The epidemiology of tuberculosis by ethnic group in Birmingham and its implications for future trends in tuberculosis in the UK

Accurate diagnosis of latent tuberculosis in children, people who are immunocompromised or at risk from immunosuppression and recent arrivals from countries with a high incidence of tuberculosis: systematic review and economic evaluation

BACKGROUND

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB) [(Zopf 1883) Lehmann and Neumann 1896], is a major cause of morbidity and mortality. Nearly one-third of the world's population is infected with MTB; TB has an annual incidence of 9 million new cases and each year causes 2 million deaths worldwide.

OBJECTIVES

To investigate the clinical effectiveness and cost-effectiveness of screening tests [interferon-gamma release assays (IGRAs) and tuberculin skin tests (TSTs)] in latent tuberculosis infection (LTBI) diagnosis to support National Institute for Health and Care Excellence (NICE) guideline development for three population groups: children, immunocompromised people and those who have recently arrived in the UK from high-incidence countries. All of these groups are at higher risk of progression from LTBI to active TB.

DATA SOURCES

Electronic databases including MEDLINE, EMBASE, The Cochrane Library and Current Controlled Trials were searched from December 2009 up to December 2014.

REVIEW METHODS

English-language studies evaluating the comparative effectiveness of commercially available tests used for identifying LTBI in children, immunocompromised people and recent arrivals to the UK were eligible. Interventions were IGRAs [QuantiFERON(®)-TB Gold (QFT-G), QuantiFERON(®)-TB Gold-In-Tube (QFT-GIT) (Cellestis/Qiagen, Carnegie, VA, Australia) and T-SPOT.TB (Oxford Immunotec, Abingdon, UK)]. The comparator was TST 5 mm or 10 mm alone or with an IGRA. Two independent reviewers screened all identified records and undertook a quality assessment and data synthesis. A de novo model, structured in two stages, was developed to compare the cost-effectiveness of diagnostic strategies.

RESULTS

In total, 6687 records were screened, of which 53 unique studies were included (a further 37 studies were identified from a previous NICE guideline). The majority of the included studies compared the strength of association for the QFT-GIT/G IGRA with the TST (5 mm or 10 mm) in relation to the incidence of active TB or previous TB exposure. Ten studies reported evidence on decision-analytic models to determine the cost-effectiveness of IGRAs compared with the TST for LTBI diagnosis. In children, TST (≥ 5 mm) negative followed by QFT-GIT was the most cost-effective strategy, with an incremental cost-effectiveness ratio (ICER) of £18,900 per quality-adjusted life-year (QALY) gained. In immunocompromised people, QFT-GIT negative followed by the TST (≥ 5 mm) was the most cost-effective strategy, with an ICER of approximately £18,700 per QALY gained. In those recently arrived from high TB incidence countries, the TST (≥ 5 mm) alone was less costly and more effective than TST (≥ 5 mm) positive followed by QFT-GIT or T-SPOT.TB or QFT-GIT alone.

LIMITATIONS

The limitations and scarcity of the evidence, variation in the exposure-based definitions of LTBI and heterogeneity in IGRA performance relative to TST limit the applicability of the review findings.

CONCLUSIONS

Given the current evidence, TST (≥ 5 mm) negative followed by QFT-GIT for children, QFT-GIT negative followed by TST (≥ 5 mm) for the immunocompromised population and TST (≥ 5 mm) for recent arrivals were the most cost-effective strategies for diagnosing LTBI that progresses to active TB. These results should be interpreted with caution given the limitations identified. The evidence available is limited and more high-quality research in this area is needed including studies on the inconsistent performance of tests in high-compared with low-incidence TB settings; the prospective assessment of progression to active TB for those at high risk; the relative benefits of two-compared with one-step testing with different tests; and improved classification of people at high and low risk for LTBI.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014009033.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Epidemiology and disease burden of tuberculosis in children: a global perspective

Our understanding of the tuberculosis (TB) epidemic in children is incomplete due to challenges in diagnosis and reporting. Children have also been largely excluded from research and advocacy. However, the tide appears to be turning and interest in pediatric TB is increasing. In this article, we explore the epidemiology of childhood TB by first reviewing the natural history of TB in children and the factors that impact on each of the stages from exposure to disease. We then discuss how these factors affect what we see at a country and regional level. Finally, we assess the burden of childhood TB globally.

Investigating tuberculosis trends in England

OBJECTIVE

To investigate the factors associated with the increasing incidence of tuberculosis in England.

DESIGN

Prospective national surveillance study.

METHODS

Measurement of relative trends in demographic, clinical and microbiological characteristics of tuberculosis cases reported in England between 1999 and 2003.

RESULTS

Between 1999 and 2003, the number of tuberculosis cases reported in England increased by 19% from 5539 to 6608. Significant increases in tuberculosis cases were seen in the non-UK-born population who were recent entrants to the UK (arrival less than 5 years prior to diagnosis) relative to cases in the UK-born population, both in London [1.08; 95% confidence interval (CI) 1.02-1.14] and outside London (1.22; 95% CI 1.16-1.28). Cases of tuberculosis co-infected with human immunodeficiency virus (HIV) increased significantly both in London (1.19; 95% CI 1.12-1.27) and outside London (1.22; 95% CI 1.12-1.33) relative to cases not known to be co-infected with HIV. Small increases in the number of cases living in less-deprived areas were observed relative to those in the most-deprived areas (1.11; 95% CI 1.02-1.21) in London. The number of cases of isoniazid-resistant (1.09; 95% CI 1.02-1.16) and multi-drug-resistant tuberculosis (1.22; 95% CI 1.02-1.45) increased relative to drug-susceptible cases in London.

CONCLUSIONS

Tuberculosis remains strongly associated with deprivation, but no real change in the distribution of tuberculosis cases by deprivation was observed over the study period. The proportion of tuberculosis cases co-infected with HIV has increased, but migration explains most of the recent trends in tuberculosis in England. Measures that target latent tuberculosis infection could have an increased role to play alongside measures against active disease in reducing the incidence of tuberculosis in the UK.

Global epidemiology of paediatric tuberculosis

Tuberculosis is one of the major infections affecting children worldwide. It causes significant morbidity and mortality, especially in infants and young children. Factors such as overcrowding, poverty and the HIV epidemic have all contributed to the resurgence of tuberculosis globally. The highest rates of tuberculosis occur in resource-poor countries and over the last decade case notifications in children have been increasing steadily, particularly in Sub-Saharan Africa. Mycobacterium tuberculosis infects millions of children worldwide every year, yet accurate information on the extent and distribution of disease in children is not available for most of the world. We describe some of the unique aspects of tuberculosis infection in children and review the epidemiology of disease in children worldwide.

Assessing the burden of respiratory disease in the UK

This review explores the health and social burden of some of the main respiratory diseases (asthma, chronic obstructive pulmonary disease, cryptogenic fibrosing alveolitis, cystic fibrosis, lung cancer, mesothelioma, obstructive sleep apnoea and tuberculosis) in order to increase awareness of these diseases and highlight areas where improvements in care are required. The overall impact of respiratory diseases in the U.K. in terms of prevalence, mortality, morbidity and economic costs, with particular reference to secondary care has been considered and comparisons made with the rest of Europe where data are available. Respiratory diseases are responsible for a significant proportion of serious morbidity and premature death among the population of the U.K. and they will continue to present a growing challenge; special support is needed to tackle this burden.

Socioeconomic and ethnic group differences in self reported health status and use of health services by children and young people in England: cross sectional study

OBJECTIVES

To examine whether self reported health status and use of health services varies in children of different social class and ethnic group.

DESIGN

Cross sectional study from the 1999 health survey for England.

SUBJECTS

6648 children and young adults aged 2-20 years.

SETTING

Private households in England.

MAIN OUTCOME MEASURES

Proportion of children (or their parents) reporting episodes of acute illness in the preceding fortnight and prevalence of self reported longstanding illness. Proportion reporting specific illnesses. Proportion reporting that they had consulted a general practitioner in the preceding fortnight, attended hospital outpatient departments in the three preceding months, or been admitted to hospital in the preceding year.

RESULTS

Large socioeconomic differences were observed between ethnic subgroups; a higher proportion of Afro-Caribbean, Indian, Pakistani, and Bangladeshi children belonged to lower social classes than the general population. The proportion of children and young adults reporting acute illnesses in the preceding two weeks was lower in Bangladeshi and Chinese subgroups (odds ratio 0.41, 95% confidence interval 0.27 to 0.61 and 0.46, 0.28 to 0.77, respectively) than in the general population. Longstanding illnesses was less common in Bangladeshi and Pakistani children (0.52, 0.40 to 0.67 and 0.57, 0.46 to 0.70) than in the general population. Irish and Afro-Caribbean children reported the highest prevalence of asthma (19.5% and 17.7%) and Bangladeshi children the lowest (8.2%). A higher proportion of Afro-Caribbean children reported major injuries than the general population (11.0% v 10.0%), and children from all Asian subgroups reported fewer major and minor injuries than the general population. Indian and Pakistani children were more likely to have consulted their general practitioner in the preceding fortnight than the general population (1.86, 1.35 to 2.57 and 1.51, 1.13 to 2.01, respectively). Indian, Pakistani, Bangladeshi, and Chinese children were less likely to have attended outpatient departments in the preceding three months. No significant differences were found between ethnic groups in the admission of inpatients to hospitals. Acute and chronic illness were the best predictors of children's use of health services. Social classes did not differ in self reported prevalence of treated infections, major injuries, or minor injuries, and no socioeconomic differences were seen in the use of primary and secondary healthcare services.

CONCLUSIONS

Children's use of health services reflected health status rather than ethnic group or socioeconomic status, implying that equity of access has been partly achieved, although reasons why children from ethnic minority groups are able to access primary care but receive less secondary care need to be investigated.

Ecological analysis of ethnic differences in relation between tuberculosis and poverty

OBJECTIVE

To examine the effect of ethnicity on the relation between tuberculosis and deprivation.

DESIGN

Retrospective ecological study comparing incidence of tuberculosis in white and south Asian residents of the 39 electoral wards in Birmingham with ethnic specific indices of deprivation.

SETTING

Birmingham, 1989-93.

SUBJECTS

1516 notified cases of tuberculosis.

MAIN OUTCOME MEASURES

Rates of tuberculosis and measures of deprivation.

RESULTS

Univariate analysis showed significant associations of tuberculosis rates for the whole population with several indices of deprivation (P<0.01) and with the proportion of the population of south Asian origin (P<0.01). All deprivation covariates were positively associated with each other but on multiple regression, higher level of overcrowding was independently associated with tuberculosis rates. For the white population, overcrowding was associated with tuberculosis rates independently of other variables (P=0.0036). No relation with deprivation was found for the south Asian population in either single or multivariable analyses.

CONCLUSIONS

Poverty is significantly associated with tuberculosis in the white population, but no such relation exists for those of Asian ethnicity. These findings suggest that causal factors, and therefore potential interventions, will also differ by ethnic group.