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					        Overview of current case
   and treatment outcome definitions

              Malgosia Grzemska
         TB Operations and Coordination
              Stop TB Department

                             Consultation

Impact of WHO-endorsed molecular diagnostics on TB and MDR-TB case- and
                     treatment outcomes definitions

                        Geneva, 12-13 May 2011
Outline

 History of case and treatment outcome definitions

 Current case definitions and treatment outcome
  definitions

 Commentary on current definitions

 Next steps
            History of case
   and treatment outcome definitions
 First introduced by Karel Styblo in Africa in pilot projects
  of short-course chemotherapy

 Confirmed by WHO in 1994 in the "Framework for
  effective tuberculosis control" and recommended for use
  in DOTS programmes worldwide

 1998 – Europe started revision to facilitate use of culture
  in diagnosis and monitoring

 Each edition of WHO Treatment guidelines – slight
  revision of definitions to "accommodate" new
  developments in TB control
    Current case definitions (WHO)

     Definite TB case
          – A patient with M. tuberculosis complex identified from a clinical
            specimen, either by culture or by a newer method such as
            molecular line probe assay.
          – Pulmonary case with 1 or more initial sputum smear
            examinations positive for acid-fast bacilli (AFB) - in countries
            lacking lab. capacity to routinely identify M. tuberculosis
            complex and with functional EQA system.

     TB case
          – A definite case of TB (as above); but also
          – Patient in whom health worker (clinician or other practitioner)
            has diagnosed TB and decided to treat the patient with the
            whole course of anti-TB treatment

Treatment of tuberculosis: guidelines -- 4th edition, Geneva, WHO, 2009
Current case definitions (WHO) - 2

 Classification according to
   – Anatomical site of disease (P and EP)
   – Bacteriological results (including drug resistance)
      • Culture positive or Culture negative (both P and EP)
      • Smear positive, smear negative, smear not done (only P)
   – History of previous treatment
      • New
      • Previously treated: relapse, failure, default
      • Transfer in
      • Other
   – HIV status
  Commentary on case definitions

 Definite case
   – Smear microscopy not considered confirmatory test (though used
     in resource poor settings)
   – HIV positive patients – often smear negative
   – Culture and newer tests added to "accommodate" availability of
     tools other than smear microscopy

 Previously treated
   – Difference between relapses (new episode - incident) and other
     retreatment's (same episode requiring change of regimen -
     prevalent)
   – Relapse true relapse or re-infection
    Commentary on case definitions (2)

 No one knows what to do with "transfer –in" – not
  evaluated

 Other – no standard interpretation

 No information on groups with high risk of TB – which
  may be required for decision making on appropriate
  diagnostic and prevention intervention

 Disaggregation according to social or other
  determinants does not exist

 No information on co-morbidities (other than HIV)
Current treatment outcome definitions (WHO)

   Cure.
        – A patient whose sputum smear (or culture) was positive at the
          beginning of the treatment but who was smear- (or culture-)
          negative in the last month of treatment and on at least one
          previous occasion.

   Completed.
        – A patient who completed treatment but who does not have a
          negative sputum smear (or culture) result in the last month of
          treatment and on at least one previous occasion.

   Treatment success
        – is the sum of cure and completed.

Treatment of tuberculosis: guidelines -- 4th edition, Geneva, WHO, 2009
 Current treatment outcome definitions (WHO)
 Failure.
   – A patient whose sputum smear (or culture) is positive at 5 months or
     later during treatment.
   – Also included in this definition are patients found to harbour a
     multidrug-resistant (MDR) strain at any point of time during the
     treatment, whether they are smear-negative or -positive

 Default.
   – A patient whose treatment was interrupted for 2 consecutive months
     or more.

 Died.
   – A patient who dies for any reason during the course of treatment

 Transfer out.
   – A patient who has been transferred to another recording and
     reporting unit and whose treatment outcome is unknown.
Commentary on treatment outcome definitions
  Originally only smear positive cases were evaluated

  Addition of "culture"; recommendations to evaluate smear-negative
   and EP cases

  Cure – only for smear positive (and culture positive); Failure – only
   for smear positive (+ culture) and too late into the treatment course

  If Xpert is the initial diagnostic test – less cases would be classified
   cured (treatment monitoring with smear and/or culture)

  Transfer – out – excuse for not following up (often default,
   sometimes death, - but perceived a "better" outcome

  Individual NTPs or regions (EU) revised case-or outcome
   definitions

  Non-evaluated – added for the purpose of global reporting
           Conclusions – next steps

 Transition from DOTS to Stop TB Strategy did not result in
  changes in the definitions

 Programmes add their own modifications, which may create
  confusion and would hamper global reporting

 Introduction of molecular tools in diagnosis of TB requires
  modifications of case definitions and treatment outcome
  definitions, else many cases may be not evaluated

 Preparation for the introduction of new (shorter) treatment
  regimens in the future

				
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