Table 1. Baseline characteristics of household contacts and risk factors for incident TB disease among household contacts of adult pulmonary TB patients in India.
| HHC Characteristics | Overall | iTBD | IR/1000 PY (95% CI) | Univariate IRR (95% CI) | p-value | Adjusted IRR (95% CI) (Overall model) | p-value |
|---|---|---|---|---|---|---|---|
| Denominators | 997 | 20 | |||||
| Age group (years) | 0.99 (0.96–1.03)a | 0.78 | |||||
| < 6 | 83 (8%) | 2 (10%) | 15 (2–53) | 1 | |||
| 6–12 | 144 (14%) | 4 (20%) | 17 (5–44) | 1.17 (0.21–6.37) | 0.86 | ||
| 13–17 | 94 (9%) | 0 | 0 | NA | NA | ||
| 18–44 | 500 (50%) | 11 (55%) | 14 (7–24) | 0.92 (0.20–4.17) | 0.92 | ||
| ≥45 | 176 (18%) | 3 (15%) | 10 (2–30) | 0.70 (0.12–4.21) | 0.7 | ||
| Gender | |||||||
| Male | 442 (44%) | 10 (50%) | 14 (7–25) | 1.20 (0.50–2.88) | 0.69 | 0.86 (0.25–2.91) | 0.80 |
| Female | 555 (56%) | 10 (50%) | 11 (5–21) | 1 | 1 | ||
| Marital status | Not included | ||||||
| Never married | 189 (26%) | 5 (36%) | 16 (5–38) | 1 | |||
| Married | 498 (69%) | 9 (64%) | 11 (5–21) | 0.69 (0.23–2.07) | 0.51 | ||
| Divorced/ Widowed | 34 (5%) | 0 | 0 | NA | |||
| Level of education | Not included | ||||||
| ≤ Primary | 351 (37%) | 9 (47%) | 16 (7–30) | 1 | |||
| Highschool | 399 (42%) | 6 (32%) | 9 (3–20) | 0.58 (0.21–1.62) | 0.3 | ||
| > Junior college | 199 (21%) | 4 (21%) | 13 (3–33) | 0.80 (0.25–2.6) | 0.71 | ||
| HIV infection | |||||||
| Positive | 15 (2%) | 2 (11%) | 99 (12–359) | 3.20 (0.93–10.99) | 0.06 | 29.08 (2.38–355.77) | 0.01 |
| Negative | 937 (98%) | 17 (89%) | 111 (7–179) | 1 | 1 | ||
| Baseline DMb | Not included | ||||||
| Yes | 67 (9%) | 1 (7%) | 8 (0–47) | 0.64 (0.21–1.91) | 0.42 | ||
| No | 667 (91%) | 13 (93%) | 12 (7–21) | 1 | |||
| Incident DMb | Not included | ||||||
| Yes | 3 (0%) | 0 | 0 | NA | |||
| No | 992 (100%) | 20 (100%) | 13 (8–19) | ||||
| Smokingc | |||||||
| Current | 58 (9%) | 0 | 0 | NA | 0.46 | Not included | |
| Former | 21 (3%) | 1 (8%) | 27 (1–149) | 2.15 (0.28–16.57) | |||
| Never | 597 (88%) | 12 (92%) | 12 (6–22) | 1 | |||
| Alcohol consumptiond | Not included | ||||||
| Yes | 129 (13%) | 3 (15%) | 14 (3–41) | 1.09 (0.30–3.91) | 0.89 | ||
| No | 530 (54%) | 11 (55%) | 13 (6–23) | 1 | |||
| BCG scar | Not included | ||||||
| Present | 569 (70%) | 10 (71%) | 11 (5–20) | 1.09 (0.34–3.48) | 0.88 | ||
| Absent | 240 (30%) | 4 (29%) | 10 (3–25) | 1 | |||
| Past history of TB | Not included | ||||||
| Yes | 36 (4%) | 0 | 0 | NA | |||
| No | 959 (96%) | 20 (100%) | 13 (8–20) | ||||
| Undernourishede | |||||||
| No | 788 (81%) | 13 (70%) | 10 (5–17) | 1 | 1 | ||
| Yes | 187 (19%) | 7 (30%) | 23 (9–48) | 2.30 (0.92–5.76) | 0.08 | 6.16 (1.89–20.03) | 0.003 |
| Baseline TSTf | Not included | ||||||
| Negative | 714 (74%) | 13 (72%) | 11 (6–19) | 1 | |||
| Positive (≥10mm) | 252 (26%) | 5 (28%) | 13 (4–30) | 1.17 (0.42–3.27) | 0.77 | ||
| Baseline TSTf | Not included | ||||||
| Negative | 442 (44%) | 8 (44%) | 11 (5–22) | 1 | |||
| Positive (≥5mm) | 524 (56%) | 10 (56%) | 12 (6–22) | 1.08 (0.43–2.74) | 0.87 | ||
| Baseline IGRAg | Not included | ||||||
| Negative | 455 (48%) | 9 (47%) | 12 (6–23) | 1 | |||
| Positive | 484 (52%) | 11 (53%) | 14 (7–26) | 1.17 (0.48–2.81) | 0.73 | ||
| Baseline TSTf & IGRAg | Not included* | ||||||
| Both Negative | 246 (45%) | 5 (45%) | 14 (7–27) | 1 | |||
| Both positive (TST≥5mm) | 301 (55%) | 6 (55%) | 18 (6–42) | 1.01 (0.31–3.29) | >0.95 | ||
| Baseline TSTf &/or IGRAg | |||||||
| Both Negative | 290 (29%) | 5 (25%) | 11 (3–25) | 1 | 1 | ||
| Either Positive (TST≥5mm) | 707 (71%) | 15 (75%) | 13 (7–22) | 1.27 (0.46–3.48) | 0.65 | 1.68 (0.45–6.30) | 0.44 |
| Baseline TSTf & IGRAg | Not included* | ||||||
| Both Negative | 183 (32%) | 5 (36%) | 14 (7–27) | 1 | |||
| Both positive (TST≥10mm) | 386 (68%) | 9 (64%) | 18 (6–42) | 1.26 (0.42–3.77) | 0.67 | ||
| Baseline TSTf &/or IGRAg | Not included* | ||||||
| Both Negative | 444 (45%) | 9 (47%) | 13 (6–24) | 1 | |||
| Either Positive (TST≥10mm) | 553 (55%) | 11 (53%) | 12 (6–22) | 0.99 (0.41–2.41) | >0.95 |
HHC = Household contacts of adult patients with pulmonary TB; TBD = TB disease; SD = standard deviation
a. Age is used as linear variable in multivariable models
b. Diabetes mellitus (DM): defined as- Known case of DM or, HB A1c ≥ 6.5%, or Fasting Blood Glucose (FBG) ≥ 126 mg/dl or Random Blood glucose ≥ 200 mg/dl
c. Smoking: Never smokers defined as those HHC who smoked <100 cigarettes in their lifetime and were not current smokers; Past smokers defined as those HHC who smoked ≥ 100 cigarettes in their lifetime and were not currently smoking; and Current smokers defined as those HHC who smoked ≥100 cigarettes in their lifetime and reported current smoking
d. Alcohol: defined as history of any consumption of alcoholic drink
e. Undernourished: defined as BMI < 18.5 kg/m2 for HHC ≥ 18 years of age, BMI for age ≤ minus 2 SD for HHC >10 years and <18 years of age and weight for age ≤ minus 2 SD for HHC ≤10 years of age
f. TST- positive test defined as an induration of ≥ 5 mm or more
g. IGRA- positive test defined as ≥0.35 IU/ml.