Tuberculosis screening costs and cost-effectiveness in high-risk groups: a systematic review

Rethinking Tuberculosis Morbidity Quantification: A Systematic Review and Critical Appraisal of TB Disability Weights in Cost-Effectiveness Analyses

BACKGROUND

The disability-adjusted life year (DALY), a key metric for health resource allocation, encompasses morbidity through disability weights. Widely used in tuberculosis cost-effectiveness analysis (CEAs), DALYs play a significant role in informing intervention adopt/reject decisions. This study reviews the values and consistency of disability weights applied in tuberculosis-related CEAs.

METHODS

We conducted a systematic review using the Tufts CEA database, updated to July 2023 with searches in Embase, Scopus and PubMed. Eligible studies needed to have included a cost-per-DALY ratio, and additionally either evaluated a tuberculosis (TB) intervention or included tuberculosis-related weights. We considered all tuberculosis health states: with/without human immunodeficiency virus (HIV) coinfection, TB treatments and treatment side effects. Data were screened and extracted independently by combinations of two authors.

FINDINGS

A total of 105 studies spanning 2002-2023 across 50 countries (mainly low- and middle-income countries) were extracted. Disability weights were sourced primarily from the Global Burden of Disease (GBD; 100/165; 61%), with 17 non-GBD studies additionally referenced, along with primary derivation. Inconsistencies in the utilisation of weights were evident: of the 100 usages of GBD-sourced weights, only in 47 instances (47%) had the weight value been explicitly specified with an appropriate up-to-date reference cited (constituting 28% of all weight usages, 47/165). Sensitivity analyses on weight values had been conducted in 30% of studies (31/105). Twelve studies did not clearly specify weights or their sources; nine further calculated DALYs without morbidity. The review suggests methodological gaps in current approaches for representing important aspects of TB, including TB-HIV coinfection, treatment, drug-resistance, extrapulmonary TB and psychological impacts. We propose a set of best practice recommendations.

INTERPRETATION

There is a need for increased rigour in the application, sensitivity testing and reporting of TB disability weights. Furthermore, there appears a desire among researchers to reflect elements of the tuberculosis experience beyond those allowed for by GBD disability weights.

Systematic review of the economic impact of novel Mycobacterium tuberculosis specific antigen-based skin tests for detection of TB infection compared with tuberculin skin test and interferon-gamma release assays

The Purified Protein Derivative tuberculin skin tests (TST) and blood-based Mycobacterium tuberculosis (M.tb) specific interferon-gamma release assays (IGRA) are the currently used tests for identifying individuals with TB infection for preventive treatment. However, challenges around access and implementation have limited their use. Novel M.tb specific skin tests (TBST) such as Diaskintest, ESAT6-CFP10 (C-TST), C-Tb (also known as Cy-Tb), and DPPD may provide accurate and scalable options but evidence synthesis on their economic impact is lacking. We conducted two separate systematic reviews to compare the costs and cost-effectiveness of (1) the novel skin tests TBST (primary), and (2) TST and IGRA tests (secondary), to support WHO guideline development. We searched for articles presenting economic evaluations of the diagnostic tests using a health provider perspective and related to TB infection in humans. We considered papers written in English, Chinese or Russian. In the primary review, eight studies for novel TBST were found. One study in Brazil assessed cost-effectiveness of C-TST and Diaskintest and seven in Russia assessed the Diaskintest, while none evaluated C-Tb or DPPD. The review showed on average, Diaskintest kit costs (in 2021 USD) $1.60 (1.50 - 1.70), while full unit costs were estimated at $5.07. C-TST unit cost was $9.96. The second review found 32 articles on IGRA and/or the TST. These presented an average TST full unit cost of $37.88, and $87.81 for IGRA. Studies' quality for TBST was limited while high-quality studies were found for TST and IGRA tests. In conclusion, there is limited evidence regarding the costs and cost-effectiveness of novel TBST. Conversely, there is substantial evidence for TST and IGRA tests, but most studies were performed in high-income and low-TB burden settings and their cost-effectiveness varied between and within risk groups without clear economic consensus.

Is it worth screening quarry workers for TB infection in high-incidence areas? A cost-benefit analysis

BACKGROUND

Tuberculosis (TB) infection screening of high-risk groups is an important strategy for achieving End TB targets. A TB infection screening program was implemented for quarry workers from a Portuguese high-incidence area in 2018-2022. We aimed to calculate the cost-benefit of the screening program from the societal perspective.

METHODS

We calculated medical and non-medical direct and indirect screening costs and compared them with the cost savings from averted cases of TB disease. We estimated the number of potentially averted TB disease cases based on the risk of progression of TB infection to TB disease found in the literature.

RESULTS

During the screening program, 997 workers were screened. TB infection was diagnosed in 215 workers, 150 of those initiated preventive treatment. Screening program total costs were €136,295. Twenty-nine TB cases were potentially prevented, what would have costed €152,386. Savings of €16,091 were obtained (€4516, €40898, and -€29322 from the workers, employers, and NHS, respectively).

CONCLUSIONS

The monetary benefit of a TB infection screening program directed to quarry workers in a high-incidence area was greater than its cost. Companies and workers saved substantially more money. TB infection tests that are better predictors of progression to TB disease could reduce NHS costs.

Abbott realtime MTB assay for detecting Mycobacterium tuberculosis complex in respiratory specimens: a cost-benefit analysis

PURPOSE

Molecular screening for Mycobacterium tuberculosis (MTB) can lead to rapid empirical treatment inception and reduce hospitalization time and complementary diagnostic tests. However, in low-prevalence settings, the cost-benefit balance remains controversial due to the high cost.

METHODS

We used a Markov model to perform an economic analysis to evaluate the profit after implementing molecular MTB screening (Period B) compared with conventional culture testing (Period A) in respiratory samples from 7,452 consecutive subjects with presumed tuberculosis (TB).

RESULTS

The proportion of positivity was comparable between both periods (P > 0.05), with a total of 2.16 and 1.78 samples/patient requested in periods A and B, respectively (P < 0.001). The mean length of hospital stay was 8.66 days (95%CI: 7.63-9.70) in Period B and 11.51 days (95%CI: 10.15-12.87) in Period A (P = 0.001). The healthcare costs associated with diagnosing patients with presumed TB were reduced by €717.95 per patient with PCR screening. The probability of remaining hospitalized and the need for a greater number of outpatient specialty care visits were the variables with the most weight in the model.

CONCLUSION

Employing PCR as an MTB screening method in a low-prevalence setting may increase the profits to the system.

HIV-associated tuberculosis in infants, children, and adolescents younger than 15 years: an update on the epidemiology, diagnosis, prevention, and treatment

PURPOSE OF REVIEW

HIV-associated tuberculosis (TB) remains a major driver of morbidity and mortality in children and adolescents younger than 15 years (CLWH). The purpose of this review is to highlight recent findings in the areas of prevention, diagnosis, and treatment of HIV-associated TB in CLWH and to highlight knowledge and implementation gaps.

RECENT FINDINGS

We found that despite access to antiretroviral therapy (ART), high rates of HIV-associated TB are still reported, and with an unacceptably high mortality. There are no advances in screening for TB, but shorter courses of rifapentine-based TB preventive therapy are becoming available. The use of algorithms in TB diagnosis can potentially simplify the therapeutic decision making. There are more data supporting the use of dolutegravir (DTG) with rifampicin and a need to study unadjusted DTG especially in the youngest children. Short course therapy for nonsevere pulmonary TB is currently implemented and programmatic outcome should be studied in CLWH. Low uptake of ART and poor suppression remains an important driver of HIV-associated TB.

SUMMARY

Although screening and diagnosis remains challenging, there are several advances in the prevention and treatment of HIV-associated TB. Effective implementation of these strategies is needed to advance the outcomes of CLWH.

Cost-effectiveness and budget impact of decentralising childhood tuberculosis diagnosis in six high tuberculosis incidence countries: a mathematical modelling study

Background

The burden of childhood tuberculosis remains high globally, largely due to under-diagnosis. Decentralising childhood tuberculosis diagnosis services to lower health system levels could improve case detection, but there is little empirically based evidence on cost-effectiveness or budget impact.

Methods

In this mathematical modelling study, we assessed the cost-effectiveness and budget impact of decentralising a comprehensive diagnosis package for childhood tuberculosis to district hospitals (DH-focused) or primary health centres (PHC-focused) compared to standard of care (SOC). The project was conducted in Cambodia, Cameroon, Côte d'Ivoire, Mozambique, Sierra Leone, and Uganda between August 1st, 2018 and September 30th, 2021. A mathematical model was developed to assess the health and economic outcomes of the intervention from a health system perspective. Estimated outcomes were tuberculosis cases, deaths, disability-adjusted life years (DALYs) and incremental cost-effectiveness ratios (ICERs). We also calculated the budget impact of nationwide implementation. The TB-Speed Decentralization study is registered with ClinicalTrials.gov, NCT04038632.

Findings

For the DH-focused strategy versus SOC, ICERs ranged between $263 (Cambodia) and $342 (Côte d'Ivoire) per DALY averted. For the PHC-focused strategy versus SOC, ICERs ranged between $477 (Cambodia) and $599 (Côte d'Ivoire) per DALY averted. Results were sensitive to TB prevalence and the discount rate used. The additional costs of implementing the DH-focused strategy ranged between $12.8 M (range 10.8-16.4) (Cambodia) and $50.4 M (36.5-74.4) (Mozambique), and between $13.9 M (12.6-15.6) (Sierra Leone) and $134.6 M (127.1-143.0) (Uganda) for the PHC-focused strategy.

Interpretation

The DH-focused strategy may be cost-effective in some countries, depending on the cost-effectiveness threshold used for policy making. Either intervention would require substantial early investment.

Funding

Unitaid.

Cost-effectiveness of active tuberculosis screening among high-risk populations in low tuberculosis incidence countries: a systematic review, 2008 to 2023

BackgroundIn countries with a low TB incidence (≤ 10 cases/100,000 population), active pulmonary tuberculosis (PTB) mostly affects vulnerable populations with limited access to healthcare. Thus, passive case-finding systems may not be successful in detecting and treating cases and preventing further transmission. Active and cost-effective search strategies can overcome this problem.AimWe aimed to review the evidence on the cost-effectiveness (C-E) of active PTB screening programmes among high-risk populations in low TB incidence countries.MethodsWe performed a systematic literature search covering 2008-2023 on PubMed, Embase, Center for Reviews and Dissemination, including Database of Abstracts of Reviews of Effects (DARE), National Health Services Economic Evaluation Database (NHS EED), Global Index Medicus and Cochrane Central Register of Controlled Trials (CENTRAL).ResultsWe retrieved 6,318 articles and included nine in this review. All included studies had an active case-finding approach and used chest X-ray, tuberculin skin test, interferon-gamma release assay and a symptoms questionnaire for screening. The results indicate that screening immigrants from countries with a TB incidence > 40 cases per 100,000 population and other vulnerable populations as individuals from isolated communities, people experiencing homelessness, those accessing drug treatment services and contacts, is cost-effective in low-incidence countries.ConclusionIn low-incidence countries, targeting high-risk groups is C-E. However, due to the data heterogenicity, we were unable to compare C-E. Harmonisation of the methods for C-E analysis is needed and would facilitate comparisons. To outline comprehensive screening and its subsequent C-E analysis, researchers should consider multiple factors influencing screening methods and outcomes.

Economic evaluation of novel Mycobacterium tuberculosis specific antigen-based skin tests for detection of TB infection: A modelling study

Evidence on the economic impact of novel skin tests for tuberculosis infection (TBST) is scarce and limited by study quality. We used estimates on the cost-effectiveness of the use of TBST compared to current tuberculosis infection (TBI) tests to assess whether TBST are affordable and feasible to implement under different country contexts. A Markov model parametrised to Brazil, South Africa and the UK was developed to compare the cost-effectiveness of three TBI testing strategies: (1) Diaskintest (DST), (2) TST test, and (3) IGRA QFT test. Univariate and probabilistic sensitivity analyses over unit costs and main parameters were performed. Our modelling results show that Diaskintest saves $5.60 and gains 0.024 QALYs per patient and $8.40, and 0.01 QALYs per patient in Brazil, compared to TST and IGRA respectively. In South Africa, Diaskintest is also cost-saving at $4.39, with 0.015 QALYs per patient gained, compared to TST, and $64.41, and 0.007 QALYs per patient, compared to IGRA. In the UK, Diaskintest saves $73.33, and gaines 0.0351 QALYs per patient, compared to TST. However, Diaskintest, compared to IGRA, showed an incremental cost of $521.45 (95% CI (500.94-545.07)) per QALY, below the willingness-to-pay threshold of $20.223 per QALY. Diaskintest potentially saves costs and results in greater health gains than the TST and IGRA tests in Brazil and South Africa. In the UK Diaskintest would gain health but also be more costly. Our results have potential external validity because TBST remained cost-effective despite extensive sensitivity analyses.

Tuberculosis screening characteristics amongst freshmen in Changping District, Beijing, China

BACKGROUND

Screening for Tuberculosis (TB) is a critical tactic for minimizing the prevalence of illness within schools. Tuberculosis Preventive Therapy (TPT), in turn, effectively staves off the development of TB from latent tuberculosis infection (LTBI). Unfortunately, there is limited research on LTBI and TPT among students. This study aimed to assess LTBI among freshmen in Changping District and advocate for the implementation of TPT.

METHODS

The prospective study collected data from 12 educational institutions within the Changping District of Beijing. The Kolmogorov - Smirnov test and other statistical methods were used for statistical analysis, [Formula: see text] was obtained using the formula [Formula: see text] nΣA2/nRnC-1, df = (C-1) (R-1). We analyzed potential factors impacting the LTBI rate, and scrutinized the possible causes behind the low application of TPT and its efficacy for LTBI treatment, China.

RESULTS

Among 19,872 freshmen included in this study, 18 active TB cases (91 per 10,0000) and 2236 LTBI cases (11.6% of 19,223) were identified, respectively. Furthermore, of those with LTBI, 1045 (5.4% of 19,223) showed a strong positive for purified protein derivative (PPD), but only 312 opted for TB preventive treatment. There appeared to be no significant difference in the prevalence of LTBI and TPT rate between male and female students. Concurrently, 11 (71 per 100,000) and 7 (158 per 100,000) cases of active tuberculosis were identified in 6 universities and 6 higher vocational colleges, respectively. Interestingly, almost all freshmen who underwent TPT came from universities, suggesting a statistically significant disparity in TPT rate (χ2 = 139.829, P < 0.001) between these two types of educational institutions. Meanwhile, as for the age-wise distribution of latent infection among 17-20 years old freshmen, the LTBI rate exhibited 10.5%, 11.6%, 12.1% and 13.5%, respectively. Correlation between LTBI rate, the strong positive rate was statistically significant among different ages (χ2 = 34.559, P < 0.001). Over a follow-up period of 2 years, three students were diagnosed with active tuberculosis, one of which was resistant to rifampicin. All three students manifested a strong positive for PPD and declined preventive treatment during TB screening.

CONCLUSIONS

The data indicates a high rate of LTBI amongst students in areas with a heavy TB burden, potentially leading to cross-regional TB transmission due to the migration of students. Education level might contribute to the limited uptake of TPT. Therefore, improving the implementation of TB preventive treatments is crucial in controlling and preventing TB across schools.

Comparing Catastrophic Costs: Active vs. Passive Tuberculosis Case Finding in Urban Vietnam

Active case finding (ACF) is a strategy that aims to identify people with tuberculosis (TB) earlier in their disease. This outreach approach may lead to a reduction in catastrophic cost incurrence (costs exceeding 20% of annual household income), a main target of WHO's End TB Strategy. Our study assessed the socio-economic impact of ACF by comparing patient costs in actively and passively detected people with TB. Longitudinal patient cost surveys were prospectively fielded for people with drug-sensitive pulmonary TB, with 105 detected through ACF and 107 passively detected. Data were collected in four Vietnamese cities between October 2020 and March 2022. ACF reduced pre-treatment (USD 10 vs. 101, p < 0.001) and treatment costs (USD 888 vs. 1213, p < 0.001) in TB-affected individuals. Furthermore, it reduced the occurrence of job loss (15.2% vs. 35.5%, p = 0.001) and use of coping strategies (28.6% vs. 45.7%, p = 0.004). However, catastrophic cost incurrence was high at 52.8% and did not differ between cohorts. ACF did not significantly decrease indirect costs, the largest contributor to catastrophic costs. ACF reduces costs but cannot sufficiently reduce the risk of catastrophic costs. As income loss is the largest driver of costs during TB treatment, social protection schemes need to be expanded.

Evaluating systematic targeted universal testing for tuberculosis in primary care clinics of South Africa: A cluster-randomized trial (The TUTT Trial)

BACKGROUND

The World Health Organization (WHO) recommends systematic symptom screening for tuberculosis (TB). However, TB prevalence surveys suggest that this strategy does not identify millions of TB patients, globally. Undiagnosed or delayed diagnosis of TB contribute to TB transmission and exacerbate morbidity and mortality. We conducted a cluster-randomized trial of large urban and rural primary healthcare clinics in 3 provinces of South Africa to evaluate whether a novel intervention of targeted universal testing for TB (TUTT) in high-risk groups diagnosed more patients with TB per month compared to current standard of care (SoC) symptom-directed TB testing.

METHODS AND FINDINGS

Sixty-two clinics were randomized; with initiation of the intervention clinics over 6 months from March 2019. The study was prematurely stopped in March 2020 due to clinics restricting access to patients, and then a week later due to the Coronavirus Disease 2019 (COVID-19) national lockdown; by then, we had accrued a similar number of TB diagnoses to that of the power estimates and permanently stopped the trial. In intervention clinics, attendees living with HIV, those self-reporting a recent close contact with TB, or a prior episode of TB were all offered a sputum test for TB, irrespective of whether they reported symptoms of TB. We analyzed data abstracted from the national public sector laboratory database using Poisson regression models and compared the mean number of TB patients diagnosed per clinic per month between the study arms. Intervention clinics diagnosed 6,777 patients with TB, 20.7 patients with TB per clinic month (95% CI 16.7, 24.8) versus 6,750, 18.8 patients with TB per clinic month (95% CI 15.3, 22.2) in control clinics during study months. A direct comparison, adjusting for province and clinic TB case volume strata, did not show a significant difference in the number of TB cases between the 2 arms, incidence rate ratio (IRR) 1.14 (95% CI 0.94, 1.38, p = 0.46). However, prespecified difference-in-differences analyses showed that while the rate of TB diagnoses in control clinics decreased over time, intervention clinics had a 17% relative increase in TB patients diagnosed per month compared to the prior year, interaction IRR 1.17 (95% CI 1.14, 1.19, p < 0.001). Trial limitations were the premature stop due to COVID-19 lockdowns and the absence of between-arm comparisons of initiation and outcomes of TB treatment in those diagnosed with TB.

CONCLUSIONS

Our trial suggests that the implementation of TUTT in these 3 groups at extreme risk of TB identified more TB patients than SoC and could assist in reducing undiagnosed TB patients in settings of high TB prevalence.

TRIAL REGISTRATION

South African National Clinical Trials Registry DOH-27-092021-4901.

Number needed to screen for TB in clinical, structural or occupational risk groups

BACKGROUND: Screening for active TB using active case-finding (ACF) may reduce TB incidence, prevalence, and mortality; however, yield of ACF interventions varies substantially across populations. We systematically reviewed studies reporting on ACF to calculate the number needed to screen (NNS) for groups at high risk for TB.METHODS: We conducted a literature search for studies reporting ACF for adults published between November 2010 and February 2020. We determined active TB prevalence detected through various screening strategies and calculated crude NNS for - TB confirmed using culture or Xpert® MTB/RIF, and weighted mean NNS stratified by screening strategy, risk group, and country-level TB incidence.RESULTS: We screened 27,223 abstracts; 90 studies were included (41 in low/moderate and 49 in medium/high TB incidence settings). High-risk groups included inpatients, outpatients, people living with diabetes (PLWD), migrants, prison inmates, persons experiencing homelessness (PEH), healthcare workers, and miners. Screening strategies included symptom-based screening, chest X-ray and Xpert testing. NNS varied widely across and within incidence settings based on risk groups and screening methods. Screening tools with higher sensitivity (e.g., Xpert, CXR) were associated with lower NNS estimates.CONCLUSIONS: NNS for ACF strategies varies substantially between adult risk groups. Specific interventions should be tailored based on local epidemiology and costs.