long-term outcomes was based on the maximum number of cases expected to be identified, accounting for 20% being unreachable, ineligible or who refuse participation. The expected number of iGBS survivors for each site is summarized in Table 3. Based on anticipated recruitment of 200 iGBS survivors and a 1:3 ratio of matched non-iGBS children, and assuming a prevalence of our primary outcome (moderate/severe NDI) of 26% in iGBS survivors and 10% in the non-iGBS comparison group (based on a study of meningococcal serogroup B survivors18), a pooled analysis would be able to detect this difference using a two-sided test of binomial proportions with 99% power at a 5% significance level. Mild developmental impairment is likely to be more prevalent among iGBS survivors, including those with sepsis. Our power to detect a difference in the risk of overall NDI (including mild NDI) would be 78%, assuming detection of 32% and 20% NDI in iGBS survivors7 and non-iGBS children19, respectively.
Site/Country | Expected number children with history of iGBS |
---|---|
Argentina | 40 |
India | 30 |
Kenya | 50 |
Mozambique | 40 |
South Africa | 40 |
Study procedures and data collection. Trained fieldworkers will contact the parents/primary caregivers of these potential participants about the study by phone (Argentina, India, South Africa) or in-person (India if phone contact information is not available, Kenya, Mozambique) and those contacted will be asked to make a one-time visit to the health facility with their child. Reasons for non-participation, such as migration, refusal or death will be recorded.
Children enrolled in the study and their main caregiver will receive an in-person assessment visit. Written informed consent will be obtained in-person either at the time of the initial house visit or before the in-person assessment visit. Only if appropriate consent/assent is obtained, will the child be enrolled in the study.
At the in-person assessment visits, the following information will be collected:
- Questionnaire to collect participant details including birth and medical history, education, household demographic and socioeconomic data, as well as economic outcomes (for details on economic outcomes see section Economic outcomes and health related quality of life)
- Age-specific neurodevelopmental assessment tools including several domains (motor, vision, hearing, cognitive, language, socioemotional), an epilepsy screening questionnaire, and anthropometric measures (see section on Assessment of developmental outcomes)
- EQ-5D-3L questionnaires to assess the health-related quality-of-life (HRQoL) of study participants and their main caregiver (see section Economic outcomes and health related quality of life).
Data will be collected on paper forms or using a customized app (developed in collaboration with icddr,b, Bangladesh). The customized Android tablet-based app includes questionnaires and neurodevelopment assessment tools, translated into local language where relevant (Figure 1).
Assessment of neurodevelopmental impairment (Objective 1). In this multi-country study, we will use several tools to diagnose NDI and socioemotional and behavioral outcomes in children over a wide age range from 18 months to 17 years old. The inclusion of children older than those enrolled in the majority of the previous epidemiological studies enables us to use more complex developmental assessments designed for older ages to detect specific mild NDI and other developmental delays. By including a wider age range, we can also better understand the developmental trajectory of infants who have survived iGBS. The developmental domains of interest are motor, vision, hearing, cognitive, language, and socioemotional; their definitions, by severity, are described in the Data analysis section. We will also explore growth outcomes and epilepsy.
The diagnostic tools used to identify NDI and other developmental measurements will be administered by experienced assessors, clinical psychologists and pediatricians, who will also perform clinical exams to identify impairment in hearing, motor and vision domains. Each local research team decided which neurodevelopmental assessment tools are appropriate for their setting, based on child’s age and cultural appropriateness or validation of the instrument and technical capacity of each site. There will be 26 different assessment tools and tests being used across the 6 neurodevelopmental domains, as well as anthropometric measurements for growth and an epilepsy screening questionnaire. Table 4 shows the matrix of assessments for each developmental domain, by age category and study site. When a need for further assessment and clinical management is identified, children will be appropriately referred into each site’s existing referral systems.
Sites | |||||
---|---|---|---|---|---|
Argentina | India | Kenya | Mozambique | South Africa | |
Motor | |||||
< 5 years old | Pediatric clinical exam | BSID* BOT‡ | KDI* | MDAT | N/A |
5 – < 10 years old | BOT‡ | Bolts and Nuts Bead Threading | CANTAB | GMDS- ER | |
≥ 10 years old | Stork Balance Ball Balance | N/A | |||
Cognition | |||||
< 5 years old | WPPSI† | BSID* WPPSI† | KDI* Big/small stroop | MDAT | N/A |
5 – < 10 years old | WPPSI† WISC 4¥ | WPPSI† WISC 5¥ | RCPM Tower of London | CANTAB | GMDS- ER |
≥ 10 years old | WISC 4¥ | WISC 5¥ | RCPM Trail Making | N/A | |
Language | |||||
< 5 years old | WPPSI† | BSID* | KDI* PVT, Measures of pragmatics | MDAT | N/A |
5 – < 10 years old | WPPSI† | WPPSI† | Kilifi Naming Test Measure of Pragmatics and Syntax | CANTAB | GMDS- ER |
≥ 10 years old | WISC 4¥ | WISC 5¥ | N/A | ||
Hearing | |||||
≤ 4 years old | Screening test: Distraction test Further testing: ABR | N/A | |||
> 4 years old | Screening test: Tuning fork, Diagnostic memory audiometer Further testing: ABR | ||||
Vision | |||||
≤ 3 years old | LEA symbols Chart or Picture chart | N/A | |||
> 3 years old | Visual acuity app/Tumbling E chart/Snellen chart | ||||
Socioemotional | |||||
≤ 6 years old | CBCL-preschool | ||||
> 6 years old | CBCL- school aged | ||||
Epilepsy | |||||
All ages | Epilepsy Screening Questionnaire (ESQ) |
*BSID assessment up to 42 months.
† WPPSI assessment in Argentina 3-7 years. WPPSI assessment in India 4-7 years.
‡ BOT assessment ≥4 years.
¥ WISC 4 and WISC 5 assessment ≥7 years.
ABR, auditory brainstem response; BOT, Bruininks-Oseretsky Test; BSID, Bayley Scales of Infant and Toddler Development;
CANTAB, Cambridge Neuropsychological Test Automated Battery; CBCL, Child Behavior Checklist; GMDS-ER, Griffiths Mental
Development Scales – Extended Revised; KDI, Kilifi Developmental Inventory; MDAT, Malawi Developmental Assessment Tool; PVT, Picture Vocabulary test; RCPM, Raven’s colored progressive matrices; WISC, Wechsler Abbreviated Scale of Intelligence; WPSSI, Wechsler Preschool and Primary Scales of Intelligence.
Mortality outcome (Objective 2). Whenever feasible, data on the cause of death will be captured through a variety of methods, including by reviewing medical records, verbal autopsy reports and interviews with parents, for iGBS survivors who died after the acute episode and before enrolment and for matched non-iGBS group who died. In Kenya, the list of iGBS survivors who could potentially be enrolled in the study only included children alive at the time of enrolment, therefore data on early mortality post-iGBS disease will not be collected in these sites.
Long-term economic costs and health-related quality of life outcomes (Objective 3). There are only limited data available on the economic consequences of iGBS, which cover only healthcare costs in the first two years of life15. In this study, we will collect information on variables that will allow comparisons of economic outcomes in families of iGBS survivors versus families of the non-iGBS comparison group. These data will also be used to inform future economic analyses that will be performed to assess the value of maternal vaccines against iGBS.
A summary of key economic variables is shown in Table 5. Information collected will include details of the monthly household income and expenditure, participating children’s healthcare utilization, out-of-pocket payments, and any expenditure on social care or special education in the 12 months preceding study enrolment. Additionally, information will be collected on time spent by the main caregiver providing informal care to the participant, as well as information on the costs of coping strategies, such as borrowing and asset sales. Information on the HRQoL of both the participant and the main caregiver will be collected using an EQ-5D-3L questionnaire in three countries where country-approved translations are available: Argentina (Spanish), India (English, Telugu, Tamil) and South Africa (English, Zulu).
Case definition for neonatal sepsis and meningitis. To be able to collect data on acute costs, both cases of severe neonatal infection linked to GBS and cases of severe neonatal infection due to other bacteria will be enrolled, as the number of confirmed iGBS cases per hospital is anticipated to be small over the duration of our study. Participants will be babies admitted with a diagnosis of clinically suspected neonatal infection (sepsis or meningitis) combined with isolation of a pathogenic microbiological agent by culture or detection by polymerase chain reaction (PCR) in a normally sterile site (blood/CSF) on day 0 – 89 of an infant’s life. Babies born at <32 weeks of gestational age, born with severe congenital abnormalities, or with culture positive results only for organisms considered to be contaminants or skin commensals will be excluded (Table 6). In Mozambique the cases will be defined based on clinically suspected sepsis or meningitis because the number of bacteriologically confirmed cases is anticipated to be low due to the size of the hospital.
Sample size. At least 20 participants will be recruited in each of the four sites. The sample size of 20 per site was set as a practical minimum, considering both available resources and also a consensus by local research teams that this would be a feasible number to capture given the anticipated number of neonatal infections within the timeframe of data collection activities.
Study procedures. Participants will be identified prospectively either on admission or using clinical databases. Additionally, in India recent cases (within three months before the start of the study) will also be identified retrospectively from clinical records. Details on hospital resource use will be collected from medical records, including information on length-of-stay, type of hospital bed, and details of any drugs, diagnostic tests and surgical procedures. To capture the wider impacts of a participant's hospitalization, a questionnaire will be administered to the main caregiver, either at time of discharge, or by follow-up as soon as possible after discharge, to collect details on household demographics and economic impact. This will include any out-of-pocket payments, costs related to travel, accommodation, and caregiver time. Data will be gathered on the main caregiver’s HRQoL using an EQ-5D-3L questionnaire and the main caregiver will be asked to estimate their child’s HRQoL during their time in hospital using a Visual Analog Scale (VAS). The main caregiver will be encouraged to accompany the child to the assessment visit, but in the cases where they do not then these sections of the questionnaire will not be completed. No questionnaires will be administered in the case that a participating child dies in hospital, but data will still be collected from hospital records.
Data will be stored on secure servers locally after the end of the study, and anonymized data will be transferred to the team at the London School of Hygiene & Tropical Medicine, where data from different countries will be pooled. Analyses will be conducted jointly by all study partners.
Objective 1 - Long-term neurodevelopmental impairment. To allow comparison between the different neurodevelopmental assessments being used in each of the five sites, we will undertake a mapping activity across all 26 tools by age bands (1–4, 5–9, 10+). The age bands are constructed based on key periods of development17. We will map similar constructs across the different assessments; e.g., gross motor measurements from all relevant tools will be mapped against each other allowing us to compare gross motor development across sites. We will do this for the following domains; gross motor, fine motor, cognitive and language. We will also do a similar mapping activity between the preschool and school-aged CBCL for the socioemotional and behavioral outcomes (e.g., anxiety, ADHD, and autism). Definitions domain-specific neurodevelopmental impairment and severity are described in Table 7.
In India, Kenya, Mozambique, and South Africa, motor and cognitive scores will be normalized using standard reference populations by assessment and site. In Argentina, where motor impairment is being assessed through a clinical exam, description of functional impact will be used.
Vision impairment will be defined using WHO categories of mild (visual acuity in best eye ≤6/12), moderate (visual acuity in best eye ≤6/18 and >6/60), severe (visual acuity in best eye ≤6/60 and >3/60), and blindness (visual acuity in best eye ≤3/60)20,21.
Any hearing impairment will be defined as an unaided hearing threshold in the best ear of >26 decibels and further categorized into mild (audiometric hearing threshold level 26–30 decibels), moderate (threshold level 31–60 decibel), and severe/deafness (threshold level >60 decibel)20,22. In South Africa and Mozambique, screening tests will be used first to identify any individual with any potential hearing impairment. Results from further diagnostic tests will be used to classify into impairment severity as categorized above.
Socioemotional behavior measures will be defined in all sites using the CBCL assessment. The main scoring is based on a principal components analysis that grouped sets of behaviors into different syndrome scales: (1) internalizing problem scales, which include anxious/depressed, withdrawn-depressed, and somatic complaints scores; and (2) externalizing problem scales, which includes rule-breaking and aggressive behavior. There is also a total problem score which is the sum of all the items. Each syndrome, internalizing and externalizing problem score, and total score can be categorized into normal (<93rd percentile), borderline (93rd-97th percentile), or clinical behavior (>97th percentile) based on the same normative samples to create standard scores based on sex and age for all sites.
There are 2 primary outcomes in this study, moderate/severe NDI and moderate/severe behavioral outcomes.
Moderate/severe NDI will be defined as:
- Score of >2 SD below the standardized reference mean in cognition AND/OR motor composite measures
- AND/OR hearing loss
- AND/OR vision loss
Moderate/severe behavioral outcomes will be defined by scores within clinical ranges of ≥1 domain(s) of the problem scales.
Mild NDI (including socioemotional behavior outcomes) will be defined as:
- Score of 1-2 SD below the standardized reference mean in cognition AND/OR motor composite measures
- AND/OR mild hearing loss
- AND/OR mild vision loss
- AND/OR borderline clinical range in at least one domain of the problem scales from the CBCL
We will further assign individuals into the following multi-domain impairment categories based on severity (adapted from 23):
- Mild if child is classified as mildly impaired in ≤2 domains
- Moderate if child is classified as mildly impaired in 3 domains OR classified as moderately impaired in 1 domain & classified as mildly impaired in 2 domains
- Severe if child is classified as moderately impaired in ≥2 moderate domains OR severely impaired in ≥2 domains
The distribution of mild and moderate/severe neurodevelopmental outcomes will be summarized for children with history of iGBS disease and the non-iGBS comparison group and further stratified by clinical syndrome (sepsis and meningitis). We will test the association between history of iGBS disease in early-infancy and moderate/severe NDI in a pooled analysis using a logistic regression accounting for matching factors of age and sex. As gestational age is likely to be an important confounder, we will adjust for this. We will also adjust for other known confounders (e.g., SES, maternal education), if the data allows.
Objective 2 - Mortality. For iGBS survivors, and their matched non-iGBS comparison group, that were reachable (i.e. for whom we have information), we will describe the proportion of children who died before enrolment in each site. Where available, we will also describe the causes of death in both iGBS and non-iGBS groups.
Objective 3 - Long-term economic and health-related quality of life. We will assess the impact of iGBS on economic outcomes including healthcare utilization and costs, household out-of-pocket payments, household income and social care payments, and time spent by the main caregiver on informal care. The cost of hospital stays and attending outpatient clinics will be estimated using published unit costs (e.g. WHO-CHOICE)24. We will compare these outcomes between the iGBS and non-iGBS groups in each study site. If data allow, we will also analyze differences in costs and healthcare utilization linked to NDI. Information from EQ-5D-3L questionnaires will be used to estimate differences in QALYs of both children and their caregivers associated with a history of iGBS disease.
Objective 4 – Acute costs of neonatal sepsis and meningitis. Data from the sub-study on acute costs will be used to estimate the average length-of-stay, use of supportive care, drugs and diagnostics, during hospitalization for the acute neonatal sepsis/meningitis episode. These data will also be used to calculate the overall cost per episode. Other variables will be presented descriptively to characterize the impact of severe neonatal infection.
Written informed consent will be obtained from parents or guardians. Whenever appropriate, based on local guidelines, assent will also be obtained from children participating in the study. The overarching protocol for this multi-country observational study was granted ethical approval at the London School of Hygiene & Tropical Medicine (approval number 16246). Institutional review boards in each of the operating countries granted ethics approval (Argentina approval number Protocol EGB-1, India approval numbers 11723 (CMC Vellore), 2019–7034 (ICMR); Kenya approval number SERU/CGMR-C/164/3882; Mozambique approval numbers 98/CNBS/2019; South Africa approval number M190241), as well as the institutional review board of the World Health Organization (approval number ERC.0003169).
This multi-country study will provide new data on the consequences of iGBS, which is responsible for significant morbidity, disability and mortality in infants10,19. In particular, we will provide novel data on NDI and socioemotional and behavior outcomes, especially in LMIC contexts. Previous reviews have not included any low-income country data, outcomes due to GBS-associated sepsis, or mild NDI17. Mild NDI may be common, impact families and societies, and are required to estimate DALYs, which are widely used as metrics to set priorities for resource allocation.
An important strength of this study is the inclusion of older children (3–17 years) representing three continents (Latin America, Africa, Asia), which currently have limited local data on NDI, socioemotional behavior outcomes, and wider socioeconomic consequences following iGBS disease. This will allow better understanding of the geographic variability on the risk of long-term disability linked to GBS. No previous studies have reported on the potential long-term (>2 years) consequences of GBS in these countries7. Furthermore, our study population will include both children who developed sepsis and meningitis. Some studies suggest that severe NDI might be lower in children developing sepsis compared to meningitis25,26. However, since sepsis is more common among neonates with serious bacterial infection in LMIC settings5, even mild NDI could make an important contribution to the overall morbidity of iGBS. In addition to the risk of long-term morbidity, iGBS may also lead to excess mortality after the acute episode. Although our study is not powered to compare mortality risk in iGBS survivors versus those without history of iGBS, we will be able to describe mortality and causes of deaths in four of five sites.
Another strength of our study is the collection of primary data on healthcare use, income, and HRQoL across multiple countries, which will enable us to identify where iGBS disease may lead to worse outcomes. Adverse economic outcomes due to iGBS are thought to be likely, for example costs linked to sequelae that necessitates frequent healthcare utilization, costly household adaptations, and additional time spent on caregiving to support a child with disabilities23,27. However, to our knowledge, only one study in the UK has directly measured the economic costs of iGBS. In that study, where children were followed-up to the age of two, the average health and social care costs were substantially higher amongst those with history of iGBS14.
A major challenge of this study is the use of different developmental assessment tools in each country, and the complexity of combining multi-domain and neurodevelopmental outcomes for different age bands and multiple tests. We will try to ensure measurement equivalence and comparability of the NDI outcomes between different ages, assessment tools and sites through domain mapping of assessment tools, before individual-level data from each site is further combined for analysis.
A further challenge is the impact that the global coronavirus (COVID-19) pandemic will have on recruitment and research activities, which are not clear. We will continue to assess the situation and are working closely with research teams from each and collaborative institutes to safely undertake field activities in line with each country’s guidelines.
As well as the direct analysis of the data described in this protocol, findings from this study will also be used to update previous morbidity estimates of the global burden of infant iGBS disease13, adding relevant data on long-term outcomes. This will include information to estimate lifetime disability, including risk of NDI, and societal impacts following GBS-related sepsis and meningitis. These additional morbidity estimates, combined with the previously published data on mortality and morbidity of pregnant and postnatal women and stillbirths, along with other literature, will serve as data inputs for both mother and infant GBS disease to update estimates of the overall public health burden of iGBS. Disease burden estimates will be translated into DALYs incurred based on the latest available epidemiologic data, while responses to the quality of life instruments combined with mortality data will be used to estimate QALYs lost. These estimates will be an important input feeding into future cost-effectiveness analyses.
These findings will contribute to the WHO-led development of a full public health value proposition for GBS maternal immunization to inform strategic planning of GBS vaccine research, development, and future implementation. Decision making by multiple stakeholders in the GBS vaccine development process, including research funders, manufacturers, donors and national governments, will be shaped by these findings. Data generated from this study will be linked with research outputs providing more regional and country specific details, allowing countries to utilize the findings in their own context. This will help reduce the translational, marketing, and implementation gaps for the development and introduction of a new GBS vaccine in LMICs which experience some of the highest disease burden.
Most of the mortality and morbidity of iGBS occurs in low-resource settings where there continues to be a paucity of data. As well as the limited epidemiological and clinical data, there are major gaps in data on the economic burden of both short-term and the long-term effects of iGBS. Our study will address limitations in the data currently available, providing new data on epidemiological and economic outcomes are needed to get a more complete picture on the consequences of iGBS for individuals and their families. Coordinated data collection across different settings together with harmonized analysis approaches, will maximize the value of the collected data. The results of our study will support development and investment in cost-effective strategies to minimize the iGBS burden and improve the chances for children to survive, thrive and reach their developmental and economic potential.
No data are associated with this article.
Proma Paul and Simon R. Procter are joint-first authors; Mark Jit and Joy E. Lawn are joint-senior authors.
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Competing Interests: See previous comments.
Reviewer Expertise: vaccine and drug development and introduction
Is the rationale for, and objectives of, the study clearly described?
Yes
Is the study design appropriate for the research question?
Yes
Are sufficient details of the methods provided to allow replication by others?
Partly
Are the datasets clearly presented in a useable and accessible format?
Yes
Competing Interests: I am in receipt of grant funding from the Bill & Melinda Gates Foundation but not for GBS research. I have collaborated with several members of this consortium but am not a member of the consortium. I confirm that these potential conflicts of interest did not affect my ability to write an objective and unbiased review of the article.
Reviewer Expertise: My interests span the basic biology, epidemiology, genomics and prevention of a range of mucosal pathogens including GBS.
Is the rationale for, and objectives of, the study clearly described?
Yes
Is the study design appropriate for the research question?
Partly
Are sufficient details of the methods provided to allow replication by others?
Yes
Are the datasets clearly presented in a useable and accessible format?
Yes
Competing Interests: No competing interests were disclosed.
Reviewer Expertise: Neonatology, microbiology, infectious diseases
Is the rationale for, and objectives of, the study clearly described?
Yes
Is the study design appropriate for the research question?
Partly
Are sufficient details of the methods provided to allow replication by others?
Yes
Are the datasets clearly presented in a useable and accessible format?
Yes
Competing Interests: PATH receives funding from BMGF in this area. The reviewer is a WHO PDVAC member
Reviewer Expertise: vaccine and drug development and introduction
Alongside their report, reviewers assign a status to the article:
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Version 1 23 Sep 20 |
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Provide sufficient details of any financial or non-financial competing interests to enable users to assess whether your comments might lead a reasonable person to question your impartiality. Consider the following examples, but note that this is not an exhaustive list:
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