Household contact investigation to improve tuberculosis control

Impact and cost-effectiveness of short-course tuberculosis preventive treatment for household contacts and people with HIV in 29 high-incidence countries: a modelling analysis

BACKGROUND

Guidelines and implementation of tuberculosis preventive treatment (TPT) vary by age and HIV status. Specifically, TPT is strongly recommended for people living with HIV/AIDS (PLWHA) and household contacts younger than 5 years but only conditionally recommended for older contacts. Cost remains a major barrier to implementation. The aim of this study was to evaluate the cost-effectiveness of TPT for household contacts and PLWHA.

METHODS

We developed a state-transition model to simulate short-course TPT for household contacts and PLWHA in 29 high-incidence countries based on data from previous studies and public databases. Our primary outcome was the incremental cost-effectiveness ratio, expressed as incremental discounted costs (2020 US$, including contact investigation costs) per incremental discounted disability-adjusted life year (DALY) averted, compared with a scenario without any TPT or contact investigation. We propagated uncertainty in all model parameters using probabilistic sensitivity analysis and also evaluated the sensitivity of results to the screening algorithm used to rule out active disease, the choice of TPT regimen, the modelling time horizon, assumptions about TPT coverage, antiretroviral therapy discontinuation, and secondary transmission.

FINDINGS

Between 2023 and 2035, scaling up TPT prevented 0·9 (95% uncertainty interval 0·4-1·6) people from developing tuberculosis and 0·13 (0·05-0·27) tuberculosis deaths per 100 PLWHA, at an incremental cost of $15 (9-21) per PLWHA. For household contacts, TPT (with contact investigation) averted 1·1 (0·5-2·0) cases and 0·7 (0·4-1·0) deaths per 100 contacts, at a cost of $21 (17-25) per contact. Cost-effectiveness was most favourable for household contacts younger than 5 years ($22 per DALY averted) and contacts aged 5-14 years ($104 per DALY averted) but also fell within conservative cost-effectiveness thresholds in many countries for PLWHA ($722 per DALY averted) and adult contacts ($309 per DALY averted). Costs per DALY averted tended to be lower when compared with a scenario with contact investigation but no TPT. The cost-effectiveness of TPT was not substantially altered in sensitivity analyses, except that TPT was more favourable in analysis that considered a longer time horizon or included secondary transmission benefits.

INTERPRETATION

In many high-incidence countries, short-course TPT is likely to be cost-effective for PLWHA and household contacts of all ages, regardless of whether contact investigation is already in place. Failing to implement tuberculosis contact investigation and TPT will incur a large burden of avertable illness and mortality in the next decade.

FUNDING

Unitaid.

Household Contact Tuberculosis Screening Adherence and Associated Factors Among Pulmonary Tuberculosis Patients on Follow-Up at Health Facilities in Shashamane Town, Southeast Ethiopia

Background

The greatest risk of getting tuberculosis (TB) infection is contact with patients who have pulmonary tuberculosis (PTB). The World Health Organization (WHO) strongly recommends tuberculosis screening for all household contacts of PTB patients. However, there is no information on household contact screening adherence among PTB patients in Shashamane town.

Methods

A facility-based mixed-method cross-sectional study was conducted from July 1 to November 30, 2021 among consecutively selected 392 PTB patients and 23 purposely selected key informants. Data were collected using a pre-tested interviewer administered questionnaire and leading questions. Data analysis was made using SPSS version 25 and in-depth interview information was analyzed based on thematic areas. Bivariable followed by multivariable logistic regression with 95% CI were conducted. P-value<0.05 was considered to identify statistically significant factors.

Results

The overall adherence to household contact screening (HHCS) was 44.4% (95% CI: 39.3, 49.1). Having under fifteen years of contact (AOR=2.386, 95% CI: 1.44, 3.96), diploma and above education status (AOR=3.43, 95% CI: 1.286, 9.15), good knowledge (AOR=2.999, 95% CI: 1.79, 5.03), favorable attitude (AOR=2.409, 95% CI: 1.45, 4.02), getting health education (AOR=3.287, 95% CI: 1.92, 5.63) and smear positive type of PTB (AOR=2.156, 95% CI: 1.28, 3.62) were factors significantly associated with HHCS adherence. Workload, facility readiness and care provide commitments were also identified from qualitative data.

Conclusion and Recommendation

HHCS adherence in our study was sub-optimal referenced to WHO and national recommendations that all household contact should be screened. Having age less than fifteen years contact, education status, knowledge, attitude, receiving health education and type of pulmonary tuberculosis were factors associated with adherence. We recommend increasing community awareness of TB, providing health education TB patients and their families, strengthening positive attitudes toward HHC screening and strengthening the commitment of health professionals to screen for HHCs.

The Global Expansion of LTBI Screening and Treatment Programs: Exploring Gaps in the Supporting Economic Evidence

The global burden of latent TB infection (LTBI) and the progression of LTBI to active TB disease are important drivers of ongoing TB incidence. Addressing LTBI through screening and TB preventive treatment (TPT) is critical in order to end the TB epidemic by 2035. Given the limited resources available to health ministries around the world in the fight against TB, we must consider economic evidence for LTBI screening and treatment strategies to ensure that limited resources are used to achieve the biggest health impact. In this narrative review, we explore key economic evidence around LTBI screening and TPT strategies in different populations to summarize our current understanding and highlight gaps in existing knowledge. When considering economic evidence supporting LTBI screening or evaluating different testing approaches, a disproportionate number of economic studies have been conducted in high-income countries (HICs), despite the vast majority of TB burden being borne in low- and middle-income countries (LMICs). Recent years have seen a temporal shift, with increasing data from low- and middle-income countries (LMICs), particularly with regard to targeting high-risk groups for TB prevention. While LTBI screening and prevention programs can come with extensive costs, targeting LTBI screening among high-risk populations, such as people living with HIV (PLHIV), children, household contacts (HHC) and immigrants from high-TB-burden countries, has been shown to consistently improve the cost effectiveness of screening programs. Further, the cost effectiveness of different LTBI screening algorithms and diagnostic approaches varies widely across settings, leading to different national TB screening policies. Novel shortened regimens for TPT have also consistently been shown to be cost effective across a range of settings. These economic evaluations highlight key implementation considerations such as the critical nature of ensuring high rates of adherence and completion, despite the costs associated with adherence programs not being routinely assessed and included. Digital and other adherence support approaches are now being assessed for their utility and cost effectiveness in conjunction with novel shortened TPT regimens, but more economic evidence is needed to understand the potential cost savings, particularly in settings where directly observed preventive therapy (DOPT) is routinely conducted. Despite the growth of the economic evidence base for LTBI screening and TPT recently, there are still significant gaps in the economic evidence around the scale-up and implementation of expanded LTBI screening and treatment programs, particularly among traditionally hard-to-reach populations.

Perceptions, preferences, and experiences of tuberculosis education and counselling among patients and providers in Kampala, Uganda: A qualitative study

Tuberculosis (TB) education seeks to increase patient knowledge about TB, while TB counselling seeks to offer tailored advice and support for medication adherence. While universally recommended, little is known about how to provide effective, efficient, patient-centred TB education and counselling (TEC) in low-income, high HIV-TB burden settings. We sought to characterise stakeholder perceptions of TEC in a public, primary care facility in Kampala, Uganda, by conducting focus group discussions with health workers and TB patients in the TB and HIV clinics. Participants valued TEC but reported that high-quality TEC is rarely provided, because of a lack of time, space, staff, planning, and prioritisation given to TEC. To improve TEC, they recommended adopting practices that have proven effective in the HIV clinic, including better specifying educational content, and employing peer educators focused on TEC. Patients and health workers suggested that TEC should not only improve TB patient knowledge and adherence, but should also empower and assist all those undergoing evaluation for TB, whether confirmed or not, to educate their households and communities about TB. Community-engaged research with patients and front-line providers identified opportunities to streamline and standardise the delivery of TEC using a patient-centred, peer-educator model.

Alert sign and symptoms for the early diagnosis of pulmonary tuberculosis: analysis of patients followed by a tertiary pediatric hospital

Background

Intercepting earlier suspected TB (Tuberculosis) cases clinically is necessary to reduce TB incidence, so we described signs and symptoms of retrospective cases of pulmonary TB and tried to evaluate which could be early warning signs.

Methods

We conducted a retrospective descriptive study of pulmonary TB cases in children in years 2005–2017; in years 2018–2020 we conducted a cohort prospective study enrolling patients < 18 years accessed to Emergency Department (ED) with signs/symptoms suggestive of pulmonary TB.

Results

In the retrospective analysis, 226 patients with pulmonary TB were studied. The most frequently described items were contact history (53.5%) and having parents from countries at risk (60.2%). Cough was referred in 49.5% of patients at onset, fever in 46%; these symptoms were persistent (lasting ≥ 10 days) in about 20%. Lymphadenopathy is described in 15.9%. The prospective study enrolled 85 patients of whom 14 (16.5%) were confirmed to be TB patients and 71 (83.5%) were non-TB cases. Lymphadenopathy and contact history were the most correlated variables. Fever and cough lasting ≥ 10 days were less frequently described in TB cases compared to non-TB patients (p < 0.05).

Conclusions

In low TB endemic countries, pulmonary TB at onset is characterized by different symptoms, i.e. persistent fever and cough are less described, while more relevant are contact history and lymphadenopathy. It was not possible to create a score because signs/symptoms usually suggestive of pulmonary TB (considered in the questionnaire) were not significant risk factors in our reality, a low TB country.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13052-022-01288-5.

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.

Evaluating the Quality of Tuberculosis Contact Investigation in Cali, Colombia: A Retrospective Cohort Study

Tuberculosis (TB) contact investigation facilitates earlier TB diagnosis and initiation of preventive therapy, but little data exist about the quality of its implementation. We conducted a retrospective cohort study to evaluate processes of TB contact investigation for index TB patients diagnosed in Cali, Colombia, in 2017, including dropout at each stage and overall yield. We constructed multivariable models to identify predictors of completing 1) the baseline household visit and 2) a follow-up clinic visit for TB evaluation among referred contacts. Sixty-eight percent (759/1,120) of registered TB patients were eligible for contact investigation; 77% (582/759) received a household visit. Odds of completing a household visit were significantly lower among men (adjusted odds ratio [aOR]: 0.6; 95% CI: 0.4-0.9; P = 0.009) and patients living in Cali's western zone (aOR: 0.5; 95% CI: 0.3-0.8; P = 0.008). Among 1880 screened contacts, 31% (n = 582) met the criteria for clinic referral, 47% (n = 271) completed a clinic visit, and 85% (231/271) completed testing. After adjusting for clustering by index patient, odds of completing referral were higher among contacts with cough (aOR: 22; 95% CI: 7.1-66; P < 0.001) and contacts living in the western zone (aOR: 4.1; 95% CI: 1.2-15; P = 0.03). The cumulative probability of a symptomatic contact from an eligible household completing TB evaluation was only 28%. The yield of active TB patients among contacts was only 0.3% (5/1880). Only 16% (17/103) of children aged < 5 years were included, and none of the eight persons were living with HIV-initiated preventive therapy. Routine monitoring of process indicators may facilitate quality improvement to close gaps in contact tracing and increase yield.

Historical review of studies on the effect of treating latent tuberculosis

Tuberculosis Preventive Therapy (TPT) is widely used in particular among high-risk populations such as close contacts and immunosuppressed people mostly in high-income settings. TPT is widely recommended for high-risk populations including HIV-infected and household contacts globally, but is not widely used. Historical trials on risk groups as well as the general population have documented a marked effect on reductions in incidence of active disease among those treated, as well as on prevalence of latent TB infection (LTBI) in populations where massive roll-out of TPT has previously taken place. This review summarizes the results of large historical trials conducted more than 50 years ago among Inuit and African populations as well as risk groups in the USA and Europe exhibiting similarities with current high-burden populations with current limited use of TPT. The trials demonstrated a 27-95% reduction in incidence of active TB among those receiving preventive treatment compared with placebo, with efficacy depending somewhat on length of treatment but mostly on adherence rates. It was possible to achieve satisfactory adherence rates in most of the trial populations and liver toxicity rates were generally low. The historical trials on preventive treatment for LTBI have documented that large-scale TPT is possible and effective even in high-burden populations in high-incidence areas and is therefore a relevant tool to consider in striving to eliminate the TB epidemic.