An evaluation of chest X-ray in the context of community-based screening of child tuberculosis contacts

Comparison of chest radiographs against minimum intensity projection reconstruction computed tomography scans for detection of airway stenosis in children with lymphobronchial tuberculosis

BACKGROUND

Ideally, suspected airway compression in symptomatic children with lymphobronchial tuberculosis (TB) would be diagnosed using modern computed tomography (CT) assisted by coronal minimum intensity projection (MinIP) reconstructions. However, in TB-endemic regions with limited resources, practitioners rely on conventional radiography for diagnosing TB and its complications. Furthermore, airway compression detected on conventional radiographs would upgrade a patient into the severe category according to the new World Health Organization guidelines, precluding the patient from shorter treatment protocols. The accuracy of conventional radiographs in the context of detecting airway compression in children with TB has not been specifically evaluated against an imaging gold standard.

OBJECTIVE

We aimed to compare frontal chest radiographs against thick-slab angled coronal CT MinIP in identifying airway stenosis at ten specific sites and to determine observer agreement between the modalities regarding the degree of stenosis.

MATERIALS AND METHODS

This retrospective cross-sectional study compared chest radiographs with standardized angled coronal CT MinIP in children with symptomatic lymphobronchial TB at ten predetermined airway locations. Chest radiographs were evaluated by one pediatric radiologist and CT MinIP reconstructions were independently interpreted by three readers. Sensitivity and specificity were calculated using CT MinIP as the gold standard. Stenosis was graded as 1 for mild (1-50%), 2 for moderate (51-75%), 3a for severe (76-99%), and 3b for total occlusion (100%). Agreement between the two modalities regarding severity of stenosis was calculated using the kappa coefficient for each affected site.

RESULTS

A total of 37 patients were included in the study. The median age of patients was 14.3 months (interquartile range 8.0-23.2). Three hundred and seventy individual bronchi (10 from each of the 37 patients) were evaluated for stenosis. Chest radiographs showed that 31 out of 37 (84%) patients had stenosis in at least one of ten evaluated sites, most commonly the left main bronchus and bronchus intermedius, and this was confirmed via CT MinIP. The gold standard (CT MinIP) demonstrated stenosis in at least one of ten sites in all 37 patients (100%). Left main bronchus stenosis was detected by chest radiography with a 92.9% sensitivity and 100% specificity. Sensitivity and specificity for bronchus intermedius stenosis were 80% and 75%, respectively. There was substantial agreement for grade of stenosis between chest radiographs and CT (kappa=0.67) for the left main bronchus and moderate agreement (kappa=0.58) for the bronchus intermedius. Severe stenosis was found in 78 bronchi on CT compared to 32 bronchi (Grade 3a: 9, Grade 3b: 23) on chest radiographs.

CONCLUSION

The diagnosis of pulmonary TB in children continues to rely heavily on imaging, and we have shown that in young children, chest radiographs had a high sensitivity and specificity for detecting airway stenosis at certain anatomical sites, when adequately visualized, resulting from tuberculous lymph node compression at left main bronchus and bronchus intermedius. For most sites, the interobserver agreement was poor. Stenosis of the left main bronchus and bronchus intermedius should be the focus of chest radiograph interpretation and can assist both diagnosis and classification of patients for treatment.

Frequency of abnormal findings on chest radiograph after positive PPD in children and adolescents in an urban setting in the United States

BACKGROUND

Chest radiographs (CXR) for tuberculosis (TB) screening in children are valuable in high-burden settings. However, less certain in low prevalence contexts. In the United States, positive PPD is sufficient to treat for "latent" TB, or TB infection in asymptomatic patients.

OBJECTIVE

We sought to determine frequency of abnormal CXR findings after a positive purified protein derivative (PPD) test at a tertiary pediatric center in the United States.

METHOD

A retrospective evaluation was conducted of patients (0-18 years) with a CXR after a positive PPD (e.g., known exposure, employment, migratory requirements or before immunosuppression) between 2011 and 2021. Clinical information, demographics, and reason for PPD were recorded from health record. CXRs were evaluated using initial report and by a pediatric radiologist with special interest in TB and 8 years of experience.

RESULT

Of 485 patients, median [interquartile range (IQR)] age 8.5[3.3-14.4], abnormal CXRs were described in 5 (1%). Most common reasons for PPD included: close contact with someone with TB or with high risk for TB. Most patients 373 (76.9%) received treatment for latent TB, and 111 (22.9%) no treatment. One patient (0.2%) received treatment for active disease. Radiographic findings included isolated lymphadenopathy (n = 2), consolidation (n = 1), pleural fluid/thickening (n = 1) and a patient with lymphadenopathy and a calcified nodule (n = 1).

CONCLUSION

In our experience, prevalence of chest radiographs findings for patients with positive PPD was very low. Moreover, no cases of severe disease were seen and those with abnormal findings would not merit treatment change under current WHO guidelines.

Artificial Intelligence in Paediatric Tuberculosis

Tuberculosis (TB) continues to be a leading cause of death in children despite global efforts focused on early diagnosis and interventions to limit the spread of the disease. This challenge has been made more complex in the context of the coronavirus pandemic, which has disrupted the "End TB Strategy" and framework set out by the World Health Organization (WHO). Since the inception of artificial intelligence (AI) more than 60 years ago, the interest in AI has risen and more recently we have seen the emergence of multiple real-world applications, many of which relate to medical imaging. Nonetheless, real-world AI applications and clinical studies are limited in the niche area of paediatric imaging. This review article will focus on how AI, or more specifically deep learning, can be applied to TB diagnosis and management in children. We describe how deep learning can be utilised in chest imaging to provide computer-assisted diagnosis to augment workflow and screening efforts. We also review examples of recent AI applications for TB screening in resource constrained environments and we explore some of the challenges and the future directions of AI in paediatric TB.

Imaging recommendations and algorithms for pediatric tuberculosis: part 1-thoracic tuberculosis

Tuberculosis (TB) remains a global health problem and is the second leading cause of death from a single infectious agent, behind the novel coronavirus disease of 2019. Children are amongst the most vulnerable groups affected by TB, and imaging manifestations are different in children when compared to adults. TB primarily involves the lungs and mediastinal lymph nodes. Clinical history, physical examination, laboratory examinations and various medical imaging tools are combined to establish the diagnosis. Even though chest radiography is the accepted initial radiological imaging modality for the evaluation of children with TB, this paper, the first of two parts, aims to discuss the advantages and limitations of the various medical imaging modalities and to provide recommendations on which is most appropriate for the initial diagnosis and assessment of possible complications of pulmonary TB in children. Practical, evidence-based imaging algorithms are also presented.

Testing and Scaling Interventions to Improve the Tuberculosis Infection Care Cascade

Tuberculosis (TB) preventive therapy (TPT) is increasingly recognized as the key to eliminating tuberculosis globally and is particularly critical for children with TB infection or who are in close contact with individuals with infectious TB. But many barriers currently impede successful scale-up to provide TPT to those at high risk of TB disease. The cascade of care in TB infection (and the related contact management cascade) is a conceptual framework to evaluate and improve the care of persons who are potential candidates for TPT. This review summarizes recent literature on barriers and solutions in the TB infection care cascade, focusing on children in both high- and low-burden settings, and drawing from studies on children and adults. Identifying and closing gaps in the care cascade will require the implementation of tools that are new (e.g. computer-assisted radiography) and old (e.g. efficient contact tracing), and will be aided by innovative implementation study designs, quality improvement methods, and shared clinical practice with primary care providers.

The Contribution of Chest Radiography to the Clinical Management of Children Exposed to Tuberculosis

Rationale: Although World Health Organization guidelines emphasize contact investigation for tuberculosis (TB)-exposed children, data that support chest radiography as a useful tool are lacking. Objectives: We evaluated the diagnostic and prognostic information of chest radiography in children exposed to TB and measured the efficacy of isoniazid preventive therapy (IPT) in those with relevant radiographic abnormalities. Methods: Between September 2009 and August 2012, we enrolled 4,468 TB-exposed children who were screened by tuberculin skin testing, symptom assessment, and chest radiography. Those negative for TB disease were followed for 1 year for the occurrence of new TB diagnoses. We assessed the protective efficacy of IPT in children with and without abnormal chest radiographs. Measurements and Main Results: Compared with asymptomatic children with normal chest films, asymptomatic children with abnormal radiographs were 25.1-fold more likely to have coprevalent TB (95% confidence interval [CI], 1.02-613.76) and 26.7-fold more likely to be diagnosed with incident TB disease during follow-up (95% CI, 10.44-68.30). Among the 29 symptom-negative and CXR-abnormal child contacts, 20% (3/15) of the isoniazid recipients developed incident TB, compared with 57% (8/14) of those who did not receive IPT (82% IPT efficacy). Conclusions: Our results strongly support the use of chest radiography as a routine screening tool for the evaluation of child TB contacts, which is readily available. Radiographic abnormalities not usually considered suggestive of TB may indicate incipient or subclinical disease, although TB preventive treatment is adequate in most cases.

Reproducibility of a protocol for standardized reading of chest X-rays of children household contact of patients with tuberculosis

BACKGROUND

The interpretation of the chest radiograph may vary because it depends on the reader and due to the non-specificity of findings in tuberculosis (TB). We aim to assess the reproducibility of a standardized chest radiograph reading protocol in contacts of patients with pulmonary TB under the 5 years of age.

METHODS

Descriptive, cross-sectional study with children under the age of five, household contacts of patients with confirmed pulmonary TB from Medellín, Bello and Itagüí (Colombia) between Jan-01-2015 and May-31-2016. Standardized reading protocol: two radiologists, blinded independent reading, use of template (Dr. Andronikou design) in case of disagreement a third reading was performed. Kappa coefficient for intra and inter observer agreement, and prevalence ratio were estimated of sociodemographic characteristics, TB exposure and interpretation of chest X-ray.

RESULTS

From 278 children, standardized reading found 255 (91.7%) normal X-rays, 10 (3.6%) consistent with TB, and 13 (4.7%) other alterations. Global agreement was 91.3% (Kappa = 0.51). Inter-observer agreement between readers 1-2 was 90.0% (Kappa = 0.59) and 1-3 93.2% (Kappa = 0.59). Intra-observer agreement for reader 1 was 95.5% (Kappa = 0.86), 2 84.0% (Kappa = 0.51), and 3 94.7% (Kappa = 0.68). Greater inter-observer disagreement was between readers 1-2 for soft tissue density suggestive of adenopathy (4.6%), airspace opacification (1.17%) and pleural effusion (0.58%); between readers 1-3 for soft tissue density suggestive of adenopathy (4.2%), opacification of airspace (2.5%) and cavities (0.8%).

CONCLUSIONS

Chest radiographs are an affordable tool that contributes to the diagnosis of TB, so having a standardized reading protocol showed good agreement and improves the reproducibility of radiograph interpretation.

Diagnostic Challenges in Childhood Pulmonary Tuberculosis-Optimizing the Clinical Approach

The management of childhood tuberculosis (TB) is hampered by the low sensitivity and limited accessibility of microbiological testing. Optimizing clinical approaches is therefore critical to close the persistent gaps in TB case detection and prevention necessary to realize the child mortality targets of the End TB Strategy. In this review, we provide practical guidance summarizing the evidence and guidelines describing the use of symptoms and signs in decision making for children being evaluated for either TB preventive treatment (TPT) or TB disease treatment in high-TB incidence settings. Among at-risk children being evaluated for TPT, a symptom screen may be used to differentiate children who require further investigation for TB disease before receiving TPT. For symptomatic children being investigated for TB disease, an algorithmic approach can inform which children should receive TB treatment, even in the absence of imaging or microbiological confirmation. Though clinical approaches have limitations in accuracy, they are readily available and can provide valuable guidance for decision making in resource-limited settings to increase treatment access. We discuss the trade-offs in using them to make TB treatment decisions.

Symptom-based Screening Versus Chest Radiography for TB Child Contacts: A Systematic Review and Meta-analysis

BACKGROUND

Accessibility to chest radiography remains a major challenge in high burden and low-income countries. The World Health Organization (WHO) guidelines acknowledge that for child contacts under 5 years, a negative symptom-based screening is sufficient to exclude active tuberculosis (TB), but in child contacts older than 5 years, a chest radiograph should be considered. We performed a systematic review and meta-analysis to assess the performance of symptom-based screening compared with chest radiography in household contacts under 15 years in low-income and middle-income countries.

METHODS

Screening articles published prior 1 October 2020 and data extraction were performed by 2 independent reviewers. The primary outcome was the concordance between symptom screening and chest radiography using the prevalence adjusted bias adjusted kappa coefficient (PABAK) and the proportion of asymptomatic children with negative chest radiography. The analysis was stratified by age group.

RESULTS

Of 639 identified articles, 10 were included. PABAK varied between 0.09 and 0.97 and between 0.22 and 0.98, in children less than 5 years and 5-14 years, respectively. The pooled proportion of children with both non-TB suggestive symptoms and chest radiography findings was 98.7% (96.9-99.8) in children less than 5 years and 98.1% (93.8-100) in children of age 5-14 years.

CONCLUSIONS

Despite low concordance between symptom-based screening and chest radiography, most children without TB suggestive symptoms did not have chest radiography findings suggestive of TB. These results suggest that a negative symptom screening is sufficient to rule out active TB, supporting the WHO recommendation to use symptom-based screening alone when chest radiography is not available.

Screening tests for active pulmonary tuberculosis in children

BACKGROUND

Globally, children under 15 years represent approximately 12% of new tuberculosis cases, but 16% of the estimated 1.4 million deaths. This higher share of mortality highlights the urgent need to develop strategies to improve case detection in this age group and identify children without tuberculosis disease who should be considered for tuberculosis preventive treatment. One such strategy is systematic screening for tuberculosis in high-risk groups.

OBJECTIVES

To estimate the sensitivity and specificity of the presence of one or more tuberculosis symptoms, or symptom combinations; chest radiography (CXR); Xpert MTB/RIF; Xpert Ultra; and combinations of these as screening tests for detecting active pulmonary childhood tuberculosis in the following groups. - Tuberculosis contacts, including household contacts, school contacts, and other close contacts of a person with infectious tuberculosis. - Children living with HIV. - Children with pneumonia. - Other risk groups (e.g. children with a history of previous tuberculosis, malnourished children). - Children in the general population in high tuberculosis burden settings.

SEARCH METHODS

We searched six databases, including the Cochrane Central Register of Controlled Trials, MEDLINE, and Embase, on 14 February 2020 without language restrictions and contacted researchers in the field.

SELECTION CRITERIA

Cross-sectional and cohort studies where at least 75% of children were aged under 15 years. Studies were eligible if conducted for screening rather than diagnosing tuberculosis. Reference standards were microbiological (MRS) and composite reference standard (CRS), which may incorporate symptoms and CXR.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed study quality using QUADAS-2. We consolidated symptom screens across included studies into groups that used similar combinations of symptoms as follows: one or more of cough, fever, or poor weight gain and one or more of cough, fever, or decreased playfulness. For combination of symptoms, a positive screen was the presence of one or more than one symptom. We used a bivariate model to estimate pooled sensitivity and specificity with 95% confidence intervals (CIs) and performed analyses separately by reference standard. We assessed certainty of evidence using GRADE.

MAIN RESULTS

Nineteen studies assessed the following screens: one symptom (15 studies, 10,097 participants); combinations of symptoms (12 studies, 29,889 participants); CXR (10 studies, 7146 participants); and Xpert MTB/RIF (2 studies, 787 participants). Several studies assessed more than one screening test. No studies assessed Xpert Ultra. For 16 studies (84%), risk of bias for the reference standard domain was unclear owing to concern about incorporation bias. Across other quality domains, risk of bias was generally low. Symptom screen (verified by CRS) One or more of cough, fever, or poor weight gain in tuberculosis contacts (4 studies, tuberculosis prevalence 2% to 13%): pooled sensitivity was 89% (95% CI 52% to 98%; 113 participants; low-certainty evidence) and pooled specificity was 69% (95% CI 51% to 83%; 2582 participants; low-certainty evidence). Of 1000 children where 50 have pulmonary tuberculosis, 339 would be screen-positive, of whom 294 (87%) would not have pulmonary tuberculosis (false positives); 661 would be screen-negative, of whom five (1%) would have pulmonary tuberculosis (false negatives). One or more of cough, fever, or decreased playfulness in children aged under five years, inpatient or outpatient (3 studies, tuberculosis prevalence 3% to 13%): sensitivity ranged from 64% to 76% (106 participants; moderate-certainty evidence) and specificity from 37% to 77% (2339 participants; low-certainty evidence). Of 1000 children where 50 have pulmonary tuberculosis, 251 to 636 would be screen-positive, of whom 219 to 598 (87% to 94%) would not have pulmonary tuberculosis; 364 to 749 would be screen-negative, of whom 12 to 18 (2% to 3%) would have pulmonary tuberculosis. One or more of cough, fever, poor weight gain, or tuberculosis close contact (World Health Organization four-symptom screen) in children living with HIV, outpatient (2 studies, tuberculosis prevalence 3% and 8%): pooled sensitivity was 61% (95% CI 58% to 64%; 1219 screens; moderate-certainty evidence) and pooled specificity was 94% (95% CI 86% to 98%; 201,916 screens; low-certainty evidence). Of 1000 symptom screens where 50 of the screens are on children with pulmonary tuberculosis, 88 would be screen-positive, of which 57 (65%) would be on children who do not have pulmonary tuberculosis; 912 would be screen-negative, of which 19 (2%) would be on children who have pulmonary tuberculosis. CXR (verified by CRS) CXR with any abnormality in tuberculosis contacts (8 studies, tuberculosis prevalence 2% to 25%): pooled sensitivity was 87% (95% CI 75% to 93%; 232 participants; low-certainty evidence) and pooled specificity was 99% (95% CI 68% to 100%; 3281 participants; low-certainty evidence). Of 1000 children, where 50 have pulmonary tuberculosis, 63 would be screen-positive, of whom 19 (30%) would not have pulmonary tuberculosis; 937 would be screen-negative, of whom 6 (1%) would have pulmonary tuberculosis. Xpert MTB/RIF (verified by MRS) Xpert MTB/RIF, inpatient or outpatient (2 studies, tuberculosis prevalence 1% and 4%): sensitivity was 43% and 100% (16 participants; very low-certainty evidence) and specificity was 99% and 100% (771 participants; moderate-certainty evidence). Of 1000 children, where 50 have pulmonary tuberculosis, 31 to 69 would be Xpert MTB/RIF-positive, of whom 9 to 19 (28% to 29%) would not have pulmonary tuberculosis; 969 to 931 would be Xpert MTB/RIF-negative, of whom 0 to 28 (0% to 3%) would have tuberculosis. Studies often assessed more symptoms than those included in the index test and symptom definitions varied. These differences complicated data aggregation and may have influenced accuracy estimates. Both symptoms and CXR formed part of the CRS (incorporation bias), which may have led to overestimation of sensitivity and specificity.

AUTHORS' CONCLUSIONS

We found that in children who are tuberculosis contacts or living with HIV, screening tests using symptoms or CXR may be useful, but our review is limited by design issues with the index test and incorporation bias in the reference standard. For Xpert MTB/RIF, we found insufficient evidence regarding screening accuracy. Prospective evaluations of screening tests for tuberculosis in children will help clarify their use. In the meantime, screening strategies need to be pragmatic to address the persistent gaps in prevention and case detection that exist in resource-limited settings.

Paediatric tuberculosis - new advances to close persistent gaps

Young children are most vulnerable to develop severe forms of tuberculosis (TB) and are over-represented among TB deaths. Almost all children estimated to have died from TB were never diagnosed or offered TB treatment. Improved access to TB preventive treatment (TPT) requires major upscaling of household contact investigation with allocation of adequate resources. Symptom-based screening is often discouraged in adults for fear of generating drug resistance, if TB cases are missed. However, the situation in vulnerable young children is different, as they present minimal risk of drug resistance generation. Further, the perceived need for additional diagnostic evaluation presents a major barrier to TPT access and underlies general reluctance to consider pragmatic decentralised models of care. Widespread roll-out of Xpert MTB/RIF Ultra® represents an opportunity for improved case detection in young children, but attaining full impact will require the use of non-sputum specimens. The new Fujifilm SILVAMP TB LAM® urine assay demonstrated good diagnostic accuracy in HIV-positive and malnourished children, but further validation is required. Given the limited accuracy of all available tests and the excellent tolerance of TB drugs in children, the global community may have to accept some over-treatment if we want to close the persistent case detection gap in young children.

Community intervention for child tuberculosis active contact investigation and management: study protocol for a parallel cluster randomized controlled trial

Background

There are major gaps in the management of pediatric tuberculosis (TB) contact investigation for rapid identification of active tuberculosis and initiation of preventive therapy. This study aims to evaluate the impact of a community-based intervention as compared to facility-based model for the management of children in contact with bacteriologically confirmed pulmonary TB adults in low-resource high-burden settings.

Methods/design

This multicenter parallel open-label cluster randomized controlled trial is composed of three phases: I, baseline phase in which retrospective data are collected, quality of data recording in facility registers is checked, and expected acceptability and feasibility of the intervention is assessed; II, intervention phase with enrolment of index cases and contact cases in either facility- or community-based models; and III, explanatory phase including endpoint data analysis, cost-effectiveness analysis, and post-intervention acceptability assessment by healthcare providers and beneficiaries. The study uses both quantitative and qualitative analysis methods. The community-based intervention includes identification and screening of all household contacts, referral of contacts with TB-suggestive symptoms to the facility for investigation, and household initiation of preventive therapy with follow-up of eligible child contacts by community healthcare workers, i.e., all young (< 5 years) child contacts or older (5–14 years) child contacts living with HIV, and with no evidence of TB disease. Twenty clusters representing TB diagnostic and treatment facilities with their catchment areas are randomized in a 1:1 ratio to either the community-based intervention arm or the facility-based standard of care arm in Cameroon and Uganda. Randomization was stratified by country and constrained on the number of index cases per cluster. The primary endpoint is the proportion of eligible child contacts who initiate and complete the preventive therapy. The sample size is of 1500 child contacts to identify a 10% difference between the arms with the assumption that 60% of children will complete the preventive therapy in the standard of care arm.

Discussion

This study will provide evidence of the impact of a community-based intervention on household child contact screening and management of TB preventive therapy in order to improve care and prevention of childhood TB in low-resource high-burden settings.

Trial registration

ClinicalTrials.gov NCT03832023. Registered on 6 February 2019

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05124-9.

Reliability of chest radiograph interpretation for pulmonary tuberculosis in the screening of childhood TB contacts and migrant children in the UK

AIM

To determine interobserver agreement between paediatric radiologists interpreting tuberculosis (TB) screening chest radiographs (CXR) in children in the UK, and the TB detection rate.

MATERIALS AND METHODS

A retrospective review was undertaken of electronic request, notes, and CXRs (>7 years) in children exposed to an infectious case of TB and new entrants to the UK, at a tertiary children's hospital. Included were those with positive Mantoux/interferon gamma release assay (IGRA), positive culture, or high clinical suspicion of TB. CXR reports were categorised as normal, abnormal without features of TB, or abnormal with features of pulmonary TB. Three paediatric radiologists from a dedicated paediatric radiology department evaluated available CXRs, aware of the TB screening indication, using a published CXR reporting tool and blinded to the initial CXR report and to each other. A majority decision was collated, and considered lymphadenopathy and miliary nodules as diagnostic of primary TB. Interobserver agreement was calculated using Cohen's kappa.

RESULTS

One hundred and forty-eight children underwent TB screening with a CXR. One hundred and twenty-five had available CXR reports and case notes, which indicated 20/125 (16%) had CXR features of TB. One hundred and twenty-one of the 125 had CXRs available to for panel review. Twenty of these 121 (17%) yielded a majority decision of pulmonary TB. Inter-reader agreement was moderate in all aspects (kappa 0.4-0.6).

CONCLUSION

The high percentage of pulmonary TB on CXR (16% original reports; 17% by panel review) suggests that it is worthwhile investigating childhood TB contacts; however, the routine use and recommendation for CXR is questionable because of only moderate interpretation reliability (kappa 0.5), even by experts.

Advanced imaging tools for childhood tuberculosis: potential applications and research needs

Tuberculosis is the leading cause of death globally that is due to a single pathogen, and up to a fifth of patients with tuberculosis in high-incidence countries are children younger than 16 years. Unfortunately, the diagnosis of childhood tuberculosis is challenging because the disease is often paucibacillary and it is difficult to obtain suitable specimens, causing poor sensitivity of currently available pathogen-based tests. Chest radiography is important for diagnostic evaluations because it detects abnormalities consistent with childhood tuberculosis, but several limitations exist in the interpretation of such results. Therefore, other imaging methods need to be systematically evaluated in children with tuberculosis, although current data suggest that when available, cross-sectional imaging, such as CT, should be considered in the diagnostic evaluation for tuberculosis in a symptomatic child. Additionally, much of the understanding of childhood tuberculosis stems from clinical specimens that might not accurately represent the lesional biology at infection sites. By providing non-invasive measures of lesional biology, advanced imaging tools could enhance the understanding of basic biology and improve on the poor sensitivity of current pathogen detection systems. Finally, there are key knowledge gaps regarding the use of imaging tools for childhood tuberculosis that we outlined in this Personal View, in conjunction with a proposed roadmap for future research.

An Assessment of Inter-Observer Agreement in Water Source Classification and Sanitary Risk Observations

Sanitary risk inspection, an observation protocol for identifying contamination hazards around water sources, is promoted for managing rural water supply safety. However, it is unclear how far different observers consistently identify contamination hazards and consistently classify water source types using standard typologies. This study aimed to quantify inter-observer agreement in hazard identification and classification of rural water sources. Six observers separately visited 146 domestic water sources in Siaya County, Kenya, in wet and dry seasons. Each observer independently classified the source type and conducted a sanitary risk inspection using a standard protocol. Water source types assigned by an experienced observer were cross-tabulated against those of his colleagues, as were contamination hazards identified, and inter-observer agreement measures calculated. Agreement between hazards observed by the most experienced observer versus his colleagues was significant but low (intra-class correlation = 0.49), with inexperienced observers detecting fewer hazards. Inter-observer agreement in classifying water sources was strong (Cohen's kappa = 0.84). However, some source types were frequently misclassified, such as sources adapted to cope with water insecurity (e.g. tanks drawing on both piped and rainwater). Observers with limited training and experience thus struggle to consistently identify hazards using existing protocols, suggesting observation protocols require revision and their implementation should be supported by comprehensive training. Findings also indicate that field survey teams struggle to differentiate some water source types based on a standard water source classification, particularly sources adapted to cope with water insecurity. These findings demonstrate uncertainties underpinning international monitoring and analyses of safe water access via household surveys.

Bridging the knowledge-practice gap in tuberculosis contact management in a high-burden setting: a mixed-methods protocol for a multicenter health system strengthening study

Background

People in close contact with tuberculosis should have screening and appropriate management, as an opportunity for active case detection and prevention. However, implementation of tuberculosis contact screening and management is limited in high-burden settings. Behaviour change is needed across three levels of the healthcare system—policymakers, healthcare providers, and patients. To bridge the wide policy-practice gap, this study draws on the Consolidated Framework for Implementation Research, the Behaviour Change Wheel, and the RE-AIM model (Reach, Effectiveness, Adoption, Implementation, Maintenance) to respectively understand barriers, implement change, and evaluate process and outcome.

Methods

This methods paper describes a mixed-methods intervention study in Eastern Indonesia. Quantitative data will be collected during baseline, intervention, and sustainability periods and analyzed using time series analysis. The primary outcome is the number of individuals completing tuberculosis preventive therapy by the end of the two-year intervention phase. Of an estimated 10,000 contacts during this period, we anticipate that a minimum of 416 will be found to have active TB or will complete preventive therapy. Qualitative data (semi-structured interviews, focus group discussions, and observations) will be collected from consenting healthcare providers, patients, and contacts. Activities to promote policy implementation include healthcare provider training, quarterly continuous quality improvement workshops, a social media discussion forum, and promotional materials. The Consolidated Framework for Implementation Research will be used to identify reasons for limited policy implementation at baseline. The Behaviour Change Wheel will be used to ensure that a suitable range of activities are implemented to facilitate change. The RE-AIM model will be used as the evaluation framework.

Discussion

Use of theoretical frameworks in combination can ensure a comprehensive understanding of, and robust response to, health policy underimplementation. The selected frameworks are highly applicable to this pragmatic intervention study, in a setting where End TB Strategy targets will not be met without substantial behavior change within health systems. Continuous quality improvement cycles will provide a way to engage staff and stakeholders in understanding local data to motivate behavior change. If successful, up to 500 people could be prevented from developing complications of tuberculosis through early case-finding or receiving preventive therapy over a two-year period.

Study registration

Australian New Zealand Clinical Trials Register 375803.

Standardized radiographic interpretation of thoracic tuberculosis in children

There is a lack of standardized approach and terminology to classify the diverse spectrum of manifestations in tuberculosis. It is important to recognize the different clinical and radiographic patterns to guide treatment. As a result of changing epidemiology, there is considerable overlap in the radiologic presentations of primary tuberculosis and post-primary tuberculosis. In this article we promote a standardized approach in clinical and radiographic classification for children suspected of having or diagnosed with childhood tuberculosis. We propose standardized terms to diminish confusion and miscommunication, which can affect management. In addition, we present pitfalls and limitations of imaging.

Improving access to tuberculosis preventive therapy and treatment for children

Children suffer a huge burden of disease in tuberculosis (TB) endemic countries. This disease burden was largely invisible when TB control programmes focused exclusively on adults with sputum smear-positive disease. High-level advocacy and better data have improved visibility, but the establishment of functional paediatric TB programmes remains challenging. The key issues that limit children's access to TB preventive therapy and treatment in endemic areas are briefly discussed. Barriers to preventive therapy include (1) the perceived inability to rule out active disease, (2) fear of creating drug resistance, (3) non-implementation of existing guidelines in the absence of adequate monitoring, and (4) poor adherence with long preventive therapy courses. Barriers to TB treatment include (1) perceived diagnostic difficulties, (2) non-availability of chest radiography, (3) young children presenting to unprepared maternal and child health (MCH) services, and (4) the absence of child-friendly formulations. With drug-resistant disease there is currently no guidance on the use of preventive therapy and treatment is usually restricted to cases with bacteriologically confirmed disease, which excludes most young children from care, even if their likely source case has documented drug-resistant TB.