| Variable | Aging % (n) | Young-adult % (n) | p-value |
| Allergy | 8.4 (8) | 4.0 (1) | 0.455 |
| Comorbidity | 27.4 (26) | 12.0 (3) | 0.110 |
| Type of comorbidities |
|
| 0.395 |
| • Cardiovascular disease | 15.8 (15) | 4.0 (1) |
|
| • Diabete millitus | 1.1 (1) | 0 (0) |
|
| • Association of cardiovascular disease and diabetes mellitus | 4.2 (4) | 0 (0) |
|
| • Interstitial lung disease | 6.3 (6) | 8.0 (2) |
|