RESUMEN

BACKGROUND: The development of new diagnostic tools allows for faster detection of both tuberculosis (TB) and multidrug-resistant (MDR) TB and should lead to reduced transmission by earlier initiation of anti TB therapy. The research conducted in the Arkhangelsk region of the Russian Federation in 2012-14 included economic evaluation of Line Probe Assay (LPA) implementation in MDR-TB diagnostics compared to existing culture-based diagnostics of Löwenstein Jensen (LJ) and BacTAlert. Clinical superiority of LPA was demonstrated and results were reported elsewhere. STUDY AIM: The PROVE-IT Russia study aimed to report the outcomes of the cost minimization analysis. METHODS: Costs of LPA-based diagnostic algorithm (smear positive (SSm+) and for smear negative (SSm-) culture confirmed TB patients by Bactec MGIT or LJ were compared with conventional culture-based algorithm (LJ-for SSm- and SSm+ patients and BacTAlert-for SSm+ patients). Cost minimization analysis was conducted from the healthcare system, patient and societal perspectives and included the direct and indirect costs to the healthcare system (microscopy and drug susceptibility test (DST), hospitalization, medications obtained from electronic medical records) and non-hospital direct costs (patient's travel cost, additional expenses associated with hospitalization, supplementary medicine and food) collected at the baseline and two subsequent interviews using the WHO-approved questionnaire. RESULTS: Over the period of treatment the LPA-based diagnostic corresponded to lesser direct and indirect costs comparing to the alternative algorithms. For SSm+ LPA-based diagnostics resulted in the costs 4.5 times less (808.21 US$) than LJ (3593.81 US$) and 2.5 times less than BacTAlert liquid culture (2009.61 US$). For SSm- LPA in combination with Bactec MGIT (1480.75 US$) vs LJ (1785.83 US$) showed the highest cost minimization compared to LJ (2566.09 US$). One-way sensitivity analyses of the key parameters and threshold analyses were conducted and demonstrated that the results were robust to variations in the cost of hospitalization, medications and length of stay. CONCLUSION: From the perspective of Russian Federation healthcare system, TB diagnostic algorithms incorporating LPA method proved to be both more clinically effective and less expensive due to reduction in the number of hospital days to the correct MDR-TB diagnosis and treatment initiation. LPA diagnostics comparing conventional culture diagnostic algorithm MDR-TB was a cost minimizing strategy for both patients and healthcare system.

Asunto(s)

RESUMEN

BACKGROUND: This study describes an outbreak of tuberculosis (TB) in a nursing home for men with mental disorders where residency is lengthy or permanent. This type of setting can provide a model of transmission as contact with the rest of society is extremely limited. AIM: To determine if cases of TB, diagnosed around the same time and in the same place, are linked based on results using molecular and conventional methods. METHODS: The strains of Mycobacterium tuberculosis were analysed by drug resistance testing and mycobacterial interspersed repetitive units-variable number tandem repeats (MIRU-VNTRV). Microbiological results were related to clinical history and time of diagnosis. FINDINGS: Nine patients were diagnosed with TB, and strains were recovered from seven of these patients. Unexpectedly, the strains with the same genotype showed different patterns of resistance, and only two strains demonstrated identical patterns. MIRU-VNTR analysis demonstrated that one patient was infected with two different strains. CONCLUSION: Variation between the strains indicates that the outbreak may have arisen from several sources of infection. The variation in resistance indicates that rapid emergence of antimicrobial resistance is possible. As such, several questions are raised concerning source of infection, development of disease, resistance and mixed infections.

Asunto(s)

RESUMEN

The need for a strong and comprehensive evidence base to support decision making with regard to the implementation of new and improved diagnostic tools and approaches has been highlighted by a number of stakeholders; these include members of the New Diagnostics Working Group (NDWG) and the Subgroup for Introducing New Approaches and Tools of the Stop TB Partnership. To compile such evidence in a systematic manner, we have developed an impact assessment framework (IAF) which links evidence on inputs to outcomes. The IAF comprises five interconnected layers: effectiveness analysis, equity analysis, health systems analysis, scale-up analysis and policy analysis. It can be used by new diagnostics developers and other interested research teams to collect as much policy-relevant data as possible prior to, during and after the demonstration phase of tool development. The evidence collated may be used by international and national policy makers to support adoption, implementation and scale-up decisions. The TREAT TB (Technology, Research, Education and Technical Assistance for TB) initiative uses the IAF in its operational research and field evaluations of new tools and approaches for TB diagnosis. It has also been incorporated into the NDWG's recent publication: 'Pathways to better diagnostics for tuberculosis: a blueprint for the development of TB diagnostics'. This article describes the IAF and the process of improving it and suggests next steps in overcoming the challenges in its implementation.

Asunto(s)

RESUMEN

An analytical solution for the radiation emitted from a dipole embedded in an arbitrary, planar dielectric film stack is presented. The calculation uses a rigorous Hertz-vector formalism to treat the electromagnetic boundary conditions. The radiation fields are then evaluated in a far-field approximation to get the radiated fields far from the dipole. Both two-dimensional (2D) emission into bound modes of the dielectric stack and three-dimensional (3D) emission into radiation fields above and below the stack are evaluated. These solutions are explored for two simple cases: a InGaAs slab symmetrically clad with up to four high-contrast (Al(2)O(3)/GaAs) Bragg mirror pairs and semi-infinite air spaces, and a similar asymmetric structure with a GaAs substrate on one side. The symmetric structure supports both 2D bound and 3D radiation fields. The asymmetric structure only supports 3D radiation fields since there are no strictly bound modes, but "leaky" modes appear that are very similar to the bound modes in the symmetric structure except that the radiated power ultimately is transmitted into the substrate in a very highly directional beam. This calculation is applicable to a wide range of solid-state photonic devices, including vertical-cavity and edge-emitting lasers, spontaneous light-emitting diodes, and photodetectors.