Overall | Australia | Israel | Spain | USA | P value* | |
N=169 | N=14 | N=125 | N=20 | N=10 | ||
Pulmonary function testing measurements, mean (SD)† | ||||||
FEV1, % predicted (n=147) | 66.4±26.6 | 84.6±13.4 | 58.4±25.7 | 89.8±14.9 | 91.6±14.9 | <0.0001 IA, IS, US |
FVC, % predicted (n=147) | 70.9±24.6 | 87.6±13.1 | 63.8±23.5 | 91.9±14.9 | 93.3±17.3 | <0.0001 IA, IS, US |
FEV1/FVC, % (n=147) | 73.6±13.5 | 79.4±8.0 | 71.7±14.9 | 78.2±4.0 | 78.6±6.6 | 0.0474 |
TLC, % predicted (n=129) | 84.9±23.3 | 87.5±15.8 | 83.0±23.9 | 93.3±4.6 | 99.3±22.0 | 0.1648 |
DLCO, % predicted (n=137) | 75.0±27.8 | 86.1±14.2 | 68.1±26.4 | 93±20.2 | 108±28.1 | <0.0001 IU, IS |
Abnormal pulmonary function testing, n (%)† | ||||||
Restrictive‡ | 35/128 (27.3) | 2/11 (18.2) | 32/104 (30.8) | 0/3 (0.0) | 1/10 (10.0) | 0.3861 |
Obstructive§ | 33/142 (23.2) | 1/14 (7.1) | 31/105 (29.5) | 0/13 (0.0) | 1/10 (10.0) | 0.0206IS |
Mixed¶ | 12/128 (9.4) | 0/11 (0.0) | 12/104 (11.5) | 0/3 (0.0) | 0/10 (0.0) | 0.6816 |
Normal** | 62/147 (42.2) | 11/14 (78.6) | 30/108 (27.8) | 13/15 (86.7) | 8/10 (80.0) | <0.0001 IA, IS, IU |
Reduced TLC†† | 50/129 (38.0) | 2/11 (18.2) | 47/105 (44.8) | 0/3 (0.0) | 1/10 (10.0) | 0.0287IU |
Reduced DLCO‡‡ | 63/137 (46.0) | 4/14 (28.6) | 56/101 (55.5) | 2/12 (16.7) | 1/10 (10.0) | 0.0016 IU, IS |
Hypoxaemia | 39/166 (23.5) | 0/14 (0.0) | 36/122 (29.5) | 0/20 (0.0) | 3/10 (30.0) | 0.0009IA, IS, US |
*One-way ANOVA for continuous variables and Fisher’s exact test for cross-country comparison of categorical variables; individual comparisons: A=Australia, I=Israel, S=Spain, U=USA.
†Pulmonary function tests included measurements of FEV1, FVC, the ratio of FEV1/FVC, TLC, DLCO. Global lung Initiative reference values were used for FEV1, FVC, FEV1/FVC, DLCO and LLN for all parameters.
‡Restrictive defined as FEV1/FVC ratio ≥LLN, FVC <LLN and TLC <LLN.
§Obstructive defined as a FEV1/FVC ratio <LLN and FVC ≥LLN; or FEV1/FVC ratio ≥LLN, FVC <LLN and TLC ≥LLN; or FEV1/FVC ratio <LLN, FVC <LLN and TLC ≥LLN.
¶Mixed defined as FEV1/FVC ratio <LLN, FVC <LLN and TLC <LLN.
**Normal defined as FEV1/FVC ratio ≥LLN and FVC ≥LLN.
††Reduced TLC defined as a measured TLC value <LLN.
‡‡Reduced DLCO defined as a measured DLCO value <LLN.
ANOVA, analysis of variance; DLCO, diffusion capacity of lung for carbon monoxide; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; LLN, lower limits of normal ; TLC, total lung capacity.