Socioeconomic factors associated with asthma prevalence and severity among children living in low-income South African communities.

BACKGROUND: Rates of asthma, poverty and social deprivation are high among young people in South Africa (SA), yet asthma interventions largely remain focused on biomedical factors. OBJECTIVE: To investigate associations between socioeconomic factors and childhood asthma. METHODS: We recruited 6 002 children aged 10 - 17 years from six low-income urban and rural sites in three SA provinces. Self-report questionnaires measured health status, sociodemographics and socioeconomic factors. Logistic regression and mediation analyses were used to test models of risk factors for asthma prevalence and severity (frequency of attacks). RESULTS: Child anxiety (odds ratio (OR) 1.08; 95% confidence interval (CI) 1.04 - 1.12) and community violence (OR 1.14; 95% CI 1.00 - 1.30) were associated with increased odds of having asthma. Children doing more outdoor housework (OR 0.83; 95% CI 0.71 - 0.98) and living in greater poverty (OR 0.93; 95% CI 0.88 - 0.99) had lower odds of having asthma. Severe asthma was predicted by child depression (OR 1.14; 95% CI 1.03 - 1.26) and greater household poverty (OR 1.14; 95% CI 1.01 - 1.28). Most socioeconomic factors operated in 'risk pathways', wherein structural factors (e.g. urban living) were associated with individual factors (e.g. fewer outdoor tasks), which predicted greater odds of having asthma or severe exacerbations. CONCLUSIONS: This study suggests the need to consider the context of childhood asthma in SA for improved prevention and treatment. A multidisciplinary approach may be more effective than a biomedical model, given the plausible effects of psychosocial stress and poverty on asthma outcomes.

Bronchoscopic assessment of airway involvement in children presenting with clinically significant airway obstruction due to tuberculosis.

INTRODUCTION: The incidence of complicated lymph node disease in tuberculosis (TB) in children less than 15 years of age varies from 8% to 38%. There are few published studies on the bronchoscopic appearance and severity of airway obstruction caused by lymph node involvement of the airways resulting from Mycobacterium tuberculosis (MTB). The primary aim of the study was to describe the flexible bronchoscopic findings of lymph node involvement of the airways caused by MTB in children with severe airway obstruction. The secondary aim was to compare the degree of airway involvement in HIV negative to HIV positive children as well the airway involvement caused by drug susceptible and drug resistant MTB. PATIENTS AND METHODS: All children between 1 month and 13 years of age presenting with clinical and radiological signs of significant airway obstruction suspected of being the result of MTB infection were studied. In addition to routine examination for MTB disease a flexible bronchoscope and bronchoalveolar lavage (BAL) for MTB culture were performed on all the children. RESULTS: Two hundred fifty children (16% HIV positive) were studied. Median age was 14 months and the median weight 8.5 kg. MTB was cultured from 78% (n = 194) of children with the BAL positive in 44%. The BAL culture yield was significantly higher in children with radiological evidence of pneumonia when compared to children with airway involvement alone (P = 0.004). The bronchial tree was obstructed on the right in 85% (n = 212), the left in 66% (n = 164), and both sides in 53% (n = 132) of cases. The commonest sites of obstruction were bronchus intermedius (72%) and left main bronchus (62%). Drug resistance was present in 16% (n = 28). There was no difference in the site or severity of obstruction when comparing drug susceptible to drug resistant cases or HIV positive to HIV negative children. CONCLUSIONS: Bronchus intermedius and left main bronchus were the commonest sites of airway obstruction. The MTB culture yield from BAL was higher in children with pneumonia when compared to those with airway involvement alone. HIV positive or children with drug resistant TB did not have more severe airway obstruction.

Modelling the cost-effectiveness of strategies to prevent tuberculosis in child contacts in a high-burden setting.

BACKGROUND: WHO recommends isoniazid preventive therapy (IPT) for young children in close contact with an infectious tuberculosis (TB) case. No models have examined the cost effectiveness of this recommendation. METHODS: A decision analysis model was developed to estimate health and economic outcomes of five TB infection screening strategies in young household contacts. In the no-testing strategy, children received IPT based on age and reported exposure. Other strategies included testing for infection with a tuberculin skin test (TST), interferon γ release assay (IGRA) or IGRA after TST. Markov modelling included age-specific disease states and probabilities while considering risk of re-infection in a high-burden country. RESULTS: Among the 0-2-year-old cohort, the no-testing strategy was most cost effective. The discounted societal cost of care per life year saved ranged from US$237 (no-testing) to US$538 (IGRA only testing). Among the 3-5-year-old cohort, strategies employing an IGRA after a negative TST were most effective, but were associated with significant incremental cost (incremental cost-effectiveness ratio >US$233 000), depending on the rate of Mycobacterium tuberculosis infection. CONCLUSION: Screening for M tuberculosis infection and provision of IPT in young children is a highly cost-effective intervention. Screening without testing for M tuberculosis infection is the most cost-effective strategy in 0-2-year-old children and the preferred strategy in 3-5-year-old children. Lack of testing capacity should therefore not be a barrier to IPT delivery. These findings highlight the cost effectiveness of contact tracing and IPT delivery in young children exposed to TB in high-burden countries.

Implementation of an oxygen concentrator system in district hospital paediatric wards throughout Malawi.

PROBLEM: Hypoxaemia in children with severe or very severe pneumonia is a reliable predictor of mortality, yet oxygen was not available in most paediatric wards in Malawi. APPROACH: The Child Lung Health Programme in Malawi made oxygen available by supplying oxygen concentrators and essential supplies to 22 district and 3 regional hospitals' paediatric wards. Five key steps were taken to introduce concentrators: (1) develop a curriculum and training materials; (2) train staff on use and maintenance; (3) retrain electromedical departments on maintenance and repair; (4) conduct training once concentrators arrived in the country; and (5) distribute concentrators once staff had been trained. LOCAL SETTING: The paediatric wards in 3 regional and 22 government district hospitals and 3 regional electromedical engineering departments in Malawi. RELEVANT CHANGES: Main changes were: (1) provision of a source of oxygen in every paediatric ward in all district hospitals; (2) training of electrical engineering and health personnel in the use, maintenance and repair of oxygen concentrators; and (3) setting-up of high-dependency rooms or areas for severely ill children where oxygen is administered. LESSONS LEARNED: It is feasible to implement an oxygen system using concentrators throughout a low-income country. Oxygen delivery requires trained staff with necessary equipment and supplies. Regular maintenance and supervision are essential to ensure optimal utilization.

Radiographic signs and symptoms in children treated for tuberculosis: possible implications for symptom-based screening in resource-limited settings.

BACKGROUND: The World Health Organization advises active tracing of children younger than 5 years old in household contact with a sputum smear-positive tuberculosis index case. This study compared radiographic disease manifestations in 2 groups of children treated for tuberculosis in an endemic setting: those who presented with suspicious symptoms; and those actively traced as household contacts of an adult index case. METHODS: We conducted a prospective descriptive study from February 2003 through October 2004 at 5 primary health care clinics in Cape Town South Africa, including all children (younger than 5 years old) treated for tuberculosis (TB). RESULTS: A total of 326 children (younger than 5 years old) received antituberculosis treatment; 190 (58.3%) presented with suspicious symptoms, and 136 (41.7%) were actively traced contacts. Children were categorized as; "not TB" 71 (22%), intrathoracic tuberculosis 230 (70%) and extrathoracic tuberculosis 25 (8%). Significantly more actively traced contacts were categorized as "not TB" (odds ratio, 7.4; 95% confidence interval, 3.8-14.3), or demonstrated elements of the primary complex only on the chest radiograph (odds ratio, 26.2; 95% confidence interval, 8.6-89.2), compared with children who presented with suspicious symptoms. Of all children diagnosed with intrathoracic tuberculosis, 20 of 230 (9%) reported no symptoms, all of whom demonstrated elements of the primary complex only. CONCLUSIONS: The majority of actively traced contacts had minimal disease. Symptom-based screening would have identified all but 9% of children diagnosed with intrathoracic tuberculosis, all of whom demonstrated elements of the primary complex only. Further investigation is required to establish whether symptom-based screening can be justified to improve access to preventive chemotherapy in resource-limited endemic settings.