17.4 Treatment outcomes

 

In principle, the number of patients with an outcome is identical to the number of patients detected during the same period. Any difference requires explanation.

 

Special case of transfers between facilities:

• The receiving facility should transmit the patient’s treatment outcome to the facility that transferred them.
• The transferring facility should include the patient's treatment outcome in its treatment outcome report.

 

For an example of treatment outcome report, see Appendix 37.

17.4.2 Definitions of end-of-treatment outcomes

End-of-treatment outcomes are assigned to all patients with active TB entered into the TB registers.

End-of-treatment outcomes are mutually exclusive and exhaustive. Their definitions are similar for DS-TB and DR-TB.

 

Table 17.6 − End-of-treatment outcomes for active TB (adapted from WHO) [1] Citation 1. World Health Organization. Meeting report of the WHO expert consultation on drug-resistant tuberculosis treatment outcome definitions. 17–19 November 2020. Geneva.
https://apps.who.int/iris/rest/bitstreams/1336957/retrieve

 

 

The end-of-treatment outcome is assigned to each patient for a given TB regimen. This means that if the regimen is changed, the patient is declared "treatment failure" for the initial regimen. They should be re-registered as "previously treated patient" and a new end-of-treatment outcome will be assigned for the new regimen.

 

Notes:

• An outcome "lost to follow-up before treatment" is assigned to patients with TB who did not start treatment within 2 months after diagnosis.
• In addition to the above outcomes, the outcome "treatment success" is calculated by adding the number of patients "cured" and the number of patients "treatment completed".

 

Box 17.1 – Definitions of bacteriological conversion and reversion

 

Bacteriological conversion: 2 consecutive smears (for DS-TB and Hr-TB) or cultures (for MDR/RR-TB) on specimens collected at least 7 days apart are negative. The date of conversion is the specimen collection date of the first negative smear or culture.   Bacteriological reversion: after an initial conversion, 2 consecutive smears (for DS-TB and Hr-TB) or cultures (for MDR/RR-TB) on specimens collected at least 7 days apart are positive. The date of reversion is the specimen collection date of the first positive smear or culture.

 

17.4.3 Definition of post-treatment outcomes

When a long-term follow-up after treatment end is possible for patients with MDR/RR-TB on BPaLM or BPaL regimen a Citation a. The objective is to detect any potential relapses after a short treatment regimen (STR) for which there is still little experience. , a post-treatment outcome "sustained treatment success" b Citation b. For operational research purposes only, this outcome may also be assigned to patients with DS-TB and to patients with DR-TB on other regimens. The criteria are the same as for patients on BPaLM or BPaL regimen, but the outcome for DS-TB is assigned only once (6 months after end of treatment). is assigned to patients meeting the definition below.

 

Box 17.2 – Definition of "sustained treatment success"

 

End-of-treatment outcome: "cured" or "treatment completed" AND No bacteriological reversion (Box 17.1) or clinical signs of relapse 6 and 12 months after end of treatment

 

WHO reports an average success rate of approximately 88% worldwide for patients on DS-TB treatment and 63% for patients on MDR/RR-TB treatment [2] Citation 2. World Health Organization. Global Tuberculosis Report 2023. Geneva: World Health Organization; 2023.
https://www.who.int/teams/global-tuberculosis-programme/tb-reports . However, success rates and data reliability vary considerably between countries.

 

Although there is no universal threshold to define an acceptable proportion of "lost to follow-up", the higher the proportion, the more likely it is that there are significant shortcomings in patient management. Investigations are necessary and corrective measures must be implemented (see Chapter 13).

 

In a large meta-analysis, the proportion of TB patients dying during TB treatment was 3.5% in patients with no HIV infection and 18.8% in patients with HIV infection [3] Citation 3. Straetemans M, Glaziou P, Bierrenbach AL, Sismanidis C, van der Werf MJ (2011). Assessing Tuberculosis Case Fatality Ratio: A Meta-Analysis. PLoS ONE 6(6): e20755.
https://doi.org/10.1371/journal.pone.0020755 . A proportion significantly higher requires explanation (e.g. late detection/enrolment, high proportion of patients with diabetes, high proportion of undetected drug resistance).