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Percent Bacteriologically Confirmed

References in the content below refer to the PBMEF Guide.

Definitions

Percent of people with new and relapse pulmonary TB who are bacteriologically confirmed. Bacteriologically confirmed: Smear positive for TB or culture positive for TB or positive for TB by a World Health Organization-recommended rapid diagnostics test (WRD): FluoroType® MTBDR (Hain), Loopamp™ MTBC detection kit (TB-LAMP), Xpert® MTB/RIF, Xpert® MTB/RIF Ultra, Truenat® MTB or MTB Plus, RealTime MTB (Abbott), BD MAX™ MDR-TB, cobas® MTB (Roche), or LF-LAM.

Note: LF-LAM is included as a recommended TB test for people living with HIV (PLHIV). LF-LAM is not recommended to confirm TB in all populations and notably should not be used in outpatient settings for adults, adolescents, and children without symptoms of TB or in those with a CD4 count > 200 cells/mm3. At the time of this publication, Alere Determine™ TB LAM Ag is the only commercially available LF-LAM test. Full guidance on the use of LF-LAM can be found at: https://www.who.int/publications/i/item/9789241550604.

Calculation: (Numerator/Denominator) x 100

Numerator

Number of new and relapse bacteriologically confirmed pulmonary TB notifications (smear positive or culture positive or positive by WHO-recommended rapid diagnostics test [WRD]) during the reporting period.

Denominator

Number of people with new and relapse pulmonary TB (bacteriologically confirmed plus clinically diagnosed) during the reporting period.
Ref #
BAC_CON
(Previously DT-12)
Tier Level
Core Indicator
Category
Reach
Type
Core Outcome
Unit of Measure
Percent of people
Data Type
Percentage
Disaggregations
Age (0–4, 5–14, 15+)
Sex
HIV Status
Reporting Level
All Core PBMEF indicators should be reported at the national level; data may also be collected subnationally for more granular monitoring.
Reporting Frequency
This indicator should be reported on a semiannual basis at a minimum. More frequent monitoring on a quarterly, monthly, or real-time basis is recommended. Performance plans and reports (PPRs) for this indicator are based on calendar year (CY) periodicity to reflect national level attainment and align with the USAID congressional reporting requirements.

Both the numerator and denominator are reported from National TB Program (NTP) official records. Quarterly report on TB case registration in the basic management unit.

This standard WHO indicator can also be calculated using data from the WHO TB database. The variables for the numerator are: new_labconf plus ret_rel_labconf. The variables for the denominator are: new_clindx plus ret_rel_clindx plus new_labconf plus ret_rel_labconf.

As countries intensify efforts to improve TB diagnosis and treatment and close case detection gaps, the percent of people with notified TB that are bacteriologically confirmed should be monitored to ensure that people are correctly diagnosed and initiated on the most effective treatment regimen as early as possible. This indicator measures the strength of the diagnostic and laboratory system, and the TB program’s capacity to establish TB diagnosis by bacteriological confirmation of Mtb. Specifically, USAID is supporting introduction, scale up, and quality implementation of new and existing diagnostic methods, including access to WRDs in countries that receive TB funding.

Globally, in 2021, only 75% of pulmonary TB was bacteriologically confirmed, an increase from 57% in 2019 and 56% in 2017. The End TB Strategy has set a target of 90% bacteriological confirmation of new TB diagnoses and 95% of relapse diagnoses by 2025. Greater efforts are needed to improve the availability and use of the most sensitive diagnostic tests for TB and to ensure that international standards for TB care are met to avoid missed diagnoses of people who have TB, overtreatment of people who do not have TB, and efficient use of resources.

A high bacteriological diagnosis coverage reflects multiple processes, including availability and access to adequate bacteriological diagnostic services (trained staff, equipment, etc.), quality of laboratory testing, and adherence to TB guidelines.

Bacteriological diagnosis coverage expresses the number of people with new and relapsed bacteriologically confirmed pulmonary TB as a percentage of the total number people with new and relapsed notified pulmonary TB. This analysis can be used to identify what percent of people with pulmonary TB are laboratory confirmed compared to clinically diagnosed. As the use of WRDs is expanded to confirm all new pulmonary diagnoses, one should see an increase in bacteriological confirmation over time. By measuring bacteriological confirmation in people with new and previously treated TB, countries can track the rollout and use of WRDs. Additionally, the percent of people with bacteriological confirmation can be compared against national and global standards or targets as a proxy for measuring laboratory performance or capacity within a country. This is also an important indicator of drug susceptibility testing (DST) coverage and drug-resistant TB (DR-TB) detection, as both require bacteriological testing to have documented results for resistance to at least rifampicin.

As mentioned above, the expectation is not to have 100% bacteriological confirmation; there will continue to be instances of clinically diagnosed patients. However, if the percent falls below 50% in a given setting, a review of the diagnostic tests being used and the validity of clinical diagnoses would be warranted (e.g., via a clinical audit). Low reported bacteriological diagnosis coverage may be due to several contributing factors, including gaps in referral for specimen testing, weak sample transport networks, breakdown of diagnostic platforms, stockout of consumables required for testing, and weaknesses in the system for reporting results to providers. Improved supervision and training, as well as improved supply chain and specimen transport systems, can help address these issues and improve the performance of this indicator.

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Changelog

January, 2024: Updated the name, definition, and other information based on the Interim PBMEF Tuberculosis Indicator Compendium.