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. Author manuscript; available in PMC: 2016 Sep 1.
Published in final edited form as: J Acquir Immune Defic Syndr. 2015 Sep 1;70(1):83–90. doi: 10.1097/QAI.0000000000000712

Table 1.

Cohort model inputs including costs, effectiveness measures and tree probabilities

Model Parameter Inputs Parameter Value Range
(Min, Max)
Data Source
Cost Parameters
Cost of 1st Line TB Treatment $185 (154, 236) 20,21

Cost of 2nd Line TB Treatment $1759 (1353, 2351) 20,21

Lifetime cost of ART started immediately $2563 (0, 4000) CHAI Treatment costs for HIV (MATCH study) 22

Cost of a symptom screen $0.20 (0, 1) Chepetsa costing study

Cost of standard smear (1000 tests/year at peripheral lab) $4.06 (1, 10) Chepetsa costing study

Effectiveness parameters
(Including effectiveness of ART)
DALY – 1st line treatment success −1.53 (−2.53, −0.5) 14,23

DALY – 2nd line treatment success −1.9878 (−2.99, −0.99) 14,23

DALY – Death −23.8967 (−27.8967, −29.90) 9,13,14

DALY – No TB, ART initiation (delayed and immediate) −1.2710 (−2.2710, −0.27) 9,13,14

Cohort proportions
Probability of active TB among patients newly diagnosed with HIV in Malawi .024 (0.01, 0.06) Chepetsa, facility report

Probability that symptomatic patients would receive smear results without screening .40 (0,1)

Probability that CD4+ <350 at time of screening .60 (0.5, 0.75) 24
Probability that missed TB case is later diagnosed with TB outside of screening 0.66 (0.61, 0.71) 8
Probability of loss to follow up during TB treatment .15 (0.1, 0.21) 23

Probability of Rifampicin resistance among patients with TB .004 (0.0014, 0.01) 8

Probability of death among TB patients with HIV given treatment failure, missed diagnosis, or loss to follow-up 1 (0.63, 1) Assumption 25

Probability of treatment success, MDR-TB treated with 1st line drugs .47 (0.42, 0.52) 10

Probability of Treatment success, smear-negative TB treated with 1st line therapy .8 (0.72, 0.88) 8

Probability of Treatment success, smear positive TB treated with 1st line therapy .87 (0.78, 0.96) 8

Probability of treatment success, 2nd line .80 (0.7, 0.9) 11

Diagnostic Parameters
Sensitivity of Xpert for RIF resistance .976 (0.94, 0.99) 26,27

Sensitivity of Xpert for LED-negative TB .718 (0.29, 0.79) 26–28

Sensitivity of Xpert for LED-positive TB .977 (0.92, 0.99) 26,27

Sensitivity of LED for TB among Smear negatives 0.095 (0.09, 0.2) 8,25,29

Sensitivity of LED for TB among Smear positives 1 (0, 1) 29

Specificity of GXP .992 (0.98, 0.996) 26,27

Specificity of GXP for RIF resistance 1 (0.9, 1) 26,27

Specificity of LED 0.944 (0.92, 0.96) 30

Sensitivity of standard smear among LED positive people with HIV .37 (0.36, 0.7) 8,25

Specificity of smear among people with HIV .8 (0, 1)

Abbreviations: TB: active tuberculosis disease, GXP: Gene Xpert, LED: light emitting diode fluorescence microscopy, MDR: multi drug resistant tuberculosis, ART: antiretroviral therap