Impact and cost-effectiveness of the 6-month BPaLM regimen for rifampicin-resistant tuberculosis in Moldova: A mathematical modeling analysis

BACKGROUND

Emerging evidence suggests that shortened, simplified treatment regimens for rifampicin-resistant tuberculosis (RR-TB) can achieve comparable end-of-treatment (EOT) outcomes to longer regimens. We compared a 6-month regimen containing bedaquiline, pretomanid, linezolid, and moxifloxacin (BPaLM) to a standard of care strategy using a 9- or 18-month regimen depending on whether fluoroquinolone resistance (FQ-R) was detected on drug susceptibility testing (DST).

METHODS AND FINDINGS

The primary objective was to determine whether 6 months of BPaLM is a cost-effective treatment strategy for RR-TB. We used genomic and demographic data to parameterize a mathematical model estimating long-term health outcomes measured in quality-adjusted life years (QALYs) and lifetime costs in 2022 USD ($) for each treatment strategy for patients 15 years and older diagnosed with pulmonary RR-TB in Moldova, a country with a high burden of TB drug resistance. For each individual, we simulated the natural history of TB and associated treatment outcomes, as well as the process of acquiring resistance to each of 12 anti-TB drugs. Compared to the standard of care, 6 months of BPaLM was cost-effective. This strategy was estimated to reduce lifetime costs by $3,366 (95% UI: [1,465, 5,742] p < 0.001) per individual, with a nonsignificant change in QALYs (-0.06; 95% UI: [-0.49, 0.03] p = 0.790). For those stopping moxifloxacin under the BPaLM regimen, continuing with BPaL plus clofazimine (BPaLC) provided more QALYs at lower cost than continuing with BPaL alone. Strategies based on 6 months of BPaLM had at least a 93% chance of being cost-effective, so long as BPaLC was continued in the event of stopping moxifloxacin. BPaLM for 6 months also reduced the average time spent with TB resistant to amikacin, bedaquiline, clofazimine, cycloserine, moxifloxacin, and pyrazinamide, while it increased the average time spent with TB resistant to delamanid and pretomanid. Sensitivity analyses showed 6 months of BPaLM to be cost-effective across a broad range of values for the relative effectiveness of BPaLM, and the proportion of the cohort with FQ-R. Compared to the standard of care, 6 months of BPaLM would be expected to save Moldova's national TB program budget $7.1 million (95% UI: [1.3 million, 15.4 million] p = 0.002) over the 5-year period from implementation. Our analysis did not account for all possible interactions between specific drugs with regard to treatment outcomes, resistance acquisition, or the consequences of specific types of severe adverse events, nor did we model how the intervention may affect TB transmission dynamics.

CONCLUSIONS

Compared to standard of care, longer regimens, the implementation of the 6-month BPaLM regimen could improve the cost-effectiveness of care for individuals diagnosed with RR-TB, particularly in settings with a high burden of drug-resistant TB. Further research may be warranted to explore the impact and cost-effectiveness of shorter RR-TB regimens across settings with varied drug-resistant TB burdens and national income levels.

The recent rapid expansion of multidrug resistant Ural lineage Mycobacterium tuberculosis in Moldova

The projected trajectory of multidrug resistant tuberculosis (MDR-TB) epidemics depends on the reproductive fitness of circulating strains of MDR M. tuberculosis (Mtb). Previous efforts to characterize the fitness of MDR Mtb have found that Mtb strains of the Beijing sublineage (Lineage 2.2.1) may be more prone to develop resistance and retain fitness in the presence of resistance-conferring mutations than other lineages. Using Mtb genome sequences from all culture-positive cases collected over two years in Moldova, we estimate the fitness of Ural (Lineage 4.2) and Beijing strains, the two lineages in which MDR is concentrated in the country. We estimate that the fitness of MDR Ural strains substantially exceeds that of other susceptible and MDR strains, and we identify several mutations specific to these MDR Ural strains. Our findings suggest that MDR Ural Mtb has been transmitting efficiently in Moldova and poses a substantial risk of spreading further in the region.

Identifying local foci of tuberculosis transmission in Moldova using a spatial multinomial logistic regression model

BACKGROUND

Multidrug resistant tuberculosis (MDR-TB) represents a major public health concern in the Republic of Moldova, with an estimated 31% of new and 56% of previously treated TB cases having MDR disease in 2022. A recent genomic epidemiology study of incident TB occurring in 2018 and 2019 found that 92% of MDR-TB was the result of transmission. The MDR phenotype was concentrated among two M. tuberculosis (Mtb) lineages: L2.2.1 (Beijing) and L4.2.1 (Ural).

METHODS

We developed and applied a hierarchical Bayesian multinominal logistic regression model to Mtb genomic, spatial, and epidemiological data collected from all individuals with diagnosed TB in Moldova in 2018 and 2019 to identify locations in which specific Mtb strains are being transmitted. We then used a logistic regression model to estimate locality-level factors associated with local transmission.

FINDINGS

We found differences in the spatial distribution and degree of local concentration of disease due to specific strains of Beijing and Ural lineage Mtb. Foci of transmission for four strains of Beijing lineage Mtb, predominantly of the MDR-TB phenotype, were located in several regions, but largely concentrated in Transnistria. In contrast, transmission of Ural lineage Mtb had less marked patterns of spatial aggregation, with a single strain (also of the MDR phenotype) spatially clustered in southern Transnistria. We found a 30% (95% credible interval 2%-80%) increase in odds of a locality being a transmission cluster for each increase of 100 persons per square kilometer, while higher local tuberculosis incidence and poverty were not associated with a locality being a transmission focus.

INTERPRETATION

Our results identified localities where specific Mtb transmission networks were concentrated and quantified the association between locality-level factors and focal transmission. This analysis revealed Transnistria as the primary area where specific Mtb strains (predominantly of the MDR-TB phenotype) were locally transmitted and suggests that targeted intensified case finding in this region may be an attractive policy option.

FUNDING

Funding for this work was provided by the National Institute of Allergy and Infectious Diseases at the US National Institutes of Health.

Predicting stringent QuantiFERON-TB Gold Plus conversions in contacts of tuberculosis patients

OBJECTIVES

To assess associations between disease severity in index TB patients and QuantiFERON-TB Gold Plus (QFT-Plus) results in contacts, and predictors for QFT-Plus conversion in contacts over 6-12 months.

METHODS

TB patients (n = 295) and the contacts (n = 1051) were enrolled during 2018-2021 with QFT-Plus performed at baseline and months 6 and 12. A strong CD8 response was defined as TB2 interferon gamma (IFN-γ) response minus TB1 >0.6 IU/ml and stringent conversion as change from QFT-plus negative to high-positive QFT-Plus (TB1 or TB2 IFN-γ responses >0.7 IU/ml).

RESULTS

Contacts with index TB patients with sputum smear >1+ was associated with positive QFT-Plus compared to those without (p < 0.001). Contacts with index TB patients with bilateral lung disease were more likely to have strong CD8 responses than those without (p = 0.038). QFT-Plus stringent conversion occurred in 9.7% of contacts over 6-12 months. A TB1 IFN-γ response ≥0.03 IU/ml combined with a TB2 ≥0.06 IU/ml was predictive of a 19-fold increased risk for QFT-Plus stringent conversion in contacts (odd ratio 19.565 [8.484-45.116], p < 0.001).

CONCLUSION

Bacterial burden and bilateral lung disease of index TB patients were associated with positive QFT-Plus and strong CD8 responses in contacts. TB1 and TB2 IFN-γ responses were synergistically predictive of stringent conversion in contacts.

Clinical Evaluation of the XDR-LFC Assay for the Molecular Detection of Isoniazid, Rifampin, Fluoroquinolone, Kanamycin, Capreomycin, and Amikacin Drug Resistance in a Prospective Cohort

While the goal of universal drug susceptibility testing has been a key component of the WHO End TB Strategy, in practice, this remains inaccessible to many. Rapid molecular tests for tuberculosis (TB) and antituberculosis drug resistance could significantly improve access to testing. In this study, we evaluated the accuracy of the Akonni Biosystems XDR-TB (extensively drug-resistant TB) TruArray and lateral-flow-cell (XDR-LFC) assay (Akonni Biosystems, Inc., Frederick, MD, USA), a novel assay that detects mutations in seven genes associated with resistance to antituberculosis drugs: katG, the inhA promoter, and the ahpC promoter for isoniazid; rpoB for rifampin; gyrA for fluoroquinolones; rrs and the eis promoter for kanamycin; and rrs for capreomycin and amikacin. We evaluated assay performance using direct sputum samples from 566 participants recruited in a prospective cohort in Moldova over 2 years. The sensitivity and specificity against the phenotypic reference were both 100% for isoniazid, 99.2% and 97.9% for rifampin, 84.8% and 99.1% for fluoroquinolones, 87.0% and 84.1% for kanamycin, 54.3% and 100% for capreomycin, and 79.2% and 100% for amikacin, respectively. Whole-genome sequencing data for a subsample of 272 isolates showed 95 to 99% concordance with the XDR-LFC-reported suspected mutations. The XDR-LFC assay demonstrated a high level of accuracy for multiple drugs and met the WHO's minimum target product profile criteria for isoniazid and rifampin, while the sensitivity for fluoroquinolones and amikacin fell below target thresholds, likely due to the absence of a gyrB target in the assay. With optimization, the XDR-LFC shows promise as a novel near-patient technology to rapidly diagnose drug-resistant tuberculosis.

Budget impact of next-generation sequencing for diagnosis of TB drug resistance in Moldova

BACKGROUND Diagnosing drug resistance is critical for choosing effective TB treatment regimens. Next-generation sequencing (NGS) represents an alternative approach to conventional phenotypic drug susceptibility testing (pDST) for diagnosing TB drug resistance.METHODS We undertook a budget impact analysis estimating the costs of introduction and routine use of NGS in the Moldovan National TB Programme. We conducted an empirical costing study and collated price and operating characteristics for NGS platforms. We examined multiple NGS scenarios in comparison to the current approach (pDST) for pre-treatment drug resistance testing over 2021-2025.RESULTS Annual testing volume ranged from 912 to 1,926 patients. For the pDST scenario, we estimated total costs of US$362,000 (2021 USD) over the 5-year study period. Total costs for NGS scenarios ranged from US$475,000 to US$1,486,000. Lowest cost NGS options involved targeted sequencing as a replacement for pDST, and excluded individuals diagnosed as RIF-susceptible on Xpert^® MTB/RIF. For all NGS scenarios, the majority (55-80%) of costs were devoted to reagent kits. Start-up costs of NGS were small relative to routine costs borne each year.CONCLUSION NGS adoption will require expanded resources compared to conventional pDST. Further work is required to better understand the feasibility of NGS in settings such as Moldova.

Predicting resistance to fluoroquinolones among patients with rifampicin-resistant tuberculosis using machine learning methods

Background

Limited access to drug-susceptibility tests (DSTs) and delays in receiving DST results are challenges for timely and appropriate treatment of multi-drug resistant tuberculosis (TB) in many low-resource settings. We investigated whether data collected as part of routine, national TB surveillance could be used to develop predictive models to identify additional resistance to fluoroquinolones (FLQs), a critical second-line class of anti-TB agents, at the time of diagnosis with rifampin-resistant TB.

Methods and findings

We assessed three machine learning-based models (logistic regression, neural network, and random forest) using information from 540 patients with rifampicin-resistant TB, diagnosed using Xpert MTB/RIF and notified in the Republic of Moldova between January 2018 and December 2019. The models were trained to predict the resistance to FLQs based on demographic and TB clinical information of patients and the estimated district-level prevalence of resistance to FLQs. We compared these models based on the optimism-corrected area under the receiver operating characteristic curve (OC-AUC-ROC). The OC-AUC-ROC of all models were statistically greater than 0.5. The neural network model, which utilizes twelve features, performed best and had an estimated OC-AUC-ROC of 0.87 (0.83,0.91), which suggests reasonable discriminatory power. A limitation of our study is that our models are based only on data from the Republic of Moldova and since not externally validated, the generalizability of these models to other populations remains unknown.

Conclusions

Models trained on data from phenotypic surveillance of drug-resistant TB can predict resistance to FLQs based on patient characteristics at the time of diagnosis with rifampin-resistant TB using Xpert MTB/RIF, and information about the local prevalence of resistance to FLQs. These models may be useful for informing the selection of antibiotics while awaiting results of DSTs.

Phylogeography and transmission of M. tuberculosis in Moldova: A prospective genomic analysis

BACKGROUND

The incidence of multidrug-resistant tuberculosis (MDR-TB) remains critically high in countries of the former Soviet Union, where >20% of new cases and >50% of previously treated cases have resistance to rifampin and isoniazid. Transmission of resistant strains, as opposed to resistance selected through inadequate treatment of drug-susceptible tuberculosis (TB), is the main driver of incident MDR-TB in these countries.

METHODS AND FINDINGS

We conducted a prospective, genomic analysis of all culture-positive TB cases diagnosed in 2018 and 2019 in the Republic of Moldova. We used phylogenetic methods to identify putative transmission clusters; spatial and demographic data were analyzed to further describe local transmission of Mycobacterium tuberculosis. Of 2,236 participants, 779 (36%) had MDR-TB, of whom 386 (50%) had never been treated previously for TB. Moreover, 92% of multidrug-resistant M. tuberculosis strains belonged to putative transmission clusters. Phylogenetic reconstruction identified 3 large clades that were comprised nearly uniformly of MDR-TB: 2 of these clades were of Beijing lineage, and 1 of Ural lineage, and each had additional distinct clade-specific second-line drug resistance mutations and geographic distributions. Spatial and temporal proximity between pairs of cases within a cluster was associated with greater genomic similarity. Our study lasted for only 2 years, a relatively short duration compared with the natural history of TB, and, thus, the ability to infer the full extent of transmission is limited.

CONCLUSIONS

The MDR-TB epidemic in Moldova is associated with the local transmission of multiple M. tuberculosis strains, including distinct clades of highly drug-resistant M. tuberculosis with varying geographic distributions and drug resistance profiles. This study demonstrates the role of comprehensive genomic surveillance for understanding the transmission of M. tuberculosis and highlights the urgency of interventions to interrupt transmission of highly drug-resistant M. tuberculosis.

Molecular Detection of Mycobacterium tuberculosis in Oral Mucosa from Patients with Presumptive Tuberculosis

Tuberculosis (TB) diagnosis is increasingly based on the detection of Mycobacterium tuberculosis complex (MTBC) DNA in sputum using molecular diagnostic tests as the first test for diagnosis. However, sputum can be difficult to obtain in children, patients without productive cough, and the elderly and approaches testing non-sputum samples are needed. We evaluated whether TB can be detected from the oral mucosa of patients with TB. Adults with presumptive TB were examined using culture, Xpert MTB/RIF, smear microscopy and X-Rays. Oral mucosa swabs collected on PrimeStore-MTM, stored at room temperature if tested within 30 days or at -20 °C if examined at a later time. RT-PCR was performed to detect M. tuberculosis DNA. Eighty patients had bacteriologically-confirmed TB, 34 had bacteriologically-negative TB (negative tests but abnormal X-rays) and 152 were considered not to have TB (not TB). Oral swabs RT-PCR were positive in 29/80 (36.3%) bacteriologically-confirmed, 9/34 (26.5%) bacteriologically-negative and 29/152 (19.1%) not TB. The yield varied among samples stored for less and more than 30 days (p = 0.013) from 61% (11/18) and 29% (18/62) among bacteriologically confirmed, and 30.8% (4/13) and 23.8% (5/21) among bacteriologically-negative participants. Among not TB patients, the specificity was 80.9% (123/152), being 78.3% (18/23) among samples stored less than 30 days and 81.4% (105/129) among samples stored for more than 30 days (p = 0.46). The detection of M. tuberculosis in oral mucosa samples is feasible, but storage conditions may affect the yield.

[Prevention of chronic venous disease: which advice for our patients?]

Chronic venous disease (CVD) is a major public health problem due to its high prevalence and socioeconomic costs. In absence of adequate care, it can lead to chronic venous insufficiency (CVI). Disturbed venous-flow patterns lead to venous hypertension. Therefore, prevention of CVD involves venous hypertension reduction. In primary prevention, it is essential to inform the patient about necessary lifestyle changes. In case of CVD, it is essential to propose treatment (compression, venoactive drugs, and interventional treatments) to avoid CVI appearance and eventually offer the best therapy solutions for CVI complications.

[Vascular follow up in patients suffering from peripheral arterial disease and undergoing revascularization]

The rapid evolution of revascularization techniques has allowed an improvement in quality of life of patients with peripheral artery disease. The angiological follow-up aims to insure durable results of revascularization, to diminish risk of amputation and to limit progression of atheroma plaques. The patient history and physical examination are essential in evaluating impact of peripheral artery disease upon quality of life and insuring the appropriate control of cardiovascular risk factors.

[Measurement of ventricular twist by 2D speckle tracking early after acute myocardial infarction. Comparison between anterior and inferior infarction]

INTRODUCTION

Left Ventricular twist (LV twist) is defined as the apical counter-clockwise rotation relative to the clockwise basal rotation. It has been shown that LV twist decreases after myocardial infarction (MI) and that it is well correlated with left ventricular ejection fraction. Most studies have only evaluated anterior wall MI. The aim of our study was to determine whether LV twist is dependent on the infarct territory (anterior vs. inferior) and whether there is a correlation between LV twist and matrix metalloproteinase-9, a marker of LV remodeling.

METHODS

We measured LV twist using echocardiography with 2D speckle tracking in patients with acute MI and in a control group.

RESULTS

We evaluated 27 controls and 35 patients with acute MI, 15 with anterior wall and 20 with inferior wall MI. LV twist was significantly decreased after MI, compared to the control group (10.93 +/- 2.05 vs 15.5 +/- 2.29; p = 0.003). There was no difference between anterior and inferior MI. LV rotation was decreased in the infarct area. We did not observe a correlation between LV twist and MMP-9, or creatine phosphokinase.

CONCLUSION

With this study we confirm that LV twist decreases after acute MI. Moreover, we show that LV apical rotation is mostly decreased after large anterior MI. As apical rotation is important for ejection and aspiration (untwisting), this could be a possible mechanism of LV dysfunction after MI.

Long QT syndrome in a patient with allergic rhinoconjunctivitis and auto-immune diabetes: focus on the choice of anti-H1 drugs

The long QT syndrome is a rare disease. The prevalence is estimated at 1/5 000 to 1/20,000. Numerous drugs are contra-indicated because they can lengthen the QT interval. A case of pollen allergy in an adolescent with LQTS is described. The possibility to prescribe anti-H1 drugs is reviewed since cases of torsades de pointe and even deaths have been reported for terfenadine and astemizole. Diphenhydramine, orphenadrine and hydroxyzine are contra-indicated. No accidents and no effects on the QT interval have been published for ebastine, fexofenadine, desloratadine and levocetirizine. These anti-H1 drugs could be used with great care, without any association with drugs resulting in low serum potassium level. Azelastine eye drops have been authorized and a routine protection by inhaled corticosteroids during the pollinic period has been advised in this adolescent treated by betablockers.

[Association of Wolff-Parkinson-White syndrome with isolated non-compaction of the left ventricle: a case report]

The Wolff-Parkinson-White syndrome (WPW) may be associated with a number of cardiac pathologies, especially congenital disease, in 7.5 to 17% of cases. The authors report a rare association of the WPW syndrome with two Kent bundles, right and left septal, with non-compaction of the left ventricle in a 52 year old man. This was a chance finding during systematic echocardiography after ablation, and confirmed by cardiac MRI. The patient was asymptomatic.

[Contribution of EKG-gated multislice CT in the diagnosis of arrhythmogenic right ventricle dysplasia: report of two selected cases]

Arrhythmogenic cardiomyopathy of the right ventricle is characterized by replacement of right myocardial cells by fibro-fatty tissue and arrhythmias. The authors present two cases where EKG gated multislice CT was valuable. In one case, comprehensive evaluation of extensive ventricular dysplasia complicated by intraventricular thrombus was achieved whereas accurate evaluation of the ventricular wall process was possible in another case.

[Evaluation of ventricular asynchronism by Doppler tissue imaging in patients with idiopathic dilated cardiomyopathy]

OBJECTIVES

To study ventricular asynchronism with tissue Doppler imaging in patients with primitive dilated cardiomyopathy and narrow QRS.

PATIENTS AND METHODS

We compared a group of patients with DCM and QRS < 120 ms (gr 1, n=25, 52+/-14 yrs, LVEF: 25+/-9%) with a group of normal patients (gr 2, n=16, 36+/-20 yrs). We measured the delays between the beginning of QRS and the beginnings of aortic (QA), mitral (QM), tricuspid (QT) and pulmonary (QP) flows, and of systolic (QSm) and protodiastolic (QEm) wall motion waves recorded with TDI in the basal portion of interventricular septum (IVS) and LV and RV free walls. We then calculated the differences QA-QP, QM-QT, the interparietal differences for QSm and QEm, and the maximal interparietal systolic (QSm max) and diastolic (QEm max) delays.

RESULTS

QA, QP, QM and QT were significantly lengthened in group 1 patients but there were no difference between both groups for QA-QP and QM-QT. There was a trend toward a lengthening of QSm and QEm in group 1 patients. Interparietal differences of QSm and QEm were similar in both groups; however, QSm max and QEm max were significantly longer in group 1 patients than in group 2.

CONCLUSION

Doppler study of patients with DCM and narrow QRS shows a lengthening of all electromechanical delays and suggests some degree of ventricular asynchronism by showing a significant increase in maximal interparietal systolic and diastolic delays.

[Cardiac stimulation in the infant and young child]

This study evaluates the problems and the evolution of cardiac stimulation in infants (aged < 3.5 years) by comparing the endocavity and epicardial routes in a retrospective series of 37 patients. Thirty seven patients aged 1.2 +/- 0.9 years treated with epicardial (n = 19) or endocavity (n = 18) stimulation were followed for 10.9 +/- 6.4 years (0.75-24). The 2 patient groups did not differ in age or weight. Four patients were lost to follow up, and 1 died. The functional duration of the first stimulator was not significantly different if the initial approach was epicardial or endocavity. The endocavity probes were introduced by venous denudation in 15 cases and by subclavian puncture in 3 cases. Fourteen of the 19 children fitted by the epicardial route went on to endocavity stimulation, of which 10 were at the first replacement. None of the 18 patients fitted by the endocavity route went on to epicardial stimulation. Out of 11 endocavity probe replacements and 9 atrialisations, the homolateral venous approach was always possible except in 2 cases. In conclusion, the results for the epicardial and endocavity routes are comparable. For technical reasons (calibre of the veins, size of the stimulator) it would appear reasonable if the endocavity route was used, making do initially with a mono chamber stimulation. The advances in the epicardial electrodes abolishes the major handicap (threshold elevation) of this approach which can be advocated when double chamber stimulation seems preferable.