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Table 1 Input data

From: Modelling the impact of chest X-ray and alternative triage approaches prior to seeking a tuberculosis diagnosis

Parameter Value (95% CI) Source
Mean number of presumptive TB cases per day 44 (34,55) Data collated from primary health care facilities in Porto Alegre for the PROVE-IT trial [11]
TB prevalence amongst presumptive-TB cases 15.8% (14.6, 17.0%)
HIV prevalence in TB cases 44.8% (40.4, 49.2%)
HIV prevalence in no TB cases 27.3% (25.8, 28.8%)
Sensitivity - Smear microscopy for HIV-positive 45% (38, 52%) Boehme et al [35]
Specificity - Smear microscopy for HIV-positive 100% (99, 100%)
Sensitivity - Smear microscopy for HIV-negative 72% (69, 75%)
Specificity - Smear microscopy for HIV-negative 99% (99, 100%)
Sensitivity - Xpert for HIV-positive 82% (77, 87%)
Specificity - Xpert for HIV-positive 99% (98, 100%)
Sensitivity - Xpert for HIV-negative 92% (90, 94%)
Specificity - Xpert for HIV-negative 99% (98, 99%)
Sensitivity - Clinical judgement for HIV-positive 49% Estimated from reported TB case volumes in Porto Alegre and assumed sensitivity/specificity of Smear microscopy
Specificity - Clinical judgement for HIV-positive 90%
Sensitivity - Clinical judgement for HIV-negative 77%
Specificity - Clinical judgement for HIV-negative 90%
Sensitivity of X-ray for abnormalities suggestive of active TB 87% (79, 95%) WHO [26]
Specificity of X-ray for abnormalities suggestive of active TB 89% (87, 92%)
Estimated unit cost per test – Microscopy US$7.20 Estimates provided by TB research staff working with the TB program in Porto Alegre
Estimated unit cost per test – Xpert US$ 17.80
Estimated unit cost per test – X-ray US$ 6.00
Estimated % of presumptive-TB cases LTFU 10.0%
Estimated cost to treat TB case in Brazil US$840 Laurence et al [36]
Estimated cost to treat MDR-TB in Brazil US$6313