Table 2. Baseline characteristics of pulmonary TB index patients and risk factors for incident TB disease among household contacts of adult pulmonary TB patients in India.
| Index Case 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) | |||||||
| 18–44 | 633 (63%) | 12 (60%) | 12 (6–21) | 1 | 1 | ||
| ≥45 | 364 (37%) | 8 (40%) | 13 (6–26) | 1.07 (0.44–2.61) | 0.88 | 2.63 (0.80–8.64) | 0.11 |
| Gender | |||||||
| Male | 611 (61%) | 11 (55%) | 11 (6–20) | 0.77 (0.32–1.86) | 0.56 | 2.50 (0.63–9.84) | 0.19 |
| Female | 386 (39%) | 9 (45%) | 15 (7–28) | 1 | 1 | ||
| HIV infection | |||||||
| Positive | 66 (7%) | 3 (16%) | 34 (7–100) | 3.20 (0.93–10.99) | 0.06 | 0.47 (0.04–5.19) | 0.53 |
| Negative | 923 (93%) | 16 (84%) | 11 (6–17) | 1 | 1 | ||
| Baseline Diabetes Mellitusa | Not included | ||||||
| Yes | 259 (26%) | 4 (20%) | 9 (2–23) | 0.64 (0.21–1.91) | 0.42 | ||
| No | 733 (74%) | 16 (80%) | 14 (8–23) | 1 | |||
| Smokingb | Not included | ||||||
| Current | 127 (13%) | 3 (15%) | 15 (3–45) | 1.04 (0.30–3.56) | 0.95 | ||
| Former | 184 (18%) | 1 (5%) | 3 (0–18) | 0.22 (0.03–1.63) | 0.14 | ||
| Non-Smoker | 684 (69%) | 16 (80%) | 15 (8–24) | 1 | |||
| Alcohol consumptionc | Not included | ||||||
| Yes | 430 (44%) | 6 (30%) | 8 (3–18) | 0.53 (0.20–1.38) | 0.2 | ||
| No | 555 (56%) | 14 (70%) | 16 (9–27) | 1 | |||
| Microbiologically confirmed TBd | Not included | ||||||
| Yes | 895 (92%) | 18 (90%) | 12 (7–20) | 0.70 (0.16–3.01) | 0.63 | ||
| No | 83 (8%) | 2 (10%) | 18 (2–64) | 1 | |||
| Xpert MTB/Rif | Not included | ||||||
| Positive | 709 (85%) | 14 (78%) | 12 (7–21) | 0.54 (0.18–1.63) | 0.27 | ||
| Negative | 124 (15%) | 4 (22%) | 23 (6–59) | 1 | |||
| Smeare/Culturef (Baseline) | |||||||
| Culture+/Smear- | 135 (15%) | 1 (5%) | 5 (1–29) | 0.46 (0.04–5.02) | 0.52 | NA | |
| Culture-/Smear+ | 12 (1%) | 1 (5%) | 46 (1–257) | 3.98 (0.36–43.87) | 0.26 | 11.50 (0.71–186.51) | 0.09 |
| Culture+/Smear+ | 664 (72%) | 16 (80%) | 15 (8–24) | 1.26 (0.29–5.50) | 0.75 | 1.34 (0.20–8.87) | 0.76 |
| Culture-/Smear- | 113 (12%) | 2 (10%) | 12 (1–42) | 1 | 1 | ||
| Smeare/Culturef (Month 1) | Not included | ||||||
| Culture+/Smear- | 244 (28%) | 4 (21%) | 10 (3–26) | 0.52 (0.17–1.65) | 0.26 | ||
| Culture-/Smear+ | 44 (5%) | 0 | 0 | NA | NA | ||
| Culture+/Smear+ | 184 (21%) | 3 (16%) | 9 (2–27) | 0.48 (0.14–1.71) | 0.26 | ||
| Culture-/Smear- | 401 (46%) | 12 (63%) | 19 (1–34) | 1 | |||
| Smeare/Culturef (Month 2) | Not included | ||||||
| Culture+/Smear- | 109 (13%) | 4 (25%) | 22 (6–57) | 1.87 (0.60–5.79) | 0.28 | ||
| Culture-/Smear+ | 53 (6%) | 0 | 0 | NA | NA | ||
| Culture+/Smear+ | 55 (7%) | 0 | 0 | NA | NA | ||
| Culture-/Smear- | 604 (74%) | 12 (75%) | 12 (6–21) | 1 | |||
| AFB (Baseline) | Not included | ||||||
| Negative | 418 (42%) | 8 (40%) | 13 (5–25) | 1 | |||
| Positive | 572 (58%) | 12 (60%) | 13 (6–22) | 0.99 (0.41–2.43) | >0.95 | ||
| LJ Colony count (Baseline) (CFU/HPF) | Not included | ||||||
| Negative | 214 (22%) | 7 (37%) | 21 (8–43) | 1 | |||
| < 10 | 99 (10%) | 2 (11%) | 12 (2–45) | 0.60 (0.12–2.87) | 0.52 | ||
| 10–100 | 350 (36%) | 4 (21%) | 8 (2–20) | 0.37 (0.11–1.27) | 0.12 | ||
| > 100 | 306 (32%) | 6 (32%) | 11 (4–24) | 0.52 (0.18–1.55) | 0.24 | ||
| Index cavitory disease | Not included | ||||||
| No | 382 (43%) | 7 (41%) | 11 (4–23) | 1 | |||
| Yes | 507 (57%) | 10 (59%) | 12 (6–22) | 1.09 (0.41–2.85) | 0.87 |
TBD = TB disease; CFU/HPF = Colony Forming Units per High Power Field
a. 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
b. Current smoker: 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
c. Alcohol: defined as history of any consumption of alcoholic drink
d. AFB smear and/or Gene Xpert and/or TB culture positive
e. AFB Smear positive defined as scanty, 1+, 2+ or 3+ result
f. Culture positive defined as any culture (MGIT &/or LJ) positive for MTB