Household contact investigation for tuberculosis in Vietnam: study protocol for a cluster randomized controlled trial

Nutritional supplementation to prevent tuberculosis incidence in household contacts of patients with pulmonary tuberculosis in India (RATIONS): a field-based, open-label, cluster-randomised, controlled trial

BACKGROUND

In India, tuberculosis and undernutrition are syndemics with a high burden of tuberculosis coexisting with a high burden of undernutrition in patients and in the population. The aim of this study was to determine the effect of nutritional supplementation on tuberculosis incidence in household contacts of adults with microbiologically confirmed pulmonary tuberculosis.

METHODS

In this field-based, open-label, cluster-randomised controlled trial, we enrolled household contacts of 2800 patients with microbiologically confirmed pulmonary tuberculosis across 28 tuberculosis units of the National Tuberculosis Elimination Programme in four districts of Jharkhand, India. The tuberculosis units were randomly allocated 1:1 by block randomisation to the control group or the intervention group, by a statistician using computer-generated random numbers. Although microbiologically confirmed pulmonary tuberculosis patients in both groups received food rations (1200 kcal, 52 grams of protein per day with micronutrients) for 6 months, only household contacts in the intervention group received monthly food rations and micronutrients (750 kcal, 23 grams of protein per day with micronutrients). After screening all household contacts for co-prevalent tuberculosis at baseline, all participants were followed up actively until July 31, 2022, for the primary outcome of incident tuberculosis (all forms). The ascertainment of the outcome was by independent medical staff in health services. We used Cox proportional hazards model and Poisson regression via the generalised estimating equation approach to estimate unadjusted hazard ratios, adjusted hazard ratios (aHRs), and incidence rate ratios (IRRs). This study is registered with CTRI-India, CTRI/2019/08/020490.

FINDINGS

Between Aug 16, 2019, and Jan 31, 2021, there were 10 345 household contacts, of whom 5328 (94·8%) of 5621 household contacts in the intervention group and 4283 (90·7%) of 4724 household contacts in the control group completed the primary outcome assessment. Almost two-thirds of the population belonged to Indigenous communities (eg, Santhals, Ho, Munda, Oraon, and Bhumij) and 34% (3543 of 10 345) had undernutrition. We detected 31 (0·3%) of 10 345 household contact patients with co-prevalent tuberculosis disease in both groups at baseline and 218 (2·1%) people were diagnosed with incident tuberculosis (all forms) over 21 869 person-years of follow-up, with 122 of 218 incident cases in the control group (2·6% [122 of 4712 contacts at risk], 95% CI 2·2-3·1; incidence rate 1·27 per 100 person-years) and 96 incident cases in the intervention group (1·7% [96 of 5602], 1·4-2·1; 0·78 per 100 person-years), of whom 152 (69·7%) of 218 were patients with microbiologically confirmed pulmonary tuberculosis. Tuberculosis incidence (all forms) in the intervention group had an adjusted IRR of 0·61 (95% CI 0·43-0·85; aHR 0·59 [0·42-0·83]), with an even greater decline in incidence of microbiologically confirmed pulmonary tuberculosis (0·52 [0·35-0·79]; 0·51 [0·34-0·78]). This translates into a relative reduction of tuberculosis incidence of 39% (all forms) to 48% (microbiologically confirmed pulmonary tuberculosis) in the intervention group. An estimated 30 households (111 household contacts) would need to be provided nutritional supplementation to prevent one incident tuberculosis.

INTERPRETATION

To our knowledge, this is the first randomised trial looking at the effect of nutritional support on tuberculosis incidence in household contacts, whereby the nutritional intervention was associated with substantial (39-48%) reduction in tuberculosis incidence in the household during 2 years of follow-up. This biosocial intervention can accelerate reduction in tuberculosis incidence in countries or communities with a tuberculosis and undernutrition syndemic.

FUNDING

Indian Council of Medical Research-India TB Research Consortium.

The second national anti-tuberculosis drug resistance survey in Tanzania, 2017-2018

OBJECTIVE

To determine the levels and patterns of resistance to first- and second-line anti-tuberculosis (TB) drugs among new and previously treated sputum smear positive pulmonary TB (PTB) patients.

METHODS

We conducted a nationally representative cross-sectional facility-based survey in June 2017-July 2018 involving 45 clusters selected based on probability proportional to size. The survey aimed to determine the prevalence of anti-TB drug resistance and associated risk factors among smear positive PTB patients in Tanzania. Sputum samples were examined using smear microscopy, Xpert MTB/RIF, culture and drug susceptibility testing (DST). Logistic regression was used to account for missing data and sampling design effects on the estimates and their standard errors.

RESULTS

We enrolled 1557 TB patients, including 1408 (90.4%) newly diagnosed and 149 (9.6%) previously treated patients. The prevalence of multidrug-resistant TB (MDR-TB) was 0.85% [95% confidence interval (CI): 0.4-1.3] among new cases and 4.6% (95% CI: 1.1-8.2) among previously treated cases. The prevalence of Mycobacterium tuberculosis strains resistant to any of the four first-line anti-TB drugs (isoniazid, rifampicin, streptomycin and ethambutol) was 1.7% among new TB patients and 6.5% among those previously treated. Drug resistance to all first-line drugs was similar (0.1%) in new and previously treated patients. None of the isolates displayed poly-resistance or extensively drug-resistant TB (XDR-TB). The only risk factor for MDR-TB was history of previous TB treatment (odds ratio = 5.7, 95% CI: 1.9-17.2).

CONCLUSION

The burden of MDR-TB in the country was relatively low with no evidence of XDR-TB. Given the overall small number of MDR-TB cases in this survey, it will be beneficial focusing efforts on intensified case detection including universal DST.

Cost-effectiveness of household contact investigation for detection of tuberculosis in Pakistan

OBJECTIVES

Despite WHO guidelines recommending household contact investigation, and studies showing the impact of active screening, most tuberculosis (TB) programmes in resource-limited settings only carry out passive contact investigation. The cost of such strategies is often cited as barriers to their implementation. However, little data are available for the additional costs required to implement this strategy. We aimed to estimate the cost and cost-effectiveness of active contact investigation as compared with passive contact investigation in urban Pakistan.

METHODS

We estimated the cost-effectiveness of 'enhanced' (passive with follow-up) and 'active' (household visit) contact investigations compared with standard 'passive' contact investigation from providers and the programme's perspective using a simple decision tree. Costs were collected in Pakistan from a TB clinic performing passive contact investigation and from studies of active contact tracing interventions conducted. The effectiveness was based on the number of patients with TB identified among household contacts screened.

RESULTS

The addition of enhanced contact investigation to the existing passive mode detected 3.8 times more cases of TB per index patient compared with passive contact investigation alone. The incremental cost was US$30 per index patient, which yielded an incremental cost of US$120 per incremental patient identified with TB. The active contact investigation was 1.5 times more effective than enhanced contact investigation with an incremental cost of US$238 per incremental patient with TB identified.

CONCLUSION

Our results show that enhanced and active approaches to contact investigation effectively identify additional patients with TB among household contacts at a relatively modest cost. These strategies can be added to the passive contact investigation in a high burden setting to find the people with TB who are missed and meet the End TB strategy goals.

Decline of Tuberculosis Burden in Vietnam Measured by Consecutive National Surveys, 2007-2017

Vietnam, a high tuberculosis (TB) burden country, conducted national TB prevalence surveys in 2007 and 2017. In both surveys participants were screened by using a questionnaire and chest radiograph; sputum samples were then collected to test for Mycobacterium tuberculosis by smear microscopy and Löwenstein-Jensen culture. Culture-positive, smear-positive, and smear-negative TB cases were defined by laboratory results, and the prevalence of tuberculosis was compared between the 2 surveys. The results showed prevalence of culture-positive TB decreased by 37% (95% CI 11.5%–55.4%), from 199 (95% CI 160–248) cases/100,000 adults in 2007 to 125 (95% CI 98–159) cases/100,000 adults in 2017. Prevalence of smear-positive TB dropped by 53% (95% CI 27.0%–69.7%), from 99 (95% CI 78–125) cases/100,000 adults to 46 (95% CI 32–68) cases/100,000 adults; smear-negative TB showed no substantial decrease. Replacing microscopy with molecular methods for primary diagnostics might enhance diagnosis of pulmonary TB cases and further lower TB burden.

Risk factors for TB among household contacts of patients with smear-positive TB in eight provinces of Vietnam: a nested case-control study

BACKGROUND

Tuberculosis (TB) continues to account for significant morbidity and mortality annually. Household contacts (HHCs) of persons with TB are a key population for targeting prevention and control interventions. We aimed to identify risk factors associated with developing TB among HHCs.

METHODS

We conducted a nested case-control study among HHCs in eight provinces in Vietnam who were enrolled in a randomized control trial of active case finding for TB. Cases were any HHCs diagnosed and registered with TB within the Vietnam National TB programme during two years of follow-up. Controls were selected by simple random sampling from the remaining HHCs. Risk factor data were collected at enrolment and during follow-up. A logistic regression model was developed to determine predictors of TB among HHCs.

RESULTS

We selected 1,254 HHCs for the analysis; 214 cases and 1,040 controls. Underlying characteristics varied between both groups; cases were older, more likely to be male, higher proportion of reported previous TB and diabetes. Risk factors associated with a TB diagnosis included being male (aOR 1.4; 95% CI: 1.03-2.0), residing in an urban setting (aOR 1.8; 1.3-2.5), prior TB (aOR 4.6; 95% CI: 2.5-8.7), history of diabetes (aOR 3.1; 95% CI: 1.7-5.8), current smoking (aOR 3.1; 95% CI: 2.2-4.4) and prolonged history of coughing in the source case at enrolment (OR 1.6; 95% CI: 1.1-2.3).

CONCLUSIONS

Household contacts remain and important key population for TB prevention and control. TB programmes should ensure effective contact investigations are implemented for household contacts, particularly those with additional risk factors for developing tuberculosis.

Household contact investigation for the detection of tuberculosis in Vietnam: economic evaluation of a cluster-randomised trial

BACKGROUND

Active case finding is recommended as an important strategy to control tuberculosis, particularly in low-income and middle-income countries with a high prevalence of the disease. However, the costs and cost-effectiveness of active case finding are unclear due to the absence of evidence from randomised trials. We assessed the costs and cost-effectiveness of an active case finding strategy in Vietnam, where there is a high prevalence of tuberculosis.

METHODS

We conducted an economic evaluation alongside the Active Case Finding in Tuberculosis (ACT2) trial-a pragmatic cluster-randomised controlled trial in 70 districts across eight provinces of Vietnam. Patients aged 15 years and older with smear-positive pulmonary tuberculosis were recruited to the trial if they lived with one or more other household members. Household contacts were verbally invited to the clinic by the index patient with tuberculosis. ACT2 compared a combination of active and passive case finding with usual care (passive case finding) of household contacts of patients with tuberculosis from a health system perspective. Clustering occurred at the district and household level. Districts were the unit of randomisation, and we used minimisation to ensure balance of intervention and control districts within each province. In the intervention group, participants were invited to attend screening at baseline, 6 months, 12 months, and 24 months. We determined health-care costs with a standardised national costing survey and reported results in 2017 $US. The primary outcome of our study was disability-adjusted life years (DALYs) averted over a 24-month period. ACT2 was registered prospectively with the Australian and New Zealand Clinical Trials Registry, number ACTRN126.100.00600044.

FINDINGS

Between Aug 11, 2010, and Aug 11, 2015, 10 964 index patients and 25 707 household contacts completed the ACT2 study. There were 10 069 household contacts in the intervention group and 15 638 household contacts in the control group. The incremental cost-effectiveness ratio per DALY averted was $544 (330-1375).

INTERPRETATION

Active case finding was shown to be highly cost-effective in a setting with a high prevalence of tuberculosis. Investment in the wide-scale implementation of this programme in Vietnam should be strongly supported.

FUNDING

Australian National Health and Medical Research Council.

The second national tuberculosis prevalence survey in Vietnam

Introduction

Tuberculosis (TB) remains a significant cause of morbidity and mortality in Vietnam. The current TB burden is unknown as not all individuals with TB are diagnosed, recorded and notified. The second national TB prevalence survey was conducted in 2017–2018 to assess the current burden of TB disease in the country.

Method

Eighty-two clusters were selected using a multistage cluster sampling design. Adult (≥15 years of age) residents having lived for 2 weeks or more in the households of the selected clusters were invited to participate in the survey. The survey participants were screened for TB by a questionnaire and digital chest X-ray after providing written informed consent. Individuals with a positive symptom screen and/or chest X-ray suggestive of TB were asked to provide sputum samples to test for Mycobacterium tuberculosis by Ziehl-Neelsen direct light microscopy, Xpert MTB/RIF G4, BACTEC MGIT960 liquid culture and Löwenstein-Jensen solid culture. Bacteriologically confirmed TB cases were defined by an expert panel following a standard decision tree.

Result

Of 87,207 eligible residents, 61,763 (70.8%) participated, and 4,738 (7.7%) screened positive for TB. Among these, 221 participants were defined as bacteriologically confirmed TB cases. The estimated prevalence of bacteriologically confirmed adult pulmonary TB was 322 (95% CI: 260–399) per 100,000, and the male-to-female ratio was 4.0 (2.8–5.8, p<0.001). In-depth interviews with the participants with TB disease showed that only 57.9% (95% CI: 51.3–64.3%) reported cough for 2 weeks or more and 32.1% (26.3–38.6%) did not report any symptom consistent with TB, while their chest X-ray results showed that 97.7% (95% CI: 94.6–99.1) had abnormal chest X-ray images suggesting TB.

Conclusion

With highly sensitive diagnostics applied, this survey showed that the TB burden in Vietnam remains high. Half of the TB cases were not picked up by general symptom-based screening and were identified by chest X-ray only. Our results indicate that improving TB diagnostic capacity and access to care, along with reducing TB stigma, need to be top priorities for TB control and elimination in Vietnam.

Recurrence of tuberculosis among patients following treatment completion in eight provinces of Vietnam: A nested case-control study

BACKGROUND

Patients completing treatment for tuberculosis (TB) in high-prevalence settings face a risk of developing recurrent disease. This has important consequences for public health, given its association with drug resistance and a poor prognosis. Previous research has implicated individual factors such as smoking, alcohol use, HIV, poor treatment adherence, and drug resistant disease as risk factors for recurrence. However, little is known about how these factors co-act to produce recurrent disease. Furthermore, perhaps factors related to the index disease means higher burden/low resource settings may be more prone to recurrent disease that could be preventable.

METHODS

We conducted a case-control study nested within a cohort of consecutively enrolled adults who were being treated for smear positive pulmonary TB in 70 randomly selected district clinics in Vietnam. Cases were patients with recurrent TB, identified by follow-up from the parent cohort study. Controls were selected from the cohort by random sampling. Information on demographic, clinical and disease-related characteristics was obtained by interview. Treatment information was extracted from clinic registries. Logistic regression, with stepwise selection, was used to develop a fully adjusted model for the odds of recurrence of TB.

RESULTS

We recruited 10,964 patients between October 2010 and July 2013. Median follow-up was 988 days. At the end of follow-up, 505 patients (4.7%) with recurrence were identified as cases and 630 other patients were randomly selected as controls. Predictors of recurrence included multidrug-resistant (MDR)-TB (adjusted odds ratio 79.6; 95% CI: 25.1-252.0), self-reported prior TB therapy (aOR=2.5; 95% CI: 1.7-3.5), and incomplete adherence (aOR=1.9; 95% CI 1.1-3.1).

CONCLUSIONS

Index disease treatment history is a leading determinant of relapse among patients with TB in Vietnam. Further research is required to identify interventions that will reduce the risk of recurrent disease and enhance its early detection within high-risk populations.

Household-Contact Investigation for Detection of Tuberculosis in Vietnam

BACKGROUND

Active case finding is a top priority for the global control of tuberculosis, but robust evidence for its effectiveness in high-prevalence settings is lacking. We sought to evaluate the effectiveness of household-contact investigation, as compared with standard, passive measures alone, in Vietnam.

METHODS

We performed a cluster-randomized, controlled trial at clinics in 70 districts (local government areas with an average population of approximately 500,000 in urban areas and 100,000 in rural areas) in eight provinces of Vietnam. Health workers at each district clinic or hospital were assigned to perform either household-contact intervention plus standard passive case finding (intervention group) or passive case finding alone (control group). In the intervention districts, household contacts of patients with positive results for tuberculosis on sputum smear microscopy (smear-positive tuberculosis) were invited for clinical assessment and chest radiography at baseline and at 6, 12, and 24 months. The primary outcome was the cumulative incidence of registered cases of tuberculosis among household contacts of patients with tuberculosis during a 2-year period.

RESULTS

In 70 selected districts, we enrolled 25,707 household contacts of 10,964 patients who had smear-positive pulmonary tuberculosis. In the 36 districts that were included in the intervention group, 180 of 10,069 contacts were registered as having tuberculosis (1788 cases per 100,000 population), as compared with 110 of 15,638 contacts (703 per 100,000) in the control group (relative risk of the primary outcome in the intervention group, 2.5; 95% confidence interval [CI], 2.0 to 3.2; P<0.001); the relative risk of smear-positive disease among household contacts in the intervention group was 6.4 (95% CI, 4.5 to 9.0; P<0.001).

CONCLUSIONS

Household-contact investigation plus standard passive case finding was more effective than standard passive case finding alone for the detection of tuberculosis in a high-prevalence setting at 2 years. (Funded by the Australian National Health and Medical Research Council; ACT2 Australian New Zealand Clinical Trials Registry number, ACTRN12610000600044 .).

The effect of delay on contact tracing

We consider a model for an infectious disease in the onset of an outbreak. We introduce contact tracing incorporating a tracing delay. The effect of randomness in the delay and the effect of the length of this delay in comparison to the infectious period of the disease respectively to a latency period on the effect of tracing, given e.g. by the change of the reproduction number, is analyzed. We focus particularly on the effect of randomness in the tracing delay.

Screening strategies for active tuberculosis: focus on cost-effectiveness

In recent years, there has been renewed interest in screening for active tuberculosis (TB), also called active case-finding (ACF), as a possible means to achieve control of the global TB epidemic. ACF aims to increase the detection of TB, in order to diagnose and treat patients with TB earlier than if they had been diagnosed and treated only at the time when they sought health care because of symptoms. This will reduce or avoid secondary transmission of TB to other people, with the long-term goal of reducing the incidence of TB. Here, the history of screening for active TB, current screening practices, and the role of TB-diagnostic tools are summarized and the literature on cost-effectiveness of screening for active TB reviewed. Cost-effectiveness analyses indicate that community-wide ACF can be cost-effective in settings with a high incidence of TB. ACF among close TB contacts is cost-effective in settings with a low as well as a high incidence of TB. The evidence for cost-effectiveness of screening among HIV-infected persons is not as strong as for TB contacts, but the reviewed studies suggest that the intervention can be cost-effective depending on the background prevalence of TB and test volume. None of the cost-effectiveness analyses were informed by data from randomized controlled trials. As the results of randomized controlled trials evaluating different ACF strategies will become available in future, we will hopefully gain a better understanding of the role that ACF can play in achieving global TB control.

Barriers to adherence with tuberculosis contact investigation in six provinces of Vietnam: a nested case-control study

Background

Close contacts of patients with tuberculosis (TB) have a substantial risk of developing the disease, particularly during the first year after exposure. Household contact investigation has recently been recommended as a strategy to enhance case detection in high-burden countries. However the barriers to its implementation in these settings remain poorly understood.

Methods

A nested case–control study was conducted in Vietnam within the context of a large cluster randomised controlled trial of active screening for TB in household contacts of patients with pulmonary TB. The study population comprised contacts (and their index patients) from 12 Districts in six provinces throughout the country. Cases were contacts (and their index patients) that did not attend the scheduled screening appointment. Controls were those who did attend. We assessed relevant knowledge, attitudes and practices in cases and controls.

Results

The acceptability of contact investigation was high among both cases (n = 109) and controls (n = 194). Both cases (47%) and controls (36%) commonly reported discrimination against people with TB. Cases were less likely than controls to understand that sharing sleeping quarters with a TB patient increased their risk of disease (OR 0.46, 0.27 – 0.78) or recognise TB as an infectious disease (OR 0.65, 0.39 – 1.08). A higher proportion of cases than controls held the mistaken traditional belief that a non-infectious form of TB caused the disease (OR 1.69, 1.02 – 2.78).

Conclusions

The knowledge, attitudes and practices of contacts and TB patients influence their ongoing participation in contact investigation. TB case detection policies in high-prevalence settings can be strengthened by systematically evaluating and addressing locally important barriers to attendance.

Trial registration

Australian New Zealand Clinical Trials Registry, ACTRN12610000600044.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-0816-0) contains supplementary material, which is available to authorized users.