Exposure to combustion of solid fuel and tuberculosis: a matched case-control study

The present study was conducted in Benin to ascertain the association between exposure to combustion of solid fuel (coal and biomass) and tuberculosis. Cases were consecutive, sputum smear-positive tuberculosis patients never previously treated for tuberculosis for as long as 1 month. Two controls were selected from the neighbourhood of each case, matched by age and sex by a predefined procedure. A total of 200 new smear-positive cases and 400 neighbourhood controls were enrolled. In univariate analysis, using solid fuel for cooking (OR 1.7, 95% CI 1.1-2.8), ever smoking (OR 5.5, 95% CI 3.1-9.8), male sex (OR 10.5, 95% CI 1.6-71.1), daily use of alcoholic beverages (OR 2.3, 95% CI 1.2-4.2) and having a family member with tuberculosis in the previous 5 yrs (OR 30.5, 95% CI 10.8-85.8) were all significantly associated with tuberculosis cases. When all significant variables were entered into a multivariate conditional logistic regression model, the association between using solid fuel for cooking and tuberculosis cases was no longer statistically significant (adjusted OR 1.4, 95% CI 0.7-2.7). In conclusion, the association between exposure to combustion of solid fuel and tuberculosis was relatively weak and not statistically significant.

Tuberculosis in humans and its epidemiology, diagnosis and treatment in the United States

Tuberculosis (TB) is a pulmonary and systemic disease caused by Mycobacterium tuberculosis complex species. TB is spread from person to person by airborne transmission. Several factors determine the probability of transmission, including the infectiousness of the source patient and the nature of the environment where exposure occurs. This initial infection (primary TB) rapidly progresses to disease in some persons (especially children and immunocompromised persons), but resolves spontaneously in most individuals. This condition in which the organism lies dormant is known as latent TB infection (LTBI). In the United States, the diagnosis of LTBI is made with either the tuberculin skin test or an interferon-gamma release assay. LTBI is treated with isoniazid (INH; usually for 9 months) to prevent progression to TB disease. Up to 5% of immunocompetent persons will progress to TB disease at some time in the future, even decades after infection, if they are not treated for LTBI. Pulmonary TB disease is diagnosed using a combination of chest radiography and microscopic examination, culture and nucleic acid amplification testing of sputum. Treatment of drug-susceptible TB consists of at least 6 months of an INH and rifampin-containing regimen (with ethambutol and pyrazinamide for the first 2 months). In the United States, drug-resistant TB is relatively rare (approximately 1% of all patients), and is treated with an 18-24 month individualized regimen based on drug susceptibility test results.

Tuberculosis in humans and animals: an overview

Tuberculosis (TB) is a significant disease for both humans and animals. Susceptibility to Mycobacterium tuberculosis is relatively high in humans, other primates and guinea pigs. Cattle, rabbits and cats are susceptible to M. bovis and are quite resistant to M. tuberculosis. Wild hoofed stock is generally susceptible to M. bovis, but few reports are available on the isolation of M. tuberculosis. Swine and dogs are susceptible to both M. bovis and M. tuberculosis. M. bovis accounts for only a small percentage of the reported cases of TB in humans; however, it is a pathogen of significant economic importance in wild and domestic animals around the globe, especially in countries where little information is available on the incidence of M. bovis infection in humans. Unlike transmission of M. bovis from cattle to humans, the role of human-to-human airborne transmission in the spread of M. bovis has been somewhat controversial. Investigations are needed to elucidate the relative importance of M. bovis on TB incidence in humans, especially in developing countries. Efforts should be concentrated in countries where human immunodeficiency virus (HIV) infection is widespread, as HIV-infected individuals are more susceptible to mycobacterial disease. Eradication of M. bovis in cattle and pasteurisation of dairy products are the cornerstones of the prevention of human disease.

Inconsistent dosing of anti-tuberculosis drugs in Taipei, Taiwan

SETTING

Taipei City, Taiwan.

OBJECTIVES

To evaluate prescribing practices for anti-tuberculosis drugs in the treatment of tuberculosis (TB).

METHOD

Medical audit of the medical charts of all patients notified and treated for TB in Taiwan in 2003 to determine the treatment regimens prescribed and to compare these with recommended dosages.

RESULTS

A total of 24 different anti-tuberculosis regimens were prescribed. Of 1700 patients notified, 1096 (64.5%) had their body weight recorded. Of 506 patients prescribed a three-drug fixed-dose combination (FDC), the dosage was adequate in 374 (73.9%), too low in 100 (19.8%) and too high in 32 (6.3%). Of 75 patients prescribed a two-drug FDC, the dosage was adequate in 57 (76.0%), too low in 15 (20.0%) and too high in 3 (4.0%). Of 481 patients prescribed rifampicin, the dosage was adequate in 302 (62.8%), too low in 152 (31.6%) and too high in 27 (5.6%). Of 451 patients prescribed isoniazid, the dosage was adequate in 396 (87.8%), too low in 29 (6.4%) and too high in 26 (5.8%).

CONCLUSION

The prescribing practices for anti-tuberculosis drugs were substandard and need improvement. These findings imply that the National TB Programme needs strengthening.

Baseline sputum time to detection predicts month two culture conversion and relapse in non-HIV-infected patients

BACKGROUND

Few biomarkers are available to identify tuberculosis (TB) patients at risk of delayed sputum conversion and relapse.

OBJECTIVES

To investigate whether baseline pre-treatment time to detection (TTD) of culture predicted 2-month bacteriological conversion and TB relapse.

METHODS

A total of 263 non-HIV-infected smear-positive previously untreated pulmonary TB patients were prospectively followed from diagnosis until treatment outcome after 6 months' treatment and TB recurrence within 24 months.

RESULTS

The median TTD was 3 days (range 1-17). Of 211 (80.2%) patients with favourable treatment outcome, 22 (10.4%) had recurrence, while 12 (5.7%) had confirmed relapse. Culture conversion at 2 months was associated in univariate analysis with the presence and number of cavities, extensive parenchymal involvement, male sex, sputum smear grading and TTD. In multiple logistic regression, TTD or smear grading and extensive parenchymal involvement both predicted month 2 conversion. Relapse was predicted by TTD, sex, body mass index, smear grading and number of cavities in univariate analysis, and in multivariate regression by TTD and sputum smear grading.

CONCLUSIONS

Baseline TTD and smear grading predicted month 2 culture conversion, relapse and also recurrence. These markers may be useful to identify non-HIV-infected patients at risk of recurrence, and may be relevant in clinical trials.

Recording isoniazid preventive therapy delivery to children: operational challenges

Despite recommendations to provide isoniazid preventive therapy (IPT) to eligible children aged <5 years who are in close contact with an infectious tuberculosis (TB) case, IPT delivery in high-burden settings remains poor. To evaluate the current system supporting IPT delivery to children in an urban community, South Africa, we reviewed the recording practices of a local clinic regarding management of children exposed to a current adult TB case. No standardised IPT management tools existed. Only 21% of children eligible for IPT had documentation of IPT delivery. There is a need to implement systems that support IPT recommendations in high-burden settings.

Indoor solid fuel combustion and tuberculosis: is there an association?

OBJECTIVES

To assess the strength of evidence in published articles for an association between indoor solid fuel combustion and tuberculosis.

METHODS

PubMed, a private database and Google Scholar were searched up to May 2008, as was the Cochrane Library (2008, issue 4), to identify articles on the association between indoor air pollution and tuberculous infection, tuberculosis disease and tuberculosis mortality. Each article initially chosen as acceptable for inclusion was reviewed for data extraction by three different reviewers using a standard format. Strength of evidence was determined by pre-determined criteria.

RESULTS

The full texts of 994 articles were examined for a final selection of 10 possible articles, of which six met the inclusion criteria. All articles investigated the association between exposure to solid fuel (coal and biomass) smoke and tuberculosis disease. Three (50%) of the six studies included in the systematic review showed a significant effect of exposure to solid fuel combustion and tuberculosis disease-one high-quality case-control study and two cross-sectional studies.

CONCLUSION

Despite the plausibility of an association, available original studies looking at this issue do not provide sufficient evidence of an excess risk of tuberculosis due to exposure to indoor coal or biomass combustion. Because the number of studies identified was small, new studies are needed before more definitive conclusions can be reached.

Serious adverse reactions in a tuberculosis programme setting in Kyrgyzstan

Serious adverse reactions among new smear-positive patients were studied in a programme setting in Kyrgyzstan. Two per cent of patients on tuberculosis (TB) treatment had to interrupt treatment for > or =1 week, and more than 80% of the reactions occurred during the first month of treatment. Pyrazinamide was the most common causative agent, followed by rifampicin.

How health systems in sub-Saharan Africa can benefit from tuberculosis and other infectious disease programmes

Weak and dysfunctional health systems in low-income countries, particularly in sub-Saharan Africa, are recognised as major obstacles to attaining the health-related Millennium Development Goals by 2015. Some progress is being made towards achieving the targets of Millennium Development Goal 6 for tuberculosis (TB), HIV/AIDS and malaria, with the achievements largely resulting from clearly defined strategies and intervention delivery systems combined with large amounts of external funding. This article is divided into four main sections. The first highlights the crucial elements that are needed in low-income countries in sub-Saharan Africa to deliver good quality health care through general health systems. The second discusses the main characteristics of infectious disease and TB control programmes. The third illustrates how TB control and other infectious disease programmes can help to strengthen these components, particularly in human resources; infrastructure; procurement and distribution; monitoring, evaluation and supervision; leadership and stewardship. The fourth and final section looks at progress made to date at the international level in terms of policy and guidelines, with some specific suggestions about this might be moved forward at the national level. For TB and other infectious disease programmes to drive broad improvements in health care systems and patient care, the lessons that have been learnt must be consciously applied to the broader health system, and sufficient financial input and the engagement of all players are essential.

Isoniazid preventive therapy for people living with HIV: public health challenges and implementation issues

Isoniazid preventive therapy (IPT) is recognised as an important component of collaborative tuberculosis (TB) and human immunodeficiency virus (HIV) activities to reduce the burden of TB in people living with HIV (PLHIV). However, there has been little in the way of IPT implementation at country level. This failure has resulted in a recent call to arms under the banner title of the 'Three I's' (infection control to prevent nosocomial transmission of TB in health care settings, intensified TB case finding and IPT). In this paper, we review the background of IPT. We then discuss the important challenges of IPT in PLHIV, namely responsibility and accountability for the implementation, identification of latent TB infection, exclusion of active TB and prevention of isoniazid resistance, length of treatment and duration of protective efficacy. We also highlight several research questions that currently remain unanswered. We finally offer practical suggestions about how to scale up IPT in the field, including the need to integrate IPT into a package of care for PLHIV, the setting up of operational projects with the philosophy of 'learning while doing', the development of flow charts for eligibility for IPT, the development and implementation of care prior to antiretroviral treatment, and finally issues around procurement, distribution, monitoring and evaluation. We support the implementation of IPT, but only if it is done in a safe and structured way. There is a definite risk that 'sloppy' IPT will be inefficient and, worse, could lead to the development of multidrug-resistant TB, and this must be avoided at all costs.

Registering initial defaulters and reporting on their treatment outcomes

This Unresolved Issues article highlights three original articles that appeared last year in the Journal discussing the phenomenon of initial defaulters. There are three important challenges with patients that appear in the laboratory sputum register but are not recorded in the tuberculosis (TB) patient register: the first is how to identify these patients, trace them and get them on to treatment as soon as possible; the second is how to register and report on these cases as part of the case-finding component of TB control; and the third is whether to include these initial default patients in the cohort analysis of treatment outcomes. We recommend a step-wise approach to these challenges and advocate that these patients be included, wherever possible, in the TB patient register and in the cohort analysis of treatment outcomes.

Informed patient consent for defaulter tracing: should we obtain it?

Active default tracing is an integral part of tuberculosis (TB) programmatic control. It can be differentiated into the tracing of defaulters (patients not seen at the clinic for > or =2 months) and 'late patients' (late for their scheduled appointments). Tracing is carried out to obtain reliable information about who has truly died, transferred out or stopped treatment, and, if possible, to persuade those who have stopped treatment to resume. This is important because, unlike routine care for non-communicable diseases, TB has the potential for transmission to other members of the community, and therefore presents the issue of the rights of the individual over the rights of the community. For this reason, default or 'late patient' tracing (defined together as default tracing in this article) has been incorporated into standard practice in most TB programmes and, in many industrialised countries, it is also a part of public health legislation. In resource-poor countries with limited access to phones or e-mails, default tracing involves active home visits. In this Unresolved Issues article, we discuss the need for patient consent within both the programmatic and the research context; we describe how this subject arose during operational research training at the Research Institute of Tuberculosis in Japan; we provide comments from individuals who are experienced and skilled at international and national TB control; and finally we offer some conclusions about the way forward. This is not an easy subject, and we welcome open debate on the issue.

Protecting patients' rights, ensuring safety and quality assurance in tuberculosis prevalence surveys

The conduct of biomedical studies is guided by statements of internationally recognised principles of human rights. The first principle of the Nuremberg Code was the centrality of voluntary participation of subjects with informed consent. All prevalence surveys should be reviewed by the appropriate ethics review committees. Each potential survey participant should be adequately informed of the aims, methods and sources of funding of the survey, any possible conflicts of interest, the institutional affiliations of the researchers, the anticipated benefits and potential risks of the study, and any discomfort it may entail. Attention should be paid to safety in each component of the survey. Test procedures that require particular attention are chest radiography (CXR) and bacteriological examination. Quality assurance should be applied to all aspects of research and, in particular, to any measurements undertaken, including CXR assessments, laboratory examinations and questionnaire and data management. Furthermore, to ensure comparability of data from different surveys, it is important to apply the same survey design and methodology and to use the same reporting format.

Tuberculosis outcomes in Taipei: factors associated with treatment interruption for 2 months and death

SETTING

All individuals reported as being treated for pulmonary tuberculosis (PTB) among citizens of Taipei City, Taiwan, in 2003.

OBJECTIVES

To investigate risk factors associated with treatment interruption for at least 2 consecutive months and death.

DESIGN

The outcome of PTB cases was determined by consulting medical charts.

RESULTS

Of 1127 PTB patients registered, 824 (73.1%) were successfully treated, 189 (16.8%) died, 65 (5.8%) interrupted treatment, 17 (1.5%) were still on treatment 15 months after commencing treatment and 32 (2.8%) failed. The only significant factor associated with treatment interruption was visits to other health facilities after commencing tuberculosis (TB) treatment. TB patients had a standardised mortality ratio of 8.7 (95%CI 7.5-10.0). Factors significantly associated with death were age (adjusted hazard ratio [adjHR] 1.06. 95%CI 1.05-1.08), sputum culture not performed/unknown (adjHR 2.07, 95%CI 1.47-2.92), and comorbidity with respiratory disease (adjHR 1.68, 95%CI 1.24-2.27), infectious disease (adjHR 2.80, 95%CI 2.07-3.78), renal disease (adjHR 2.58, 95%CI 1.82-3.66) or cancer (adjHR 3.31, 95%CI 2.35-4.65), compared with other patients.

CONCLUSION

Visits to other health facilities were associated with interruption of treatment for at least 2 months. A high proportion of deaths was due to old age and comorbidity.

How to identify tuberculosis cases in a prevalence survey

The identification of pulmonary tuberculosis (TB) cases in a prevalence survey is a challenge, as diagnostic methods are labour-intensive and large numbers of individuals need to be screened because the prevalence rate is low (almost never greater than 1,200 per 100,000 population). Three testing methods are used: questionnaires, chest radiography (CXR) and bacteriological tests, including sputum smear microscopy and culture. These methods can be applied in four strategies to identify cases. The most sensitive strategy is to apply all methods to each eligible individual. The next most sensitive option is to apply the questionnaire, CXR and sputum smear microscopy to each eligible individual and obtain sputum for culture from those individuals with symptoms, abnormalities on the CXR or a positive smear. If laboratory capacity is limited, screening using symptom enquiry and CXR can be used to select those individuals at highest risk of TB. These individuals are then requested to submit sputum for smear microscopy and culture. If neither CXR nor culture is available, sputum samples may be collected from all eligible individuals and examined by an enhanced microscopy method such as fluorescence microscopy. Case definitions are ideally based on the combined results of symptom enquiry, CXR and bacteriology.

Tuberculosis prevalence surveys: rationale and cost

This article is the first of the educational series 'Assessing tuberculosis (TB) prevalence through population-based surveys'. The series will give overall guidance in conducting cross-sectional surveys of pulmonary TB (PTB) disease. TB prevalence surveys are most valuable in areas where notification data obtained through routine surveillance are of unproven accuracy or incomplete, and in areas with an estimated prevalence of bacteriologically confirmed TB of more than 100 per 100,000 population. To embark on a TB prevalence survey requires commitment from the national TB programme, compliance in the study population, plus availability of trained staff and financial resources. The primary objective of TB prevalence surveys is to determine the prevalence of PTB in the general population aged >or=15 years. Limitations of TB prevalence surveys are their inability to assess regional or geographic differences in prevalence of TB, estimate the burden of childhood TB or estimate the prevalence of extra-pulmonary TB. The cost of a prevalence survey is typically US$ 4-15 per person surveyed, and up to US$ 25 per person with radiographic screening. A survey of 50,000 people, of limited precision, would typically cost US$ 200,000-1,250,000.

From suspect to patient: tuberculosis diagnosis and treatment initiation in health facilities in South Africa

SETTING

Thirteen primary health care (PHC) facilities in the Stellenbosch District, South Africa.

OBJECTIVE

To assess the use of a sputum register to evaluate the tuberculosis (TB) diagnostic process and the initiation of TB treatment in selected PHC facilities in a country with a centralised laboratory system.

DESIGN

This prospective study was conducted between April 2004 and March 2005. The names of all individuals submitting sputum samples for TB testing were noted in a newly introduced sputum register. We classified all TB suspects with two positive smears as TB cases and consulted TB treatment registers until 3 months after sputum submission to determine how many had started treatment.

RESULTS

A total of 4062 persons aged > or =15 years submitted sputum samples, of whom 2484 were TB suspects. There were 2037 suspects with at least two results, 367 (18%) had at least two positive smears and 64 (17%) of these did not start treatment (initial defaulters). Over the entire diagnostic process, up to 5% of TB cases were missed, and up to 26% did not start treatment and were not reported.

CONCLUSION

By correcting diagnostic weaknesses identified in the sputum register, PHC facilities will be able to detect, treat and cure a higher percentage of TB patients.

Initial default from tuberculosis treatment: how often does it happen and what are the reasons?

A study in 11 primary health care facilities in and around Cape Town determined the proportion of bacteriologically confirmed tuberculosis (TB) cases who did not start treatment (initial default) and identified reasons for it. Databases from centralised laboratories were compared with electronic TB treatment registers. Fourteen per cent (373/2758) of TB suspects were TB cases. Of the 58 (16%) initial defaulters, 14 (24%) died, while 26 (45%) could not be interviewed for address-related reasons. The 18 subjects who were interviewed indicated reasons for initial default that were (56%) or were not (44%) directly linked to services. High initial default rates require improvement in the quality of health services.

COPD management. Part II. Relevance for resource-poor settings

Chronic obstructive pulmonary disease (COPD) is a preventable disease and its prevalence, already high in middle- and low-income countries, is expected to increase in the next decade. Global initiatives, including those against the tobacco industry to stop the tobacco epidemic, are fundamental to reduce the expected morbidity and mortality due to COPD. National health expenditure is generally low in the majority of developing countries, where financial and human resources are lacking and are primarily devoted to infectious diseases. To face these challenges, it is essential to strengthen political commitment to prioritising resource allocation to discourage tobacco use and to implement cost-effective standardised case management. The management of COPD could be more affordable in resource-poor countries if the cheaper spirometers currently on the market were made available and by the use of generic essential drugs. The organisation within clinical services of integrated management of respiratory diseases, including tuberculosis, as recommended by the World Health Organization in its Practical Approach to Lung Health, and by the International Union Against Tuberculosis and Lung Disease in its Comprehensive Approach to Lung Health, would help to improve health systems and skills of health personnel, reduce health costs and improve the quality of care of patients with chronic respiratory diseases.

Factors associated with a clinician's decision to stop anti-tuberculosis treatment before completion

OBJECTIVES

To investigate the diagnosis of pulmonary tuberculosis (PTB) and factors associated with a clinician's decision to stop anti-tuberculosis treatment before completion.

DESIGN

The medical charts of all citizens of Taipei City, Taiwan, reported to have received treatment for PTB in 2003 were investigated.

RESULTS

Of 1126 PTB patients, 512 (45.5%) started treatment immediately based solely on chest X-ray (CXR) findings; treatment for 214 (19.0%) was based on a positive sputum smear for acid-fast bacilli, for 261 (23.2%) it was based on other findings and for 139 (12.3%) it was based on a positive mycobacterial culture. Of the 1126 PTB patients, 156 (13.9%) had their diagnosis of TB changed by a clinician. Multivariate analysis shows that patients whose diagnosis was based on CXR or other findings, female patients, patients who interrupted treatment for 2 months, patients who continued care at other health facilities (transfer) and patients with lung cancer were significantly more likely to have their diagnosis changed than other groups.

CONCLUSION

A substantial proportion of patients were prescribed anti-tuberculosis treatment based on CXR findings alone, and a considerable proportion were advised to stop treatment before completing a full course, findings that require the immediate attention of Taiwan's National Tuberculosis Programme.

Tobacco and tuberculosis: a qualitative systematic review and meta-analysis

OBJECTIVES

To assess the strength of evidence in published articles for an association between smoking and passive exposure to tobacco smoke and various manifestations and outcomes of tuberculosis (TB). Clinicians and public health workers working to fight TB may not see a role for themselves in tobacco control because the association between tobacco and TB has not been widely accepted. A qualitative review and meta-analysis was therefore undertaken.

METHODS

Reference lists, PubMed, the database of the International Union Against Tuberculosis and Lung Disease and Google Scholar were searched for a final inclusion of 42 articles in English containing 53 outcomes for data extraction. A quality score was attributed to each study to classify the strength of evidence according to each TB outcome. A meta-analysis was then performed on results from included studies.

RESULTS

Despite the limitations in the data available, the evidence was rated as strong for an association between smoking and TB disease, moderate for the association between second-hand smoke exposure and TB disease and between smoking and retreatment TB disease, and limited for the association between smoking and tuberculous infection and between smoking and TB mortality. There was insufficient evidence to support an association of smoking and delay, default, slower smear conversion, greater severity of disease or drug-resistant TB or of second-hand tobacco smoke exposure and infection.

CONCLUSIONS

The association between smoking and TB disease appears to be causal. Smoking can have an important impact on many aspects of TB. Clinicians can confidently advise patients that quitting smoking and avoiding exposure to others' tobacco smoke are important measures in TB control.

Providing and monitoring quality service for smoking cessation in tuberculosis care

All tobacco smokers should be identified and provided with a smoking cessation intervention (SCI) during tuberculosis (TB) treatment. To ensure that this occurs, the intervention process should be recorded and monitored. Monitoring is the best guarantee that care is standardised and offered equitably to all patients. It allows for evaluation of processes and outcomes so that population needs can be identified and appropriate techniques added or updated. In this article we propose steps for brief intervention as a part of the monitoring process, using model forms and suggested procedures for filling them in. The suggested forms are a modified TB treatment card that includes information about tobacco use, an SCI patient card to be added to the patient's TB treatment folder, SCI registers and SCI quarterly report forms and a tobacco use questionnaire for evaluation of services.

Accuracy of classification of notified tuberculosis cases in Taiwan

SETTING

Tuberculosis (TB) suspects and cases reported in 2003 in Taiwan.

OBJECTIVES

To evaluate the accuracy of the classification of notified TB cases in Taiwan.

DESIGN

A list of all TB cases reported in 2003 in Taiwan was obtained from the Taiwan Center for Disease Control, along with their classification. TB cases residing in Taipei City were investigated by consulting their medical charts.

RESULTS

Of 1,973 patients, 782 (39.6%) were bacteriologically confirmed, 1,024 (52%) were not bacteriologically confirmed (indeterminate) and 167 (9%) were not TB cases (in whom non-tuberculosis mycobacteria [NTM] was isolated). Of the 1,973 cases, 1,716 (87%) had been treated with anti-tuberculosis drugs, while 257 (13%) had not been treated. Of the 782 bacteriologically confirmed cases, 68 (8.7%) were misclassified as non-notifiable (32 [4.1%] had their diagnosis changed by a clinician and 36 [4.6%] by administrative coding). Of the 167 cases in whom NTM were isolated, 72 (43.1%) were misclassified as TB cases. Of the 257 untreated suspects, 31 (12.1%) did not have any evidence of TB (20 indeterminate and 11 NTM cases) and were questionably classified as newly diagnosed cases.

CONCLUSION

There was substantial misclassification of notified TB cases in Taiwan.