Table 2.
Single model analysis for factors associated with hospital stay at index admission based on DAG
| Block | Variable | RR 95% CI | P value |
| Demographic characteristics | Age, per 5 years | 1.02 (1.00 to 1.03) | 0.032 |
| Male | 1.04 (0.96 to 1.12) | 0.312 | |
| Lung function and complications | FEV1 | 0.97 (0.95 to 1.00) | 0.055 |
| Respiratory failure | 1.05 (0.94 to 1.18) | 0.396 | |
| Pulmonary heart diseases | 1.03 (0.92 to 1.16) | 0.624 | |
| Hypoxemia | 0.96 (0.74 to 1.24) | 0.757 | |
| VTE | 1.38 (1.07 to 1.76) | 0.012* | |
| Pneumothorax | 1.63 (0.98 to 2.70) | 0.057 | |
| Hypoxic to hypercarbic encephalopathy | 1.53 (1.06 to 2.20) | 0.023* | |
| COPD comorbidities | Cardio/cerebrovascular diseases | 1.05 (0.98 to 1.13) | 0.184 |
| Diabetes | 0.98 (0.90 to 1.07) | 0.648 | |
| Respiratory infection | 1.12 (1.01 to 1.24) | 0.035* | |
| Bronchiectasis | 1.00 (0.88 to 1.13) | 0.967 | |
| Reflux oesophagitis | 1.00 (0.88 to 1.15) | 0.959 | |
| OSAS | 1.17 (0.97 to 1.42) | 0.094 | |
| Lung cancer | 1.09 (0.77 to 1.57) | 0.62 | |
| Anxiety depression | 0.89 (0.69 to 1.13) | 0.324 | |
| Osteoporosis | 1.45 (1.07 to 1.96) | 0.018* | |
| Obesity | 0.97 (0.86 to 1.08) | 0.559 | |
| Hospital factors | Admitted on Thursday–Sunday | 1.04 (0.97 to 1.11) | 0.319 |
| Admitted from emergency | 1.08 (1.01 to 1.16) | 0.033* | |
| Environmental factors | Season at admission, March–May | 1.01 (0.91 to 1.12) | 0.85 |
| Season at admission, June–August | 1.08 (0.96 to 1.22) | 0.176 | |
| Season at admission, September–November | 0.98 (0.88 to 1.09) | 0.752 | |
| O3, per 10 ug/m3 | 1.00 (0.995 to 1.01) | 0.573 | |
| PM2.5, per 10 ug/m3 | 1.00 (0.998 to 1.01) | 0.217 |
*P<0.05.
†
COPD, chronic obstructive pulmonary disease; DAG, directed acyclic graph; OSAS, obstructive sleep apnoea syndrome; Pre-FEV1, Pre-bronchodilator forced expiratory volume in one second; RR, rate ratio; VTE, venous thromboembolism.