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Table 5 Factors associated with QFT conversion at visit 2 and visit 3 using different definitions of conversion

From: Interpretation of serial interferon-gamma test results to measure new tuberculosis infection among household contacts in Zambia and South Africa

 

Definition 1

(< 0.35, increase 0.35)

Definition 2

(< 0.2, ≥0.7)

Definition 3

(< 0.2, ≥1.05)

Definition 4

(< 0.2, ≥1.4)

Unadjusted RR (95%CI)

Adjusted RR (95%CI)a

Unadjusted RR (95%CI)

Adjusted RR (95%CI)a

Unadjusted HR (95%CI)

Adjusted RR (95%CI)a

Unadjusted RR (95%CI)

Adjusted RR (95%CI)a

Both countries

 End follow-up V1-V2

1

1

1

1

1

1

1

1

 End follow-up V2-V3

0.9 (0.7–1.3)

1.0 (0.8–1.4)

0.9 (0.7–1.4)

0.9 (0.7–1.4)

1.0 (0.7–1.6)

1.0 (0.7–1.6)

1.1 (0.7–1.7)

1.1 (0.7–1.8)

Sex

 Male

1

1

1

1

1

1

1

1

 Female

0.7 (0.5–0.9)

0.7 (0.5–0.9)

0.7 (0.5–0.9)

0.7 (0.5–1.0)

0.8 (0.5–1.2)

0.8 (0.5–1.2)

0.8 (0.5–1.3)

0.8 (0.5–1.3)

Age

 15–24

1

1

1

1

1

1

1

1

 25–29

0.6 (0.4–0.9)

0.7 (0.4–1.2)

0.6 (0.3–1.1)

0.6 (0.3–1.3)

0.4 (0.2–0.9)

0.5 (0.2–1.1)

0.4 (0.2–0.9)

0.3 (0.1–0.9)

 30–34

0.6 (0.4–1.1)

0.7 (0.4–1.3)

0.6 (0.3–1.1)

0.6 (0.3–1.2)

0.7 (0.3–1.4)

0.7 (0.3–1.5)

0.6 (0.3–1.3)

0.6 (0.3–1.4)

 35–39

0.7 (0.3–1.3)

0.9 (0.5–1.6)

0.6 (0.3–1.2)

0.7 (0.3–1.5)

0.7 (0.3–1.5)

0.8 (0.4–1.8)

0.7 (0.3–1.6)

0.8 (0.3–1.8)

 40–49

0.9 (0.5–1.4)

1.0 (0.6–1.6)

0.7 (0.3–1.2)

0.7 (0.4–1.4)

0.5 (0.2–1.2)

0.6 (0.3–1.3)

0.3 (0.1–0.9)

0.3 (0.1–1.0)

 50+

1.2 (0.8–1.8)

1.3 (0.8–2.0)

0.9 (0.5–1.7)

1.1 (0.6–1.9)

0.9 (0.5–1.7)

0.9 (0.5–1.9)

0.9 (0.5–1.8)

1.0 (0.5–2.1)

HIV status b

 HIV negative

1

1

1

1

1

1

1

1

 HIV positive, no ARV

0.6 (0.4–0.8)

0.7 (0.4–0.9)

0.7 (0.4–0.9)

0.8 (0.5–1.3)

0.7 (0.4–1.0)

0.8 (0.5–1.4)

0.7 (0.4–1.2)

0.9 (0.6–1.9)

 HIV positive & ARV

0.7 (0.3–1.6)

0.7 (0.3–1.6)

0.9 (0.4–2.2)

1.0 (0.4–2.4)

1.2 (0.5–2.7)

1.2 (0.5–2.8)

0.8 (0.3–2.6)

0.8 (0.3–2.6)

Region by TST prevalence

 Zambia, Lusaka, high TST

1

1

1

1

1

1

1

1

 Zambia, Urban, high TST

0.8 (0.5–1.2)

0.7 (0.4–1.0)

0.9 (0.5–1.5)

0.7 (0.4–1.2)

0.8 (0.4–1.3)

0.7 (0.4–1.2)

0.8 (0.4–1.4)

0.6 (0.3–1.1)

 Zambia, Urban, low TST

0.5 (0.3–0.8)

0.5 (0.3–0.7)

0.6 (0.3–1.0)

0.5 (0.3–0.9)

0.5 (0.3–1.0)

0.5 (0.3–1.0)

0.5 (0.3–0.9)

0.4 (0.2–0.8)

 Zambia, Rural, low TST

0.7 (0.4–1.3)

0.5 (0.3–1.0)

0.7 (0.3–1.5)

0.5 (0.2–1.2)

0.8 (0.4–1.9)

0.7 (0.3–1.6)

0.9 (0.4–1.9)

0.6 (0.3–1.5)

 South Africa, high TST

0.8 (0.5–1.2)

0.7 (0.5–1.1)

0.8 (0.4–1.4)

0.7 (0.4–1.3)

0.7 (0.3–1.3)

0.6 (0.3–1.3)

0.6 (0.3–1.2)

0.5 (0.2–1.1)

 South Africa, low TST

0.4 (0.2–0.7)

0.4 (0.2–0.6)

0.5 (0.3–1.1)

0.5 (0.3–1.0)

0.5 (0.3–1.1)

0.5 (0.2–1.2)

0.4 (0.2–0.9)

0.4 (0.2–0.9)

Zambia

 End follow-up V1-V2

1

1

1

1

1

1

1

1

 End follow-up V2-V3

0.9 (0.7–1.4)

1.1 (0.8–1.5)

0.9 (0.6–1.4)

1.0 (0.7–1.6)

1.1 (0.7–1.8)

1.2 (0.8–1.9)

1.1 (0.7–1.8)

1.2 (0.7–1.9)

Sex

 Male

1

1

1

1

1

1

1

1

 Female

0.7 (0.5–0.9)

0.7 (0.5–1.0)

0.7 (0.5–1.1)

0.7 (0.5–1.1)

0.8 (0.5–1.3)

0.8 (0.5–1.4)

0.9 (0.5–1.5)

0.9 (0.5–1.6)

Age

 15–24

1

1

1

1

1

1

1

1

 25–29

0.6 (0.3–1.0)

0.7 (0.4–1.3)

0.6 (0.3–1.2)

0.7 (0.3–1.6)

0.4 (0.2–1.1)

0.5 (0.2–1.4)

0.4 (0.1–1.0)

0.4 (0.1–1.3)

 30–34

0.6 (0.3–1.2)

0.7 (0.4–1.4)

0.6 (0.3–1.3)

0.7 (0.3–1.5)

0.7 (0.3–1.6)

0.8 (0.4–1.8)

0.6 (0.2–1.4)

0.6 (0.3–1.5)

 35–39

0.6 (0.3–1.4)

0.8 (0.4–1.8)

0.6 (0.2–1.6)

0.8 (0.3–1.9)

0.7 (0.3–1.8)

0.9 (0.3–2.3)

0.6 (0.2–1.7)

0.7 (0.3–2.2)

 40–49

0.8 (0.5–1.4)

1.0 (0.5–1.7)

0.7 (0.3–1.4)

0.8 (0.4–1.8)

0.4 (0.2–1.2)

0.5 (0.2–1.4)

0.4 (0.1–1.1)

0.4 (0.1–1.3)

 50+

1.3 (0.8–2.2)

1.5 (0.9–2.5)

1.2 (0.6–2.3)

1.4 (0.7–2.7)

1.1 (0.6–2.3)

1.2 (0.6–2.6)

1.2 (0.6–2.3)

1.3 (0.6–2.7)

HIV status

 HIV negative

1

1

1

1

1

1

1

1

 HIV positive, no ARV

0.5 (0.4–0.8)

0.6 (0.4–1.0)

0.5 (0.3–0.8)

0.6 (0.3–1.1)

0.5 (0.3–0.9)

0.6 (0.3–1.2)

0.5 (0.3–0.9)

0.7 (0.4–1.4)

 HIV positive & ARV

0.7 (0.3–1.5)

0.7 (0.3–1.7)

1.2 (0.5–2.7)

1.1 (0.5–2.8)

1.4 (0.6–3.1)

1.4 (0.6–3.4)

0.9 (0.3–2.8)

0.9 (0.3–3.0)

Region by TST prevalence

 Lusaka, high TST

1

1

1

1

1

1

1

1

VUrban, high TST

0.8 (0.5–1.2)

0.6 (0.4–0.9)

0.9 (0.5–1.5)

0.6 (0.4–1.1)

0.8 (0.4–1.3)

0.6 (0.3–1.1)

0.8 (0.4–1.4)

0.6 (0.3–1.2)

 Urban, low TST

0.5 (0.3–0.8)

0.4 (0.3–0.7)

0.6 (0.3–1.0)

0.5 (0.3–0.9)

0.5 (0.3–1.0)

0.5 (0.2–0.9)

0.5 (0.3–0.9)

0.4 (0.2–0.9)

 Rural, low TST

0.7 (0.4–1.3)

0.5 (0.2–0.9)

0.7 (0.3–1.5)

0.5 (0.2–1.1)

0.8 (0.4–1.9)

0.6 (0.3–1.4)

0.9 (0.4–1.9)

0.6 (0.2–1.4)

South Africa

 End follow-up V1-V2

1

1

1

1

1

1

1

1

 End follow-up V2-V3

0.8 (0.4–1.6)

0.8 (0.4–1.7)

0.7 (0.3–1.9)

0.8 (0.3–2.1)

0.5 (0.2–1.7)

0.6 (0.2–2.0)

0.7 (0.2–2.5)

0.9 (0.2–3.4)

Sex

 Male

1

1

1

1

1

1

1

1

 Female

0.8 (0.4–1.6)

0.7 (0.4–1.5)

0.6 (0.3–1.5)

0.6 (0.2–1.4)

0.7 (0.3–1.7)

0.6 (0.2–1.7)

0.6 (0.2–1.7)

0.4 (0.1–1.3)

Age

 15–24

1

1

1

1

1

1

1

1

 25–29

0.7 (0.3–1.8)

0.7 (0.3–2.2)

0.7 (0.2–1.9)

0.4 (0.1–1.7)

0.4 (0.1–1.9)

0.3 (0.1–1.6)

0.3 (0.03–2.3)

0.1 (0.01–1.7)

 30–34

0.7 (0.2–2.6)

0.6 (0.1–2.7)

0.4 (0.1–2.2)

0.3 (0.1–1.8)

0.6 (0.1–2.9)

0.4 (0.1–2.5)

0.7 (0.1–3.9)

0.4 (0.1–2.7)

 35–39

0.9 (0.3–2.5)

1.0 (0.4–2.9)

0.5 (0.1–2.4)

0.5 (0.1–2.1)

0.7 (0.1–3.2)

0.6 (0.1–2.8)

0.9 (0.2–4.3)

0.6 (0.2–2.7)

 40–49

1.0 (0.4–2.4)

1.1 (0.4–2.8)

0.6 (0.2–2.1)

0.5 (0.1–2.1)

0.8 (0.2–2.9)

0.6 (0.1–2.9)

0.3 (0.04–2.6)

0.2 (0.01–2.2)

 50+

0.9 (0.3–2.4)

0.9 (0.4–2.5)

0.4 (0.1–1.8)

0.3 (0.1–1.7)

0.3 (0.03–2.1)

0.2 (0.02–1.9)

0.3 (0.04–2.7)

0.2 (0.2–1.9)

HIV status b

 HIV negative

1

1

1

1

1

1

1

1

 HIV positive, no ARV

0.7 (0.4–1.5)

0.8 (0.4–1.8)

1.3 (0.6–2.9)

1.7 (0.7–4.6)

1.4 (0.6–3.4)

1.9 (0.7–5.5)

1.8 (0.6–5.0)

3.3 (0.9–12.2)

 HIV positive & ARV

0.9 (0.1–6.5)

1.1 (0.1–8.6)

N.A.

N.A.

N.A.

N.A.

N.A.

N.A.

TST prevalence

 High

1

1

1

1

1

1

1

1

 Low

0.5 (0.3–0.9)

0.5 (0.3–0.9)

0.7 (0.3–1.5)

0.8 (0.3–1.6)

0.8 (0.4–1.9)

0.9 (0.4–2.2)

0.7 (0.3–1.9)

0.9 (0.3–2.6)

  1. aNo rules were applied: time band, sex, age, HIV status, HH intervention (yes/no), and region by TST prevalence were simultaneously added to the regression models
  2. bHIV status unknown not shown
  3. Footnote: Contacts with visit 2 unknown and conversion at visit 3 were randomly assigned to have end point follow-up between visit 1-visit 2 or visit 2-visit 3. Table A4 (additional file) shows that this includes n = 27 household contacts if conversion definition 2 is used. Number of contacts who were randomly allocated for the other definitions: n = 41 definition 1; n = 21 definition 3; n = 19 definition 4 **HIV status unknown not shown
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