New treatment outcome definitions for drug-susceptible and drug-resistant tuberculosis: update from World Health Organization

<b>Background:</b> Recent developments in TB treatment have prompted the need for revision of the TB treatment outcome definitions. <b>Aims and objectives:</b> The objectives of the WHO consultation were to determine recent changes in TB treatment affecting treatment outcome definitions and discuss options for changing the definitions. <b>Methods:</b> An online expert consultation meeting was organized in November 2020, attended by approximately 70 experts. <b>Results:</b> The consultation led WHO to propose new definitions of TB treatment outcomes. Treatment failed: A patient whose treatment regimen needed to be terminated or permanently changeda to a new regimen or treatment strategy. Cured: A pulmonary TB patient with bacteriologically confirmed TB at the beginning of treatment who completed treatment&nbsp;as recommended by the national policy with evidence of bacteriological response and no evidence of failure. Treatment completed: A patient who completed treatment as recommended by the national policy, whose outcome does not meet the definition for cured or treatment failed. Died: A patient who died before starting treatment or during the course of treatment. Lost: to follow up A patient who did not start treatment or whose treatment was interrupted for 2 consecutive months or more. Not evaluated: A patient for whom no treatment outcome was assigned. Treatment success: The sum of cured and treatment completed. Optional definition for operational research: Sustained treatment success: An individual assessed at 6 months (for DS-TB and DR-TB) and at 12 months (for DR-TB only) after successful TB treatment, who is alive and free of TB. <b>Conclusions:</b> Updated definitions will be adopted by WHO in 2021.