Characteristics of the asymptomatic tobacco smokers and nonsmokers
| Nonsmokers | Smokers | p-value | |
| Young population n | 25 | 31 | |
| Age yrs | 29 (18–50) | 34 (21–50) | ns |
| Serum creatinine mg·dL−1 | 1.34 (0.99–1.76) | 1.36 (0.95–1.76) | ns |
| Cumulative smoking pack-yrs | 14.9 (2.5–54.0) | ||
| Current smoking cigarettes·day−1 | 19 (3.5–70) | ||
| Old population n | 44 | 23 | |
| Age yrs | 54 (50–60) | 54 (53–60) | ns |
| Serum creatinine mg·dL−1 | 1.05 (0.78–1.52) | 1.06 (0.79–1.37) | ns |
| Cumulative smoking pack-yrs | 30.8 (0.8–78.0) | ||
| Current smoking cigarettes·day−1 | 17 (1–40) | ||
| FEV1/VC | 0.85 (0.70–0.99) | 0.85 (0.70–0.92) | ns |
| 95th percentile | 0.69 (0.67–0.70) | 0.68 (0.67–0.70) | ns |
| VC | 4.40 (3.29–6.68) | 4.27 (2.91–5.42) | ns |
| % pred | 94 (73–132) | 89 (51–110) | ns |
| 95th percentile | 3.34 (2.19–3.96) | 3.27 (2.65–3.79) | ns |
| FVC | 3.94 (2.75–6.23) | 3.73 (2.28–5.02) | ns |
| % pred | 101 (78–136) | 96 (68–128) | ns |
| 95th percentile | 3.43 (2.19–4.09) | 3.36 (2.69–3.93) | ns |
| FEV1 | 3.32 (2.43–4.68) | 3.05 (1.87–3.99) | 0.04 |
| % pred | 99 (71–125) | 93 (53–119) | ns |
| 95th percentile | 2.56 (1.7–3.02) | 2.53 (2.02–2.93) | ns |
| PEF | 462 (239–614) | 445 (263–577) | ns |
| % pred | 92 (47–126) | 96 (50–111) | ns |
| 95th percentile | 311 (235–350) | 308 (263–342) | ns |
| FEF25 | 6.69 (2.41–9.89) | 5.84 (2.67–8.19) | ns |
| % pred | 91 (32–136) | 65 (35–107) | ns |
| FEF50 | 4.43 (2.42–7.07) | 3.60 (1.73–5.27) | 0.005 |
| % pred | 93 (55–166) | 84.5 (37–112) | ns |
| FEF75 | 1.66 (0.76–3.19) | 1.41 (0.53–2.95) | 0.03 |
| % pred | 88 (40–200) | 79 (33–164) | ns |
| FEF25–75 | 5.02 (2.41–8.22) | 4.87 (1.52–6.42) | ns |
| % pred | 90 (40–147) | 87 (27–114) | ns |
| 95th percentile | 3.92 (3.37–4.32) | 3.93 (3.61–4.12) | ns |
Data are presented as median (range)
The data have been stratified into those that underwent lung function testing (old population, age ≥50 yrs) and those that did not (young population, age <50 yrs)
FEV1: forced expiratory volume in one second
VC: vital capacity: FVC: forced VC
PEF: peak expiratory flow
FEF25, FEF50, FEF75: forced expired flow measured with a peak flow meter at 25%, 50% and 75% of expired volume respectively
FEF25–75: average forced expired flow between 25% and 75% of expired volume
% pred: percentage predicted
The associated 5th percentiles (95th percentile) that define the lower limits of normal are shown for FEV1/VC, VC, FVC, PEF, and FEF25–75
Significant and nonsignificant (ns) differences between the nonsmokers and smokers are depicted