Evaluation of the diagnostic performance of physician lung ultrasound versus chest radiography for pneumonia diagnosis in a peri-urban South African cohort

BACKGROUND

Lung ultrasound (US), which is radiation-free and cheaper than chest radiography (CXR), may be a useful modality for the diagnosis of pediatric pneumonia, but there are limited data from low- and middle-income countries.

OBJECTIVES

The aim of this study was to evaluate the diagnostic performance of non-radiologist, physician-performed lung US compared to CXR for pneumonia in children in a resource-constrained, African setting.

MATERIALS AND METHODS

Children under 5 years of age enrolled in a South African birth cohort study, the Drakenstein Child Health Study, who presented with clinically defined pneumonia and had a CXR performed also had a  lung US performed by a study doctor. Each modality was reported by two readers, using standardized methodology. Agreement between modalities, accuracy (sensitivity and specificity) of lung US and inter-rater agreement were assessed. Either consolidation or any abnormality (consolidation or interstitial picture) was considered as endpoints. In the 98 included cases (median age: 7.2 months; 53% male; 69% hospitalized), prevalence was 37% vs. 39% for consolidation and 52% vs. 76% for any abnormality on lung US and CXR, respectively. Agreement between modalities was poor for consolidation (observed agreement=61%, Kappa=0.18, 95% confidence interval [95% CI]: - 0.02 to 0.37) and for any abnormality (observed agreement=56%, Kappa=0.10, 95% CI: - 0.07 to 0.28). Using CXR as the reference standard, sensitivity of lung US was low for consolidation (47%, 95% CI: 31-64%) or any abnormality (5%, 95% CI: 43-67%), while specificity was moderate for consolidation (70%, 95% CI: 57-81%), but lower for any abnormality (58%, 95% CI: 37-78%). Overall inter-observer agreement of CXR was poor (Kappa=0.25, 95% CI: 0.11-0.37) and was significantly lower than the substantial agreement of lung US (Kappa=0.61, 95% CI: 0.50-0.75). Lung US demonstrated better agreement than CXR for all categories of findings, showing a significant difference for consolidation (Kappa=0.72, 95% CI: 0.58-0.86 vs. 0.32, 95% CI: 0.13-0.51).

CONCLUSION

Lung US identified consolidation with similar frequency to CXR, but there was poor agreement between modalities. The significantly higher inter-observer agreement of LUS compared to CXR supports the utilization of lung US by clinicians in a low-resource setting.

Clofazimine for the treatment of tuberculosis

Shorter (6-9 months), fully oral regimens containing new and repurposed drugs are now the first-choice option for the treatment of drug-resistant tuberculosis (DR-TB). Clofazimine, long used in the treatment of leprosy, is one such repurposed drug that has become a cornerstone of DR-TB treatment and ongoing trials are exploring novel, shorter clofazimine-containing regimens for drug-resistant as well as drug-susceptible tuberculosis. Clofazimine's repurposing was informed by evidence of potent activity against DR-TB strains in vitro and in mice and a treatment-shortening effect in DR-TB patients as part of a multidrug regimen. Clofazimine entered clinical use in the 1950s without the rigorous safety and pharmacokinetic evaluation which is part of modern drug development and current dosing is not evidence-based. Recent studies have begun to characterize clofazimine's exposure-response relationship for safety and efficacy in populations with TB. Despite being better tolerated than some other second-line TB drugs, the extent and impact of adverse effects including skin discolouration and cardiotoxicity are not well understood and together with emergent resistance, may undermine clofazimine use in DR-TB programmes. Furthermore, clofazimine's precise mechanism of action is not well established, as is the genetic basis of clofazimine resistance. In this narrative review, we present an overview of the evidence base underpinning the use and limitations of clofazimine as an antituberculosis drug and discuss advances in the understanding of clofazimine pharmacokinetics, toxicity, and resistance. The unusual pharmacokinetic properties of clofazimine and how these relate to its putative mechanism of action, antituberculosis activity, dosing considerations and adverse effects are highlighted. Finally, we discuss the development of novel riminophenazine analogues as antituberculosis drugs.

Association of Maternal and Child Anemia With Brain Structure in Early Life in South Africa

Importance

Anemia affects millions of pregnant women and their children worldwide, particularly in low- and middle-income countries. Although anemia in pregnancy is a well-described risk factor for cognitive development, the association with child brain structure is poorly understood.

Objective

To explore the association of anemia during pregnancy and postnatal child anemia with brain structure in early life.

Design, Setting, and Participants

This neuroimaging nested cohort study was embedded within the Drakenstein Child Health Study (DCHS), a population-based birth cohort in South Africa. Pregnant individuals were enrolled into the DCHS between 2012 and 2015 from 2 clinics in a periurban setting. Mother-child pairs were assessed prospectively; follow-up is ongoing. A subgroup of children had brain magnetic resonance imaging (MRI) at age 2 to 3 years from 2015 to 2018. This study focused on the 147 pairs with structural neuroimaging and available hemoglobin data. Data analyses were conducted in 2021 and 2022.

Exposures

Mothers had hemoglobin measurements during pregnancy, and a subgroup of children had hemoglobin measurements during early life. Anemia was classified as hemoglobin levels less than 11 g/dL based on World Health Organization guidelines; children younger than 6 months were classified using local guidelines.

Main Outcomes and Measures

Child brain volumes of global, subcortical, and corpus callosum structures were quantified using T1-weighted MRI. Linear regression models were used to analyze the associations between maternal and child anemia with child brain volumes, accounting for potential confounders.

Results

Of 147 children (mean [SD] age at MRI, 34 [2] months; 83 [56.5%] male) with high-resolution MRI scans, prevalence of maternal anemia in pregnancy was 31.3% (46 of 147; median [IQR] gestation of measurement: 13 [9-20] weeks). Maternal anemia during pregnancy was significantly associated with smaller volumes of the child caudate bilaterally (adjusted percentage difference, -5.30% [95% CI, -7.01 to -3.59]), putamen (left hemisphere: -4.33% [95% CI, -5.74 to -2.92]), and corpus callosum (-7.75% [95% CI, -11.24 to -4.26]). Furthermore, antenatal maternal hemoglobin levels were also associated with brain volumes in the caudate (left hemisphere: standardized β = 0.15 [95% CI, 0.02 to 0.28]; right hemisphere: β = 0.15 [95% CI, 0.02 to 0.27]), putamen left hemisphere (β = 0.21 [95% CI, 0.07 to 0.35]), and corpus callosum (β = 0.24 [95% CI, 0.09 to 0.39]). Prevalence of child anemia was 52.5% (42 of 80; median [IQR] age of measurement: 8.0 [2.7 to 14.8] months). Child anemia was not associated with brain volumes, nor did it mediate the association of maternal anemia during pregnancy with brain volumes.

Conclusions and Relevance

In this cohort study, anemia in pregnancy was associated with altered child brain structural development. Given the high prevalence of antenatal maternal anemia worldwide, these findings suggest that optimizing interventions during pregnancy may improve child brain outcomes.

A Longitudinal Study of the Epidemiology of Seasonal Coronaviruses in an African Birth Cohort

BACKGROUND

Since non-epidemic, seasonal human coronaviruses (sHCoV) commonly infect children, an improved understanding of the epidemiology of these infections may offer insights into the context of severe acute respiratory syndrome (SARS)-CoV-2. We investigated the epidemiology of sHCoV infection during the first year of life, including risk factors and association with lower respiratory tract infection (LRTI).

METHODS

We conducted a nested case-control study of infants enrolled in a birth cohort near Cape Town, South Africa, from 2012 to 2015. LRTI surveillance was implemented, and nasopharyngeal swabs were collected fortnightly over infancy. Quantitative PCR detected respiratory pathogens, including coronaviruses-229E, -NL63, -OC43, and -HKU1. Swabs were tested from infants at the time of LRTI and from the 90 days prior as well as from age-matched control infants from the cohort over the equivalent period.

RESULTS

In total, 885 infants were included, among whom 464 LRTI events occurred. Of the 4751 samples tested for sHCoV, 9% tested positive, with HCoV-NL63 the most common. Seasonal HCoV detection was associated with LRTI; this association was strongest for coronavirus-OC43, which was also found in all sHCoV-associated hospitalizations. Birth in winter was associated with sHCoV-LRTI, but there were no clear seasonal differences in detection. Co-detection of Streptococcus pneumoniae was weakly associated with sHCoV-LRTI (odds ratio: 1.8; 95% confidence interval: 0.9-3.6); detection of other respiratory viruses or bacteria was not associated with sHCoV status.

CONCLUSIONS

Seasonal HCoV infections were common and associated with LRTI, particularly sHCoV-OC43, which is most closely related to the SARS group of coronaviruses. Interactions of coronaviruses with bacteria in the pathogenesis of LRTI require further study.

Early-life respiratory syncytial virus lower respiratory tract infection in a South African birth cohort: epidemiology and effect on lung health

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infection (LRTI) in children. Early-life RSV LRTI might affect long-term health but there are few data from low-income and middle-income countries. We investigated the epidemiology and effect of early-life RSV LRTI on lung health in a South African birth cohort.

METHODS

We conducted the Drakenstein Child Health Study (DCHS), an ongoing birth cohort longitudinal study in the Western Cape province, South Africa. We enrolled pregnant women aged 18 years or older during their second trimester of pregnancy at two public health clinics. We followed up study children from birth to 2 years. The primary outcome of the study was LRTI and RSV LRTI. LRTI and wheezing episodes were identified through active surveillance; respiratory samples were tested for RSV and other pathogens. Wheezing was longitudinally identified by caregiver report and ascertainment at health facilities. Lung function was measured from 6 weeks to 2 years. We analysed the associations between RSV LRTI and subsequent LRTI, wheezing, and lung function using generalised estimating equations and mixed-effects linear regression.

FINDINGS

We enrolled 1137 mothers between March 5, 2012, and March 31, 2015. Among their 1143 infants, accruing 2093 child-years of follow-up, there were 851 cases of LRTI (incidence 0·41 episodes per child-year, 95% CI 0·38-0·43). Admission to hospital owing to LRTI occurred in 169 (20%) cases (incidence 0·08 episodes per child-year, 0·07-0·09), with a case-fatality ratio of 0·5%. RSV was detected in 164 (21%) of 785 LRTI events with a specimen available for qPCR, an incidence of 0·08 episodes per child-year (0·07-0·09); highest at age 0-6 months (0·15 episodes per child-year, 0·12-0·19). Children with a first RSV LRTI were three times as likely to develop recurrent LRTI compared with those with non-RSV LRTI (0·32 [0·22-0·48] vs 0·10 [0·07- 0·16] episodes per child-year; p<0·0001), particularly following hospitalised RSV LRTI. RSV LRTI and hospitalisation for all-cause LRTI were independently associated with recurrent wheezing (adjusted incident rate ratio 1·41, 95% CI 1·25-1·59, for RSV LRTI and 1·48, 1·30-1·68, for hospitalisation). LRTI or recurrent LRTI was associated with impaired lung function, but a similar outcome was observed following RSV LRTI or non-RSV LRTI. All-cause LRTI was associated with an average 3% higher respiratory rate (95% CI 0·01-0·06; p=0·013) and lower compliance (-0·1, -0·18 to 0·02) at 2 years compared with no LRTI. Recurrent LRTI was associated with further increased respiratory rate (0·01, 0·001-0·02), resistance (0·77 hPa s L-1, 0·07-1·47), and lower compliance (-0·6 mL hPa-1, -0·09 to -0·02) with each additional event.

INTERPRETATION

RSV LRTI was common in young infants and associated with recurrent LRTI, particularly after hospitalised RSV. Hospitalisation for all-cause LRTI, especially for RSV-LRTI, was associated with recurrent wheezing. Impairments in lung function followed LRTI or recurrent episodes, but were not specific to RSV. New preventive strategies for RSV might have an effect on long-term lung health.

FUNDING

Bill & Melinda Gates Foundation; South African Medical Research Council; National Research Foundation South Africa; National Institutes of Health, Human Heredity and Health in Africa; Wellcome Trust.

Implementation of prevention of mother-to-child transmission (PMTCT) in South Africa: outcomes from a population-based birth cohort study in Paarl, Western Cape

OBJECTIVES

The coverage of prevention of mother-to-child transmission (PMTCT) services in South Africa is variable. Identifying gaps in the implementation of these services is necessary to isolate steps needed to further reduce paediatric infections and eliminate transmission.

SETTING

Two primary care clinics in Paarl, South Africa.

PARTICIPANTS

1225 pregnant women; inclusion criteria were 18 years or older, clinic attendance and remaining in area for at least 1 year.

METHODS

Data were collected through the Drakenstein Child Health Study, a population-based birth cohort in a periurban area of the Western Cape, South Africa. A combination of clinic records, hospital records, national database searches and maternal self-report were collected during the study.

RESULTS

Of the 1225 mothers enrolled in the cohort between 2012 and 2015, 260 (21%) were confirmed HIV infected antenatally and 1 mother tested positive in the postnatal period. Of those with documentation (n=250/260, 96%), the majority (99%) received antiretroviral prophylaxis or therapy (ART) before labour; however, there was a high rate of defaulting from ART noted during pregnancy (20%). All HIV-exposed infants with data received antiretroviral prophylaxis, 35% were exclusively breast fed until 6 weeks and 16% for 6 months. There were two cases of infant HIV infection (0.8%) who were initiated on ART but had complicated histories.

CONCLUSION

Despite the low transmission rate in this cohort, reaching elimination will require further work, and this study illustrates several areas to improve implementation of PMTCT services and reduce paediatric infections including retesting at-risk HIV-negative mothers through the duration of breast feeding, infant HIV testing at any admission in addition to routine testing and improved counselling to prevent defaulting from treatment. Better data surveillance systems are essential for determining the implementation of PMTCT guidelines.

Neurodevelopment of HIV-exposed uninfected children in South Africa: outcomes from an observational birth cohort study

BACKGROUND

HIV infection is known to cause developmental delay, but the effects of HIV exposure without infection during pregnancy on child development are unclear. We compared the neurodevelopmental outcomes of HIV-exposed uninfected and HIV-unexposed children during their first 2 years of life.

METHODS

Pregnant women (>18 years of age) at 20-28 weeks' gestation were enrolled into the Drakenstein Child Health cohort study while attending routine antenatal appointments at one of two peri-urban community-based clinics in Paarl, South Africa. Livebirths born to enrolled women during follow-up were included in the birth cohort. Mothers and infants received antenatal and postnatal HIV testing and antiretroviral therapy per local guidelines. Developmental assessments on the Bayley Scales of Infant and Toddler Development, third edition (BSID-III), were done in a subgroup of infants at 6 months of age, and in the full cohort at 24 months of age, with assessors masked to HIV exposure status. Mean raw scores and the proportions of children categorised as having a delay (scores <-2 SDs from the reference mean) on BSID-III were compared between HIV-exposed uninfected and HIV-unexposed children.

FINDINGS

1225 women were enrolled between March 5, 2012, and March 31, 2015. Of 1143 livebirths, 1065 (93%) children were in follow-up at 6 months and 1000 (87%) at 24 months. Two children were diagnosed with HIV infection between birth and 24-month follow-up and were excluded from the analysis. BSID-III assessments were done in 260 (24%) randomly selected children (61 HIV-exposed uninfected, 199 HIV-unexposed) at 6 months and in 732 (73%) children (168 HIV-exposed uninfected, 564 HIV-unexposed) at 24 months. All HIV-exposed uninfected children were exposed to antiretrovirals (88% to maternal triple antiretroviral therapy). BSID-III outcomes did not significantly differ between HIV-exposed uninfected and HIV-unexposed children at 6 months. At 24 months, HIV-exposed uninfected children scored lower than HIV-unexposed for receptive language (adjusted mean difference -1·03 [95% CI -1·69 to -0·37]) and expressive language (-1·17 [-2·09 to -0·24]), whereas adjusted differences in cognitive (-0·45 [-1·32 to 0·43]), fine motor (0·09 [-0·49 to 0·66]), and gross motor (-0·41 [-1·09 to 0·27]) domain scores between groups were not significant. Correspondingly, the proportions of HIV-exposed uninfected children with developmental delay were higher than those of HIV-unexposed children for receptive language (adjusted odds ratio 1·96 [95% CI 1·09 to 3·52]) and expressive language (2·14 [1·11 to 4·15]).

INTERPRETATION

Uninfected children exposed to maternal HIV infection and antiretroviral therapy have increased odds of receptive and expressive language delays at 2 years of age. Further long-term work is needed to understand developmental outcomes of HIV-exposed uninfected children, especially in regions such as sub-Saharan Africa that have a high prevalence of HIV exposure among children.

FUNDING

Bill & Melinda Gates Foundation, SA Medical Research Council, Wellcome Trust.

Lower Respiratory Tract Infections in Children in a Well-vaccinated South African Birth Cohort: Spectrum of Disease and Risk Factors

Background

Childhood lower respiratory tract infections (LRTIs) cause substantial morbidity and under-5 child mortality. The epidemiology of LRTI is changing in low- and middle-income countries with expanding access to conjugate vaccines, yet there are few data on the incidence and risk factors for LRTI in these settings.

Methods

A prospective birth cohort enrolled mother–infant pairs in 2 communities near Cape Town, South Africa. Active surveillance for LRTI was performed for the first 2 years of life over 4 respiratory seasons. Comprehensive data collection of risk factors was done through 2 years of life. World Health Organization definitions were used to classify clinical LRTI and chest radiographs.

Results

From March 2012 to February 2017, 1143 children were enrolled and followed until 2 years of age. Thirty-two percent of children were exposed to antenatal maternal smoking; 15% were born at low birth weights. Seven hundred ninety-five LRTI events occurred in 429 children by February 2017; incidence of LRTI was 0.51 and 0.25 episodes per child-year in the first and second years of life, respectively. Human immunodeficiency virus (HIV)–exposed, uninfected infants (vs HIV-unexposed infants) were at increased risk of hospitalized LRTI in the first 6 months of life. In regression models, male sex, low birth weight, and maternal smoking were independent risk factors for both ambulatory and hospitalized LRTI; delayed or incomplete vaccination was associated with hospitalized LRTI.

Conclusions

LRTI incidence was high in the first year of life, with substantial morbidity. Strategies to ameliorate harmful exposures are needed to reduce LRTI burden in vulnerable populations.

Intra-breath measures of respiratory mechanics in healthy African infants detect risk of respiratory illness in early life

Lower respiratory tract illness (LRTI) is a leading cause of mortality and morbidity in children. Sensitive and noninvasive infant lung function techniques are needed to measure risk for and impact of LRTI on lung health. The objective of this study was to investigate whether lung function derived from the intra-breath forced oscillation technique (FOT) was able to identify healthy infants at risk of LRTI in the first year of life.

Lung function was measured with the novel intra-breath FOT, in 6-week-old infants in a South African birth cohort (Drakenstein Child Health Study). LRTI during the first year was confirmed by study staff. The association between baseline lung function and LRTI was assessed with logistic regression and odds ratios determined using optimal cut-off values.

Of the 627 healthy infants with successful lung function testing, 161 (24%) had 238 LRTI episodes subsequently during the first year. Volume dependence of respiratory resistance (ΔR) and reactance (ΔX) was associated with LRTI. The predictive value was stronger if LRTI was recurrent (n=50 (31%): OR 2.5, ΔX), required hospitalisation (n=38 (16%): OR 5.4, ΔR) or was associated with wheeze (n=87 (37%): OR 3.9, ΔX).

Intra-breath FOT can identify healthy infants at risk of developing LRTI, wheezing or severe illness in the first year of life.

Novel measurements of respiratory mechanics are feasible in infants in a community setting and able to detect changes in lung function in healthy infants associated with increased risk of subsequent LRTI in infancyhttp://ow.ly/IUKk30mCfi3

Lung ultrasound for the diagnosis of community-acquired pneumonia in children

Ultrasound (US) has been proposed as an alternative first-line imaging modality to diagnose community-acquired pneumonia in children. Lung US has the potential benefits over chest radiography of being radiation free, subject to fewer regulatory requirements, relatively lower cost and with immediate bedside availability of results. However, the uptake of lung US into clinical practice has been slow and it is not yet included in clinical guidelines for community-acquired pneumonia in children. The aim of this review is to give an overview of the equipment and techniques used to perform lung US in children with suspected pneumonia and the interpretation of relevant sonographic findings. We also summarise the current evidence of diagnostic accuracy and reliability of lung US compared to alternative imaging modalities in children and critically consider the strengths and limitations of lung US for use in children presenting with suspected community-acquired pneumonia.