Label | Definition |
---|---|
TB | Tuberculosis |
LTBI | Latent Tuberculosis Infection |
AcTB | Active Tuberculosis |
HTC | Household Tuberculosis Contact |
TMREL | Theoretical Minimum Risk Exposure Level |
PAF | Population Attributable Fraction |
.. todo:: Provide a brief description of the HTC risk.
Note
This section will describe the Vivarium modeling strategy for risk effects. For a description of Vivarium modeling strategy for risk exposure, see the :ref:`Household Tuberculosis Contact <2019_risk_hh_tb_contact>` page.
Outcome | Outcome type | Outcome ID | Affected measure | Note |
---|---|---|---|---|
LTBI | Cause | 954 | Incidence |
Incidence of LTBI is calculated from IHME’s Bayesian disease modeling software, DisMod-MR. More information can be found on :ref:`Latent Tuberculosis Cause Model Document <2017_cause_latent_tb>`.
We conducted a meta-analysis by reviewing over 200 papers to determine the relative risk (RR) for HTC exposure, among the under 5 and the 5+ population. The reference group was defined as indivudals without exposure to HTC. After discussion with a TB expert, we selected 11 papers for inclusion in the under 5 meta-analysis and approximately 20 papers for the 5+ meta-analysis (see References for full list of cited works). Based on the evidence, the risk model incorporates a RR of 4.72 (95%CI 3.87 to 5.76) for under 5 HTC-exposed population, and a RR of 1.75 (95%CI 1.6 to 1.91) for 5+ HTC-exposed population.
Relative risk of HTC exposure for under 5 population
Relative risk of HTC exposure for 5+ population
Relative RisksExposure Category | Relative Risk | Note |
---|---|---|
Under 5 HTC-exposed | 4.72 (95%CI 3.87 to 5.76) | Specific to individuals under age of 5 years who live in a household with AcTB case, does not vary by sex and location |
5+ HTC-exposed | 1.75 (95%CI 1.6 to 1.91) | Specific to individuals above age of 5 years who live in a household with AcTB case, does not vary by sex and location |
HTC-unexposed | 1 | TMREL |
The incidence of LTBI for individuals with exposure to HTC is:
i_{HTC-exposed} = i_{LTBI}\times (1 - PAF)\times RR_{HTC}
The incidence of LTBI for individuals without exposure to HTC is:
i_{HTC-unexposed} = i_{LTBI}\times (1 - PAF)
The PAF is derived from the relative risk and risk exposure of HTC:
PAF = \frac{p\times (RR_{HTC} - 1)}{p\times (RR_{HTC} - 1) + 1}
- Where:
- i_{LTBI} is the incidence of LTBI, calculated from DisMod-MR;
- RR_{HTC} is the age-dependent relative risk of developing LTBI for HTC-exposed versus HTC-unexposed, developed by meta-analysis;
- p is the risk exposure/probability of HTC, deveried from prevalence of AcTB and household structure data.
.. todo:: List assumptions and limitations of risk modeling strategy (confounding, mediation, modification, etc.)
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