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Table 2 Distribution of age, gender and risk factors for tuberculosis (TB) in 525 household contacts of 176 adults with confirmed pulmonary TB according to infection categories at baseline Contact Investigation

From: Identification of subclinical tuberculosis in household contacts using exposure scores and contact investigations

  Missing Total with available data N = 525 TST−/QFT-1 N = 167 TST+ or QFT + 1 N = 167 TST+/QFT + 1 N = 113 Subclinical TB2 at baseline N = 29
n (%) n (%) n (%) n (%) n (%) n (%)
Interview
 Gender (male) 49 (9.3) 193 (40.5) 79 (47.3) 61 (36.5) 39 (34.5) 14 (48.3)
 Age (years)3 50 (9.5)      
  < 5   38 (8.0) 22 (13.2) 8 (4.8) 6 (5.4) 2 (6.9)
 5–14   138 (29.1) 41 (24.6) 47 (28.1) 38 (33.9) 12 (41.4)
  > 14   299 (62.9) 104 (62.3) 112 (67.1) 68 (60.7) 15 (51.7)
Individual risk factors
 Diabetes mellitus 49 (9.3) 9 (1.9) 2 (1.2) 5 (3.0) 1 (0.9) 1 (3.4)
 Smoking 49 (9.3) 118 (24.8) 35 (21.0) 48 (28.7) 27 (23.9) 8 (27.6)
Tuberculosis Contact Score
 Mean (St.dev)   10.9 (2.3) 10.4 (2.3) 11.1 (2.3) 11.6 (2.0) 11.2 (1.8)
 Symptoms4   13 (2.7) 5 (3.0) 4 (2.4) 3 (2.7) 1 (3.4)
Environmental risk factors
 Crowding5 (mean, St.dev) 55 (10.5) 4.25 (2.04) 4.41 (2.25) 4.14 (1.98) 4.18 (1.89) 3.43 (1.53)
In-door pollution6 55 (10.5)      
 LPG   60 (11.4) 14 (9.8) 21 (14.2) 17 (16.3) 2 (7.4)
 Kerosene   15 (2.9) 3 (2.1) 4 (2.7) 5 (4.8) 1 (3.7)
 Wood + agri residue   329 (75.2) 126 (88.1) 123 (83.1) 82 (78.8) 24 (88.9)
Examination and tests
 Tuberculin Skin Test (TST) 49 (9.3)   
 mm (median, range)   8.0 (34) 6.0 (9) 7.0 (34) 14.0 (23) 7.0 (12)
  ≥ 10 mm   152 (31.9) 0 30 (18.0) 113 (100) 9 (31.0)
 Quantiferon (QFT) 51 (9.7)   
 IU/mL (median, range)   0.56 (19.8) 0.03 (3.2) 1.44 (10.7) 4.58 (9.6) 1.36 (10.1)
  ≥ 0.35 IU/mL   266 (56.1) 0 137 (82.0) 113 (100) 16 (59.3)
Mtb specimen for culture 32 (6.1)   
 2 of 2 samples harvested   471 (98.9) 162 (97.9) 167 (100) 113 (100) 29 (100)
 1 of 2 samples harvested   5 (1.1) 5 (3.0) 0 0 0
 Smear +   7 (1.5) 2 (1.2) 2 (1.2) 2 (1.8) 1 (3.4)
 Chest X-ray 49 (9.3)   
 Abnormal, not TB   13 (2.7) 4 (2.4) 1 (0.6) 7 (6.2) 1 (3.4)
 Abnormal, TB   15 (3.2) 3 (1.8) 7 (4.2) 3 (2.7) 2 (6.9)
 BCG scar present 96 (18.3)   
 Yes   221 (51.5) 85 (55.6) 76 (50.7) 46 (46.0) 14 (53.8)
BMI and BMIZ7
 BMI when aged ≥15 years. Mean (st.dev) 29 (8.8) 19.6 (3.19) 19.30 (3.03) 20.15 (3.72) 19.25 (2.61) 18.69 (2.13)
 BMIZ when aged< 15 years. Mean (st.dev) 9 of 187 −0.14 (1.70) − 0.48 (1.85) 0.19 (1.33) −0.14 (1.91) − 0.15 (1.71)
  1. 1Tuberculin Skin Test (TST) was dichotomized around the cutoff 10 mm; ≥10 mm corresponding to TST+ and < 10 mm corresponding to TST-. Quantiferon (QFT) was dichotomized around the cutoff 0.35 IU/mL; ≥0.35 IU/mL corresponding to QFT+ and < 0.35 IU/mL corresponding to QFT-. Analysis limited to subjects with both test results. 2Subjects with growth of Mycobacterium tuberculosis (Mtb) in liquid culture of respiratory specimen. 3WHO based age categories.4 ≥ 1 of the following: cough > 2 wks, fever/night sweats, loss of weight/appetite, haemoptysis, chestpain. 5Number of household members divided on rooms in the house. 6By type of fuel: LPG, Kerosene, Wood + agricultural residue. 7Body Mass Index (BMI), Body Mass Index Z-score (BMIZ)