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Table 2 Bivariate analyses of factors associated with QFT positivity among study participants (n = 242)

From: Prevalence of latent tuberculosis infection among coal workers’ pneumoconiosis patients in China: a cross-sectional study

Factors QFT test Prevalence ratio (95% CI) p-value
Negative Positive
80(33.1%) 162(66.9%)
Socio-demographic characteristics
 Age (years)
   < 60 9(45.0%) 11(55.0%) 1
  60- 43(34.4%) 82(65.6%) 1.19(0.79–1.81) 0.407
   ≥ 70 28(28.9%) 69(71.1%) 1.29(0.85–1.96) 0.226
 BMI (kg/m2) a
  18.5- 35(36.1%) 62(63.9%) 1
  ≥ 25 44(30.6%) 100(69.4%) 1.09(0.90–1.31) 0.379
 Highest education level
  Primary school or lower 43(35.5%) 78(64.5%) 1
  Middle school 28(29.5%) 67(70.5%) 1.09(0.91–1.32) 0.342
  High school 9(39.1%) 17(73.9%) 1.01(0.74–1.38) 0.928
 Marital status
  Married 73(32.0%) 155(68.0%) 1
  Divorced or Widowed 7(50.0%) 7(50.0%) 0.73(0.43–1.25) 0.257
 Personal income per month (RMB)
   < 3000 7(24.1%) 22(75.9%) 1
  3000- 60(34.1%) 116(65.9%) 0.87(0.69–1.09) 0.233
   ≥ 4000 13(35.1%) 24(64.9%) 0.86(0.62–1.17) 0.323
 Family income per head per month (RMB) a
   < 6000 45(33.3%) 90(66.7%) 1
  6000- 16(32.7%) 33(67.3%) 1.01(0.80–1.27) 0.931
   ≥ 10,000 5(27.8%) 13(72.2%) 1.08(0.79–1.48) 0.613
 Place of birth
  City 7(30.4%) 16(69.6%) 1
  Countryside 73(33.3%) 146(66.7%) 0.96(0.72–1.28) 0.771
Occupational factors
 Stages of CWP
  I 62(31.3%) 136(68.7%) 1.00
  II 16(39.0%) 25(61.0%) 0.89(0.68–1.15) 0.374
  III 2(66.7%) 1(33.3%) 0.48(0.10–2.41) 0.377
 Job category
  Transport and helping 9(60.0%) 6(40.0%) 1.00
  Mining 31(36.5%) 54(63.5%) 1.59(0.84–3.01) 0.157
  Tunneling 16(25.4%) 47(74.6%) 1.87(0.10–3.52) 0.055
  Both tunneling and mining 24(30.4%) 55(69.6%) 1.74(0.92–3.29) 0.088
 Years of work
  10- 4(40%) 6(60.0%) 1.00
  20- 21(27.6%) 55(72.4%) 1.21(0.71–2.04) 0.484
  30- 47(33.3%) 94(66.7%) 1.11(0.66–1.87) 0.691
  40- 8(53.3%) 7(46.7%) 0.78(0.37–1.63) 0.506
 Dust exposure period
  1940- 13(40.6%) 19(59.4%) 1.00
  1960- 47(29.9%) 110(70.1%) 1.18(0.87–1.60) 0.286
  1980- 20(37.7%) 33(62.3%) 1.05(0.74–1.50) 0.793
 Age at first dust exposure
   < 18 9(33.3%) 18(66.7%) 1.00
  18–29 63(32.8%) 129(67.2%) 1.01(0.76~ 1.34) 0.286
   ≥ 30 8(34.8%) 15(65.2%) 0.98(0.66~ 1.46) 0.793
 Duration of dust exposure(years)
   < 10 1(14.3%) 6(85.7%) 1.00
  10- 21(38.9%) 33(61.1%) 0.71(0.49–1.03) 0.073
  20- 33(34.4%) 63(65.6%) 0.77(0.55~ 1.07) 0.119
  30- 25(29.4%) 60(70.6%) 0.82(0.59–1.15) 0.252
Environmental factors
 Workplace ventilation
  Well 46(41.1%) 66(58.9%) 1.00
  Poor 34(26.2%) 96(73.8%) 1.25(1.04–1.51) 0.017
 Accommodation
  Building 36(32.1%) 76(67.9%) 1.00
  Bungalow 44(33.8%) 86(66.2%) 0.98(0.82–1.16) 0.779
 Living spaceb
   < 20 21(29.2%) 51(70.8%) 1.00
  20–40 35(34.0%) 68(66.0%) 0.93(0.761–1.142) 0.497
  40- 6(23.1%) 20(76.9%) 1.10(0.873–1.381) 0.424
Behavioral factors
 Smoking
  Never 12(34.3%) 23(65.7%) 1.00
  Once 45(38.5%) 72(61.5%) 0.94(0.71–1.24) 0.497
  Occasionally 4(66.7%) 2(33.3%) 0.51(0.16–1.61) 0.424
  Frequently 19(22.6%) 65(77.4%) 1.18(0.90–1.54) 0.424
 Start smoking age
   < 18 14(31.8%) 30(68.2%) 1.00
   ≥ 18 51(32.3%) 107(67.7%) 0.99(0.79–1.25) 0.954
 Smoking indexc
  0 12(34.3) 23(65.7) 1
   > 0 21(36.2) 37(63.8) 0.99(0.73–1.35) 0.954
  15- 21(29.6) 50(70.4) 1.09(0.82–1.44) 0.566
  30- 23(31.9) 49(68.1) 1.05(0.79–1.40) 0.741
 Smoking years
   < 10 7(58.3%) 5(41.7%) 1.00
  10- 17(34.0%) 33(66.0%) 1.58(0.79–3.19) 0.197
   ≥ 30 40(29.0%) 98(71.0%) 1.70(0.87–3.36) 0.123
 Drinking
  Never 19(27.9%) 49(72.1%) 1.00
  Once 16(35.6%) 29(64.4%) 0.89(0.69–1.16) 0.405
  Occasionally 13(30.2%) 30(69.8%) 0.97(0.76–1.24) 0.797
  Frequently 32(37.2%) 54(62.8%) 0.87(0.70–1.09) 0.220
 Drinking indexd
  0 32(32.3) 67(67.7) 1
  1- 10(28.6) 25(71.4) 1.05(0.82–1.36) 0.672
  50- 15(30.6) 34(69.4) 1.02(0.81–1.29) 0.832
  100- 19(39.6) 29(60.4) 0.89(0.68–1.16) 0.404
 Days of every week of intake of fruits
   < 1 7(18.4%) 31(81.6%) 1.00
  1–3 27(35.5%) 49(64.5%) 0.79(0.63–0.99) 0.041
   ≥ 4 34(35.8%) 61(64.2%) 0.79(0.64–0.97) 0.028
 Days of every week of physical exercise
   < 1 2(40.0%) 3(60.0%) 1.00
  1- 11(28.9%) 27(71.1%) 1.18(0.56–2.49) 0.656
  7 60(33.3%) 120(66.7%) 1.11(0.54–2.29) 0.775
 Length of sleeping (hour)
   < 6 24(36.9%) 41(63.1%) 1.00
  6- 34(29.8%) 80(70.2%) 1.11(0.89–1.39) 0.345
   ≥ 8 22(34.9%) 41(65.1%) 1.03(0.80–1.34) 0.813
 History of BCG vaccination
  No 72(33.2%) 145(66.8%) 1.00
  Yes 8(32.0%) 17(68.0%) 1.02(0.77–1.35) 0.904
 The family history of tuberculosis
  No 78(33.5%) 155(66.5%) 1.00
  Yes 2(22.2%) 7(77.8%) 1.17(0.82–1.68) 0.396
 Exposure history of tuberculosis
  No 77(33.8%) 151(66.2%) 1.00
  Yes 3(21.4%) 11(78.6%) 1.19(0.89–1.58) 0.246
  1. QFT QuantiFERON-TB Gold In-Tube, CI Confidence Interval
  2. a Sum may not equal the total because of missing data
  3. bLiving space: average per-capita living space (m2)
  4. cSmoking index(pack-years): average number of packs of cigarettes smoked per day multiplied by the number of smoking years
  5. dDrinking index(50 g·year):grams of alcohol consumed daily multiplied by years of drinking