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. Author manuscript; available in PMC: 2025 Jul 11.
Published in final edited form as: Chest. 2025 Jan 18;168(1):43–55. doi: 10.1016/j.chest.2024.12.037

Table 4.

Multivariate analysis of the association between 8-hour TWA endotoxin and quantitative small airway measures

8-hour TWA Endotoxina
(EU/m3)		 Exp−856 p-
Value		 E/I MLA p-
Value		 RVC−856 to −950 p-
Value		 Residual−856 p-
Value
All, N = 404
 Survey year 2011
  ≤ 50 - - - - - - - -
  50 - 1,500 −0.014 0.431 0.002 0.787 0.006 0.778 −0.002 0.901
  1,500 - 2,300 0.009 0.691 0.022 0.040 0.066 0.011 0.028 0.159
  2,300 - 3,900 −0.013 0.535 −0.010 0.333 −0.010 0.693 −0.016 0.421
  > 3,900 −0.007 0.765 0.009 0.411 0.024 0.380 0.013 0.538
 Survey Year 2016
  ≤ 50 - - - - - - - -
  50 - 1,500 −0.001 0.972 0.008 0.354 0.023 0.255 0.010 0.547
  1,500 - 2,300 0.019 0.390 0.023 0.035 0.071 0.006 0.033 0.100
  2,300 - 3,900 0.014 0.525 −0.003 0.754 0.009 0.719 0.012 0.532
  > 3,900 0.001 0.972 0.021 0.070 0.051 0.060 0.028 0.181
 Difference
  ≤ 50 - - - - - - - -
  50 - 1,500 0.013 0.435 0.006 0.507 0.018 0.385 0.012 0.487
  1,500 - 2,300 0.010 0.634 0.001 0.948 0.005 0.842 0.005 0.823
  2,300 - 3,900 0.027 0.193 0.007 0.508 0.019 0.444 0.028 0.171
  > 3,900 0.008 0.723 0.011 0.298 0.028 0.289 0.015 0.472
Cotton worker, N = 178
 Survey year 2011
  ≤ 50 - - - - - - - -
  50 – 1,500 0.033 0.412 0.039 0.036 0.087 0.060 0.055 0.126
  1,500 - 2,300 0.057 0.179 0.059 0.003 0.144 0.003 0.087 0.023
  2,300 - 3,900 0.033 0.453 0.030 0.143 0.080 0.107 0.042 0.276
  > 3,900 0.046 0.302 0.052 0.013 0.113 0.027 0.075 0.063
 Survey year 2016
  ≤ 50 - - - - - - - -
  50 - 1,500 0.052 0.202 0.050 0.008 0.114 0.014 0.075 0.038
  1,500 - 2,300 0.072 0.091 0.064 0.001 0.159 0.001 0.099 0.010
  2,300 - 3,900 0.065 0.137 0.041 0.041 0.109 0.028 0.079 0.044
  > 3,900 0.057 0.208 0.067 0.001 0.149 0.004 0.097 0.018
 Difference
  ≤ 50 - - - - - - - -
  50 – 1,500 0.019 0.602 0.010 0.520 0.028 0.492 0.020 0.560
  1,500 - 2,300 0.015 0.692 0.005 0.756 0.015 0.728 0.012 0.732
  2,300 - 3,900 0.032 0.386 0.012 0.484 0.030 0.484 0.036 0.312
  > 3,900 0.011 0.773 0.016 0.363 0.036 0.393 0.022 0.545

Note: Coefficients and p-Values from the linear mixed model with a random intercept were reported. p < 0.05 was considered significantly different from zero. SAD quantified by small airway measures was outcome and 8-hour TWA endotoxin was the exposure variable in the model. The linear mixed models were adjusted for age, gender, height, smoking intensity, survey year, and the interaction between 8-hour TWA endotoxin and survey year (8-hour TWA endotoxin × survey year). Abbreviations: TWA, Time-weighted Average; FEV1, Forced Expiratory Volume in the first 1 second; pp FEV1, percent predicted FEV1; FVC, Forced Vital Capacity; Exp−856, percent gas trapping; E/I MLA, expiratory to inspiratory ratio of mean lung attenuation; RVC−856 to 950, relative volume change of voxels with attenuation between −856 HU and −950 HU; Residual−856, residuals from the linear regression of Exp−856 on the percent of voxels with attenuation less than −950 HU.

a

50 EU/m3 represents the reference level. 1500 EU/m3 is the 40th percentile, 2300 EU/m3 is the 60th percentile, and 3900 EU/m3 is the 80th percentile. There are 237 textile workers exposed to ≤ 50 EU/m3 endotoxin, 61 workers exposed to 50 - 1,500 EU/m3 endotoxin, 35 workers exposed to 1,500 - 2,300 EU/m3 endotoxin, 37 workers exposed to 2,300 - 3,900 EU/m3 endotoxin, and 34 workers exposed to more than 3,900 EU/m3.