Table 2.
Unadjusted Correlations Between Quantitative Small Airway Measures, Spirometry, and 8-Hour TWA Endotoxin
| 8-Hour TWA Endotoxin |
||||
|---|---|---|---|---|
| 2011 (n = 404) | P Value | 2016 (n = 404) | P Value | |
| Small airway measures | ||||
| Exp−856 | 0.053 | .288 | 0.113 | .023 |
| E/I MLA | 0.060 | .229 | 0.117 | .019 |
| RVC−856 to −950 | 0.065 | .191 | 0.127 | .011 |
| Residual−856 | 0.066 | .187 | 0.135 | .007 |
| Spirometry | ||||
| FEV1 | 0.044 | .380 | 0.027 | .583 |
| pp FEV1 | –0.187 | < .001 | –0.184 | < .001 |
| FEV1/FVC | –0.145 | .004 | –0.118 | .017 |
Pearson correlation coefficients are reported. P < .05 was considered significantly different from zero. E/I MLA = expiratory-to-inspiratory ratio of mean lung attenuation; Exp−856 = percentage of voxels with attenuation less than -856 HU on expiratory CT scans; HU = Hounsfield unit; pp FEV1 = percent predicted FEV1; Residual–856 = residuals from the linear regression of Exp−856 on the percentage of voxels with attenuation less than –950 HU; RVC−856 to −950 = relative volume change in voxels with attenuation between –856 HU and –950 HU; TWA = time-weighted average.