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Table 1 Decision analysis model parameters related to the natural history, epidemiology, and treatment of LTBI and TB

From: The potential impact and cost-effectiveness of tobacco reduction strategies for tuberculosis prevention in Canadian Inuit communities

Estimates

Reference

Probabilities

Probability (%)*

 

 •Probability of diagnosing LTBI

25

Assumption

 •Probability of completing LTBI treatment among those who start it

70.8

[69]

 •Probability of reactivation of longstanding LTBI to TB disease (non-smokers)

0.05/year

[70,71,72]

 •Probability of rapid progression following TB infection (non-smokers)**

4.5/year for 2 years

Dynamic model#

 •Probability of diagnosing active disease

90

Assumption

 •Probability of spontaneous resolution of untreated TB disease

25

[16]

 •Probability of relapse following spontaneously resolved TB

2.5

[16, 73]

 •Probability of dying from untreated TB

19/year

[74, 75]

 •Probability of relapse after treated TB disease in first year

1.5

[76]

 •Protective immunity from previous TB disease

55

Dynamic model#

QALYs for LTBI and active TB

Value (range)

 

 •Utility score for individual with active disease (treated)

0.85 (0.70–0.90)

[40]

 •Utility score for individual with active disease (untreated)

0.68 (0.65–0.72)

[39]

 •Utility score for individual with latent infection, during treatment

0.97 (0.95–1.00)

[40]

 •Utility score for individual with latent infection (untreated)

1

Assumption†

  1. INH isoniazid, LTBI latent tuberculosis infection, QALYs quality-adjusted life-years
  2. *Probabilities are one-time percentages, unless stated otherwise
  3. **After 2 years, risk of developing active TB falls to 0.05% annually
  4. †Persons with LTBI are asymptomatic
  5. #Calibrated in dynamic model