References in the content below refer to the PBMEF Guide.
Definitions
Number of contacts of bacteriologically confirmed pulmonary tuberculosis (TB) patients who were evaluated for active TB and TB infection (TBI), out of those eligible, expressed as a percentage.
Contact investigation (CI) is a systematic process for identifying previously undiagnosed people with TB among the contacts of an index case. Contact investigation consists of identification, prioritization, and clinical evaluation. It may also include testing for TBI to identify candidates for TB preventive treatment (TPT).
Calculation: (Numerator/Denominator) x 100
Numerator
Denominator
Ref # |
CI-1
|
Tier Level |
Core Indicator
|
Category |
Reach
|
Type |
Core Outcome
|
Unit of Measure |
Percent of contacts
|
Data Type |
Percentage
|
Disaggregations |
Age
Gender
Subnational
|
Reporting Level |
National
|
Reporting Frequency |
Annually
|
This indicator is reported on national TB program (NTP) official records, such as contact registers. If these registers do not exist, data can be collected from implementing partners supporting contact investigation interventions. The denominator can also be estimated by taking the estimated average household size, assuming the index cases come from different households. See indicator CI-2 for more information.
This indicator is newly introduced in the WHO 2020 Global Data Collection Form and can be calculated using the WHO database. The variable for the numerator is newinc_con_screen and the denominator is newinc_con
Contact investigation is an important first step both for active case finding and TPT. CI identifies people recently exposed to TB with a high risk of developing TB disease or TB infection and can help reduce the spread of TB in a community. As much as 5% of the contacts of TB cases can have active TB disease. This indicator measures the ability of NTPs to systematically identify and evaluate contacts of bacteriologically confirmed pulmonary TB patients for active TB and TBI.
Contact investigations are poorly implemented in many countries and without immediate improvement will result in underachievement of the United Nations High Level Meeting targets. Contact investigation coverage is one of the top 10 indicators of the WHO End TB Strategy with a recommended target level of 90% by 2025.
Increases in CI coverage will result in greater detection of TB cases and provision of appropriate anti- TB therapy (for confirmed TB cases) or TPT (for those without TB disease). Moreover, CI is a good public health practice and essential for tracking several infectious diseases (such as COVID-19).
The total number of contacts identified can be compared to the number of contacts investigated to determine the gap in overall CI coverage. This is something that can be analyzed as a trend over time or
The total number of contacts identified can be compared to the number of contacts investigated to determine the gap in overall CI coverage. This is something that can be analyzed as a trend over time or compared between regions to better understand contact-tracing performance. Comparisons with a country’s CI coverage targets will provide the impetus to further strengthen the implementation of CI strategies within an NTP.
Another comparison could be made between the number of contacts investigated per index case. Simply charting the trend of the average number of contacts investigated per index case can also give an understanding about how effective the contact investigation is.
Data on CI coverage will also help countries monitor efforts to enroll eligible contacts on TPT. For example, CI coverage data can be viewed in conjunction with the number of active TB cases detected among the contacts (contact yield) and the number of eligible contacts put on TPT for TBI. Data can also be collected at the subnational level and used to learn from the geographic distribution of contacts. Data should be reported annually at a minimum but semiannually or quarterly reporting will improve the timeliness of data for decision making. See Appendix 2 for a more detailed pathway and cascade for contact investigations.