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Improving diagnosis. TB laboratory strengthening . Role of laboratory services in TB control. Laboratory services perform crosscutting activities for the three implementation working groups (DEWG, DOTS-Plus, TB/HIV)

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Improving diagnosis

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Improving diagnosis

TB laboratory strengthening


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Role of laboratory services in TB control

Laboratory services perform crosscutting activities for the three

implementation working groups (DEWG, DOTS-Plus, TB/HIV)

  • Diagnosis of all TB cases (e.g., SM(+), SM (-), extrapulmonary, HIV co-infected, drug resistant)

  • Monitoring patient's response to treatment

  • Participation in TB surveillance; notification/prevalence of TB; DRS

  • Assistance in selecting effective treatment regimens: MDR-TB

  • Human resource development including training

  • Operational research


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Consequences of poor lab performance

  • Unreliable diagnosis results: over/under diagnosing of TB patients

  • Individual level:

    • Undiagnosed TB cases: (disease transmission, death)

    • Mismanagement of patients (MDR-TB)

    • Over diagnosed patients: (bear the effects of long &

      unnecessary treatment, disease stigma)

  • National/Global level:

    • Low case detection,

    • Continuous transmission and

    • Ultimately poorly performing TB control programme


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Situation Analysis (22 HBCs)

  • 18 countries have National Reference Laboratory (NRL) to oversee the organization and performance of the network; however some NRLs are weak and not fully functional

  • 18 HBCs claim to have EQA scheme for smear microscopy; however, majority report it's limited coverage and suboptimal quality

  • 14 countries perform culture at the national/regional level according to nationally-defined specifications, which are not always consistent with international recommendations. In addition, the quality of culture is unknown

  • Major impediments to perform diagnostic tests (especially culture and DST):

    • inadequate equipment and infrastructure

    • limited technical knowledge

    • Insufficient human and financial resources


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Stop TB Strategy and laboratory

  • Pursuing quality DOTS expansion and enhancement

    • Political commitment

    • Case detection through quality-assured bacteriology

    • Standardised treatment, with supervision and patient support

    • Effective drug supply system

    • Monitoring system and impact evaluation

  • Addressing TB/HIV and MDR-TB

  • Contributing to health system strengthening

  • Engaging all care providers

  • Empowering patients and communities

  • Enabling and promoting research


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Improving diagnosis- planning framework

Activities:

  • Organization of TB laboratory network (prevalence and population distribution)

  • Provide laboratory equipment supplies and reagents

  • Implement quality assurance programme for smear microscopy, culture and DST

  • Promote human resource development

  • Meetings and Workshops

  • Support technical assistance

  • Promote operational research

  • Expedite the diagnosis of smear negative & extrapulmonary TB in high HIV prevalence areas


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Peripheral level (Level 1)

  • Located at primary health centers or district hospitals

  • Activities:

    • Sputum collection

    • Smear microscopy

    • Recording and reporting

    • Slide collection for EQA

  • Manpower: ≤ 1(2) worker(s); >2-3 / <20 smears per day

  • Population coverage: 100-200K


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Intermediate level (Level-2)

  • Located at regional health institutions including hospitals

  • Activities:

    • Services to clinics: FM/ZN smear microscopy

    • Culture / ID of MTB; referral services

    • Support activities: (supply of reagents/materials, training; EQA for smear microscopy including supervision)

  • Manpower: 2-3 workers (only for TB work)

  • Population Coverage: 500 - 1,500K


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Central level (Level 3)

  • Part of the central public health laboratory, research laboratory, or upgraded laboratory in the country’s principal tuberculosis institution

  • Activities:

    • National reference laboratory for the TB program,

    • Development of standardized manuals and guidelines

    • Training

    • External Quality Assurance

    • Perform: smear microscopy, culture and DST


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Generally 3 levels in a TB lab network

LEVEL 3

LEVEL 2

LEVEL 1

  • All functions of level 1 and 2

  • Identification of mycobacteria

  • other than MTB

  • DST of M. Tuberculosis

  • laboratory equipment services

  • and maintenance

  • Laboratory manuals and

  • guidelines for all lab services

  • Primary link with NTP

  • Supervision of intermediate QA

  • of culture and microscopy

  • Training of intermediate

  • organization of DRS

  • Operational and applied research

  • All functions of level 1

  • fluorescence microscopy (optional)

  • Digestion and decontamination

  • of specimens

  • Culture and identification of MTB

  • Training of staff

  • Support and supervision of

  • peripheral staff for microscopy

  • Preparation and distribution

  • of reagents

  • QA and panel testing of

  • microscopy

  • Manpower: 2-3 only for TB

  • Coverage: 500K-1.500K

  • Receipt of specimens

  • Preparation and staining

  • of smears

  • ZN microscopy /recording

  • Reporting of results

  • Maintenance of lab register

  • Management of reagents

  • and supplies

  • Internal QC

  • Participation in EQA system

    Manpower: 1-2 staff

    Coverage: 100-200K

Internal and External Quality Assurance at all levels


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External Quality Assessment

  • Early warning-system for problems

  • Measure of laboratory quality

  • Valuable benchmarking tool (standardization and traceability)

  • Indicator of where to direct improvement efforts

  • Monitor of changes in technology and testing practices (evaluation component)


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Quality Assurance Programme Components

  • Supervision

  • Rechecking/panel testing

  • Internal quality control


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Strengthen the national capacity to perform

culture for diagnostic purposes


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Epidemiological and programmatic conditions have changed

  • The number of repeatedly sputum negative TB cases is increasing,

    mainly due to the HIV epidemic

  • Many countries are implementing DRS and monitoring MDR trends

  • Second line drugs are available and a growing number of countries

    implement DOTS-Plus strategy

  • Culture is increasingly used even in resource limited countries


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Estimated cost of culture (LJ method) & DST (proportion method) per laboratory

  • Capital investment per laboratory: 200,000$US

  • Consumables, media and pure substances for 1000 cultures and DST: 22,000$US

  • Training: national & international: 20,000$US

  • EQA for culture and DST: 5,000$US/ year

  • Staff salaries


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Proposed approach to strengthen capacity to perform culture

  • Develop/strengthen the capacity to perform culture at theintermediate level as an essential component of DOTS expansion

  • Initially, 1 culture facility should be established per ~ 3 to 5 million population

  • Introducing culture in step wise approach to cover all eligible population by 2015 (number of facilities will depend on the national policy)


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Smear microscopy optimizations

Outcomes of expert consultation meeting (1-2 September 2005)

The meeting was organized to discuss the outcomes of the systematic

literature review to determine the strength of existing data, identify

knowledge gaps, and define a research agenda regarding the following

issues:

  • Fluorescence microscopy (45 studies)

  • Sputum processing methods (83 studies)

  • Number of sputum smears per TB suspect (41 studies)


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Fluorescent microscopy (FM)

Findings:

  • Improve the sensitivity of sputum microscopy by 10%

  • Shorten time of diagnosis

  • Reduce laboratory workload; FM recommended to be used in high volume settings >100 smears

    Recommendations:

  • Countries wishing to implement FM at the peripheral level, in lower volume settings, should do so within the context of operational research

  • FM may be considered at all levels in high HIV prevalence countries

    Collaboration with TDR, FIND on operation research to further

    evaluate applicability, sustainability of this technology


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Fluorescent microscopy

Close collaboration with FIND and WHO on evaluation

of the LED portable fluorescent microscope


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Sputum processing methods

Findings:

  • Use of different chemicals and methodology

  • Moderate sensitivity improvement

  • Serious concerns regarding the use of centrifuge and bio-safety issues

    Recommendations:

  • Concentration methods not recommended

  • Sedimentation may be promising and less problematic to implement; however, multi-centre studies are required to investigate the performance and feasibility with standardised method

    Collaboration with TDR and FIND on design and implementation of

    operational research to evaluate sedimentation methods.


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Number of sputum smears per TB suspect

Findings:

  • The results indicated limited incremental yield of the 3rd sputum examination (2-5%)

  • However, there was some bias in studies design and difference in case definition

    Points to be considered:

  • Dilemma on improving sensitivity (more false positive) or specificity

  • Workload issues (more time allocation for examination of slide => improved output)

    Recommendation:

    The questions should be studied in the context of case definition (this topic will be

    presented and discussed during the upcoming STAG meeting)


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