Overview of current case and treatment outcome definitions

1. 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

2. Outline • History of case and treatment outcome definitions • Current case definitions and treatment outcome definitions • Commentary on current definitions • Next steps

3. 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

4. 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

5. 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

6. 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

7. 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)

8. 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

9. 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.

10. 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

11. 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