Parameters | Low altitude | After arrival | Day 3 | 3 months | 6 months | Pa | Pb |
VC (l) | SMO 4.48±0.46 | SMO 4.36±0.63 | SMO 4.24±0.60 | SMO 4.12±0.62 | SMO 4.10±0.38 | 0.046 | G: 0.110 |
CON 4.54±0.44 | CON 4.43±0.45 | CON 4.12±0.63 | CON 4.52±0.32* | CON 4.50±0.26† | 0.013 | I: 0.027 | |
FEV1 (l) | SMO 3.92±0.82 | SMO 3.98±0.74 | SMO 4.02±0.84 | SMO 3.96±0.78 | SMO 3.82±0.74 | 0.321 | G: 0.164 |
CON 4.10±0.48 | CON 4.21±0.51 | CON 4.18±0.62 | CON 4.28±0.46‡ | CON 4.22±0.50‡ | 0.388 | I: 0.465 | |
FEF25–75% (litres/s) | SMO 4.08±1.05 | SMO 4.01±0.85 | SMO 4.06±1.06 | SMO 4.02±1.12 | SMO 3.92±0.92 | 0.465 | G: 0.044 |
CON 4.16±0.85 | CON 4.24±0.66 | CON 4.28±0.72 | CON 4.81±0.63§ | CON 4.93±0.67¶ | 0.006 | I: 0.048 | |
MVV (litres/min) | SMO 108.0±4.5 | SMO 110.2±4.4 | SMO 111.6±4.8 | SMO 106.3±5.2 | SMO 107.4±5.3 | 0.035 | G: 0.002 |
CON 111.3±5.2 | CON 115.5±5.6** | CON 117.4±4.6** | CON 118.3±3.8** | CON 117.8±4.5** | 0.002 | I: 0.001 |
Data are presented as mean ± SD. Pa: ANOVA for repeated measures within each group separately. Pb: ANOVA—probabilities between groups (G), and interaction (I). Group comparisons: *SMO versus CON, p<0.001; †SMO versus CON p<0.001, ‡SMO versus CON, p=0.048 and p=0.036; §SMO versus CON, p=0.048; ¶SMO versus CON, p=0.021; **SMO versus CON, p<0.001.
Because of technical problems only a subset of subjects had pulmonary function tests: at low altitude 40 (SMO) and 42 (CON), after arrival 36 (SMO) and 28 (CON), at 3 days 36 (SMO) and 28 (CON), at 3 months 32 (SMO) and 34 (CON) and at 6 months 28 (SMO) and 25 (CON). The measurements reported concern the same subjects over time.
SMO, smoking group; CON, control group; VC, vital capacity; FEV1, forced expiratory volume in 1 s; FEF25-75% forced expiratory flow between 25% and 75% of vital capacity; MVV, maximal voluntary ventilation.