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Table 2 Prevalence of active and subclinical TB, and estimated incidence of future progression from latent or subclinical to active TB, in primary data from patient cohorts in South Africa and Pakistan used to generate parameter inputs to the TPT model

From: Isoniazid or rifampicin preventive therapy with and without screening for subclinical TB: a modeling analysis

 

People newly diagnosed with HIV, Kwa-Zulu Natal, South Africa

Household contacts, Pakistan

CD4 < 100

CD4 100–200

CD4 200–350

CD4 > 350

Age < 5 years

Age 5–14 years

Age ≥ 15 years

Total evaluated

379

442

785

1392

2194

4261

6648

Symptomatic TB at baseline, N (%)

93 (24.5%)

56 (12.7%)

42 (5.4%)

43 (3.1%)

42 (1.9%)

86 (2%)

28 (0.4%)

Subclinical TB diagnosed at baseline, N (%)

    

19 (0.9%)

58 (1.4%)

29 (0.4%)

Subclinical TB progressed to active within 3 months

16 (4.2%)

17 (3.8%)

28 (3.6%)

44 (3.2%)

   

Followed to 6 months

359

406

740

1312

NA

NA

NA

TB diagnoses, 3 to 6 months, N (%

2 (0.6%)

4 (1%)

2 (0.3%)

0 (0%)

   

Followed to 12 months

314

348

625

1096

NA

NA

NA

TB diagnoses, 6 to 12 months, N (%

7 (2.2%)

7 (2%)

5 (0.8%)

7 (0.6%)

   

Estimated lifetime incidence (95%CI) of progression of latent infections present at enrollmenta

4.7% (2.7–6.8%)

4.9% (2.9–7.1%)

3.0% (1.7–4.2%)

2.5% (2.5–3.4%)

0.6% (0.3–1.0%)

3.7% (2.3–5.3%)

1.2% (0.8–1.8%)

Estimated subclinical prevalent cases per future latent progression

    

1.4

0.4

0.4

Estimated subclinical progressors per latent progressor (95%CI)b

0.9 (0.6–1.4)

0.8 (1.5–1.2)

1.2 (0.8–1.9)

1.2 (0.9–1.9)

0.7 (0.4–1.2)

0.2 (0.1–0.3)

0.2 (0.1–0.3)

  1. aEstimates are derived by combining baseline and 12-month cohort outcomes with external data on the timing of TB progression and the balance of prevalence and incident TB in untreated household cohorts, as described in the Methods and Additional file 1
  2. bFor the household contact cohort, estimates account for the possibility that some subclinical TB will resolve without treatment rather than progressing to active TB. Uncertainty in the probability of spontaneous resolution is incorporated into the uncertainty in this parameter (Additional file 1: Table S2)