References in the content below refer to the PBMEF Guide.
Definitions
Percent of new and relapse bacteriologically confirmed pulmonary tuberculosis (TB) cases (smear positive or culture positive or positive by World Health Organization [WHO]-recommended rapid diagnostics test, such as Xpert MTB/RIF) among notified new and relapse pulmonary TB cases during the reporting period.
Calculation: (Numerator/Denominator) x 100
Numerator
Denominator
Ref # |
DT-12
|
Tier Level |
Core Indicator
|
Category |
Reach
|
Type |
Core Outcome
|
Unit of Measure |
Percent of cases
|
Data Type |
Percentage
|
Disaggregations |
Age
Gender
Subnational
|
Reporting Level |
National
|
Reporting Frequency |
Annually
|
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 incidence— notification gaps—the proportion of notified cases that are bacteriologically confirmed needs to be monitored to ensure that people are correctly diagnosed and started on the most effective treatment regimen as early as possible. This indicator measures a program’s capacity to detect TB accurately and rapidly using new diagnostics and to increase the percentage of cases confirmed bacteriologically by scaling up the use of recommended diagnostics that are more sensitive than smear microscopy.
Globally, in 2019, 57% of pulmonary cases were bacteriologically confirmed, a slight increase from 55% in 2018 and 56% in 2017. The End TB Strategy has set a target of 90% of new cases and 95% of relapse cases for bacteriological diagnosis coverage 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 shows the number of new and relapsed bacteriologically confirmed pulmonary TB cases compared to the total number of new and relapsed notified pulmonary TB cases. This analysis sheds light on what proportion of pulmonary TB cases are laboratory confirmed compared to clinically confirmed. As the use of GeneXpert is expanded to test all new pulmonary cases, one should see an increase in bacteriological confirmation of these cases over time.
By measuring bacteriological confirmation in new and previously treated cases, countries can track the rollout and use of GeneXpert and other molecular WHO-recommended rapid diagnostic (WRD). Additionally, the proportion of bacteriologically confirmed cases 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. See Appendix 2 for examples of this indicator in DS and DR-TB treatment pathways and cascades.
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 proportion 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 over-reliance on clinical diagnosis by the healthcare providers, insufficient effort to request patients to submit specimens for testing, the laboratory not receiving or processing the specimen, or results not being returned to the clinic or recorded in clinical files. Improved supervision and training, as well as improved supply chain, can help address these issues and improve the accuracy and reliability of this indicator.