Table 2.
Effect estimates of listed parameters on baseline % lung volume <-950 HU values
| Parameter | Effect size | p-value. |
95% CI of effect size |
|
|---|---|---|---|---|
| Lower bound | Upper bound | |||
|
Center |
|
|
|
|
| UMCU |
0.87 |
<0.001 |
0.83 |
0.91 |
| UMCG (reference) |
|
|
|
|
|
smoking group |
|
|
|
|
| current smoker |
0.60 |
<0.001 |
0.56 |
0.64 |
| quitted <1 year |
0.90 |
0.033 |
0.81 |
0.99 |
| quitted ≥1 – <5 years |
0.99 |
0.956 |
0.93 |
0.99 |
| quitted ≥5years (reference) |
|
|
|
|
|
baseline GOLD stage |
|
|
|
|
| normal |
0.17 |
0.013 |
0.04 |
0.68 |
| stage I |
0.26 |
0.065 |
0.06 |
1.08 |
| stage II |
0.29 |
0.089 |
0.07 |
1.21 |
| stage III |
0.46 |
0.279 |
0.11 |
1.89 |
| stage IV (reference) |
|
|
|
|
|
Presence of respiratory symptoms |
|
|
|
|
| cough |
0.87 |
0.980 |
0.82 |
0.91 |
| wheezing |
0.97 |
0.449 |
0.90 |
1.05 |
| dyspnea |
1.00 |
0.786 |
0.94 |
1.08 |
| mucus |
1.02 |
0.568 |
0.95 |
1.09 |
|
height (cm) |
1.01 |
<0.001 |
1.01 |
1.02 |
|
age at start study (years) |
1.02 |
<0.001 |
1.01 |
1.02 |
| packyears | 0.99 | <0.001 | 0.99 | 1.00 |
The column headed with ‘effect size’ gives the change in % lung volume <-950 HU due to a unit change in the parameter or due to membership of another class. So for each year a subject is older at the start of the study, the % lung volume <-950 HU increases with a factor or1.02 per year. For class comparisons the changes are versus the reference group: so a subject with an FEV1/FVC >70% (no COPD) has 0.17 times lower % lung volume <-950 HU compared to the reference GOLD class 4 (the p-value for this comparison is <0.001).