Clinical, functional and radiographic measurements of asymptomatic ex-smokers with normal and abnormal diffusion capacity of the lung for carbon monoxide, compared with GOLD stage I chronic obstructive pulmonary disease
| ND (n=19) | AD (n=19) | Stage I COPD (n=15) | Significance of difference (p) | ||
|---|---|---|---|---|---|
| ND–AD | AD–COPD | ||||
| Subject demographics | |||||
| Age (years) | 71 (7) | 74 (7) | 77 (5) | 0.09 | 0.30 |
| No of women (n) | 3 | 11 | 2 | 0.02 | 0.01 |
| BMI (kg/m2) | 29.5 (3.4) | 28.6 (4.0) | 28.4 (4.0) | 0.46 | 0.91 |
| Pack-years | 25 (12) | 32 (23) | 49 (36) | 0.25 | 0.11 |
| Time since quitting (years) | 26 (9) | 24 (14) | 21 (14) | 0.63 | 0.63 |
| Pulmonary function tests | |||||
| FEV1%pred | 107 (13) | 99 (12) | 95 (13) | 0.07 | 0.34 |
| FVC %pred | 98 (12) | 93 (12) | 108 (14) | 0.16 | 0.001 |
| FEV1/FVC | 80 (6) | 80 (7) | 63 (5) | 0.73 | <0.0001 |
| IC %pred | 112 (17) | 103 (22) | 103 (17) | 0.17 | 0.99 |
| RV %pred | 103 (17) | 107 (25) | 114 (29) | 0.58 | 0.45 |
| TLC %pred | 101 (10) | 101 (15) | 109 (13) | 0.96 | 0.12 |
| RV/TLC %pred | 101 (13) | 104 (16) | 103 (18) | 0.49 | 0.77 |
| DLCO %pred | 89 (9) | 59 (13) | 68 (19) | <0.0001 | 0.12 |
| 6MWT | |||||
| Pre 6MWT SpO2% | 97 (2) | 95 (2) | 95 (2) | 0.06 | 0.57 |
| Δ 6MWT SpO2% | 0 (2)* | 0 (2)† | −1 (3) | 0.55 | 0.25 |
| Distance (m) | 430 (99) | 341 (95) | 417 (41) | 0.008 | 0.005 |
| SGRQ | |||||
| Symptoms | 18 (17)* | 36 (30)* | 36 (22) | 0.04 | 0.99 |
| Activity score | 19 (21)† | 41 (24) | 36 (25)‡ | 0.006 | 0.54 |
| Impact score | 6 (11)† | 17 (18) | 15 (13)‡ | 0.04 | 0.68 |
| Total score | 12 (14)§ | 29 (21) * | 25 (17)‡ | 0.01 | 0.59 |
| CT measurements | |||||
| RA950 | 1.36 (1.25) | 1.60 (1.06) | 5.50 (3.16) | 0.53 | 0.0008 |
| WA% | 57 (4) | 59 (2) | 58 (2) | 0.17 | 0.23 |
| 3He MRI measurements | |||||
| ADC (cm2/s) | 0.27 (0.03)* | 0.30 (0.03)§ | 0.36 (0.08) | 0.01 | 0.02 |
| VDP (%) | 6 (3)* | 7 (4)§ | 9 (5)‡ | 0.40 | 0.07 |
Values are mean (SD).
Missing values: SpO2 not recorded post-6MWT (n=1, normal DLCO; n=2, abnormal DLCO); incomplete SGRQ questionnaire (n=3, normal DLCO; n=1, abnormal DLCO; n=1, COPD); and image acquisition failures (n=1, normal DLCO; n=2, abnormal DLCO; n=1, COPD).
*n=18, †n=17, ‡n=14, §n=16.
AD, abnormal DLCO; ADC, apparent diffusion coefficient; BMI, body mass index; COPD, chronic obstructive pulmonary disease; DLCO, diffusion capacity of the lung for carbon monoxide; FEV1, forced expiratory volume in 1 s; FVC, force vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease; IC, inspiratory capacity; 6MWT, 6 min Walk Test; ND, normal DLCO; RA950, relative area with attenuation values below −950 HU; RV, residual volume; SGRQ, St George's Respiratory Questionnaire; SpO2, peripheral oxygen saturation; TLC, total lung capacity; VDP, ventilation defect per cent; WA%, wall area per cent.