Demographics and pulmonary function characteristics of discharged patients with COVID-19
| Total | Mild illness | Pneumonia | Severe pneumonia | p-value | |
| Patients | 110 | 24 | 67 | 19 | |
| Age years | 49.1±14.0 | 46.8±15.6 | 47.9±13.7 | 56.5±11.0*,# | 0.04 |
| Female | 55 (50.0) | 13 (54.2) | 36 (53.7) | 6 (31.6) | 0.21 |
| Smoker | 13 (11.8) | 4 (16.7) | 7 (10.4) | 2 (10.5) | 0.707 |
| BMI kg·m−2 | 23.5±3.0 | 23.1±2.8 | 23.6±3.2 | 23.5±2.7 | 0.794 |
| Duration from onset to discharge days | 27±9 | 20±6 | 29±8** | 34±7**,# | <0.001 |
| Underlying disease | 44 (40.0) | 10 (41.7) | 25 (37.3) | 9 (47.4) | 0.719 |
| Lung disease | 3 (2.7) | 0 (0) | 3 (4.5) | 0 (0) | 1 |
| Heart disease | 3 (2.7) | 1 (4.2) | 2 (3.0) | 0 (0) | 1 |
| Hypertension | 26 (23.6) | 6 (25.0) | 15 (22.4) | 5 (26.3) | 0.924 |
| Cerebrovascular disease | 3 (2.7) | 0 (0) | 2 (3.0) | 1 (5.3) | 0.532 |
| Diabetes | 9 (8.2) | 1 (4.2) | 6 (9.0) | 2 (10.5) | 0.702 |
| Liver disease | 6 (5.5) | 2 (8.3) | 3 (4.5) | 1 (5.3) | 0.837 |
| Kidney disease | 2 (1.8) | 1 (4.2) | 1 (1.5) | 0 (0) | 0.631 |
| Solid tumour | 1 (0.9) | 0 (0) | 0 (0) | 1 (5.3) | 0.173 |
| SpO2 on discharge % | 98.7±1.0 | 98.6±1.2 | 98.7±1.0 | 98.5±1.0 | 0.73 |
| Spirometry | |||||
| FVC % pred | 93.59±12.25 | 94.06±10.48 | 94.12±12.31 | 91.12±14.30 | 0.632 |
| FVC <80% pred | 10 (9.09) | 3 (12.50) | 5 (7.46) | 2 (10.53) | 0.644 |
| FEV1 % pred | 92.70±11.57 | 94.26±11.00 | 92.59±11.87 | 91.12±11.58 | 0.676 |
| FEV1 <80% pred | 15 (13.64) | 4 (16.67) | 9 (13.43) | 2 (10.53) | 0.857 |
| FEV1/FVC % | 80.70±5.81 | 81.84±5.48 | 80.39±6.12 | 80.19±5.15 | 0.509 |
| FEV1/FVC <70% | 5 (4.55) | 0 (0) | 5 (7.46) | 0 (0) | 0.349 |
| MMEF % pred | 97.40±26.23 | 99.77±28.17 | 96.59±26.51 | 96.14±23.82 | 0.879 |
| MMEF <65% pred¶ | 7 (6.42) | 1 (4.17) | 6 (9.09) | 0 (0) | 0.551 |
| FEF50% % pred | 94.74±26.11 | 97.47±25.48 | 94.09±26.80 | 93.53±25.56 | 0.845 |
| FEF50% <65% pred¶ | 12 (11.01) | 2 (8.33) | 8 (12.12) | 2 (10.53) | 1 |
| FEF75% % pred | 96.10±32.56 | 102.23±40.20 | 95.02±30.89 | 92.08±27.92 | 0.549 |
| FEF75% <65% pred¶ | 12 (11.01) | 3 (12.50) | 4 (6.06) | 5 (26.32)# | 0.035 |
| Diffusion capacity | |||||
| DLCO % pred | 78.18±14.29 | 84.70±13.88 | 79.76±11.99 | 64.79±14.35**,## | <0.001 |
| DLCO <80% pred | 51 (47.22) | 7 (30.43) | 28 (42.42) | 16 (84.21)**,## | 0.001 |
| DLCO/VA % pred | 92.09±16.68 | 99.35±18.25 | 92.30±15.70 | 82.58±13.91**,# | 0.004 |
| DLCO/VA <80% pred | 29 (26.85) | 3 (13.04) | 18 (27.27) | 8 (42.11) | 0.09 |
| Lung volume | |||||
| TLC % pred | 86.32±11.32 | 87.13±10.43 | 88.11±10.72 | 79.16±12.13*,## | 0.008 |
| TLC <80% pred | 27 (25.00) | 4 (17.39) | 14 (21.21) | 9 (47.37)*,# | 0.049 |
| RV % pred | 86.83±19.37 | 87.17±16.88 | 89.79±19.21 | 76.16±19.96## | 0.024 |
| RV <65% pred | 10 (9.26) | 2 (8.70) | 3 (4.55) | 5 (26.32)# | 0.021 |
| RV/TLC % pred | 96.99±16.72 | 98.00±14.93 | 98.53±17.55 | 90.42±14.86 | 0.168 |
Data are presented as n, mean±sd or n (%), unless otherwise stated. Comparisons between continuous variables were performed with one-way ANOVA. Chi-squared test and Fisher's exact test were applied to categorical variables as appropriate. BMI: body mass index; SpO2: oxygen saturation measured by pulse oximetry; FVC: forced vital capacity; FEV1: forced expiratory volume in 1 s; MMEF: maximal mid-expiratory flow; FEF50%: forced expiratory flow at 50% of FVC; FEF75%: forced expiratory flow at 75% of FVC; DLCO: diffusing capacity of the lung for carbon monoxide; DLCO/VA: DLCO corrected for alveolar volume; TLC: total lung capacity; RV: residual volume. *: p<0.05 versus mild illness; **: p<0.01 versus mild illness; #: p<0.05 versus pneumonia; ##: p<0.01 versus pneumonia; ¶: at least two of these <65% pred defined patients with small airway function anomalies.