Table 4. Prognostic factors related to recurrence.
| Variables | Univariable Cox analysis | Multivariable Cox analysis | |||
|---|---|---|---|---|---|
| Unadjusted HR (95% CI) | P | Adjusted HR (95% CI) | P | ||
| Age, years | 0.992 (0.932–1.056) | 0.803 | 0.940 (0.878–1.007) | 0.076 | |
| Sex, male | NA | – | – | – | |
| Body mass index, kg/m2 | 0.963 (0.822–1.127) | 0.638 | – | – | |
| Height, cm | 0.950 (0.882–1.022) | 0.170 | 0.935 (0.853–1.024) | 0.146 | |
| Smoking history | |||||
| Former smoker | Reference | – | – | – | |
| Current smoker | 0.895 (0.246–3.250) | 0.866 | – | – | |
| Laboratory findings | |||||
| C-reactive protein, mg/dL | 1.006 (0.933–1.085) | 0.881 | – | – | |
| Albumin, g/dL | 0.917 (0.390–2.161) | 0.844 | – | – | |
| Partial pressure of carbon dioxide, mmHg | 1.041 (1.002–1.081) | 0.040 | – | – | |
| Type of emphysema on computed tomography | |||||
| Centrilobular or paraseptal | Reference | – | – | – | |
| Combined centrilobular and paraseptal | 1.241 (0.438–3.518) | 0.684 | – | – | |
| Treatment | |||||
| Tube thoracostomy alone | 3.494 (0.452–27.007) | 0.231 | 3.427 (0.437–26.891) | 0.241 | |
| Tube thoracostomy and additional interventions* | Reference | – | Reference | – | |
| Pulmonary function tests after recovery from pneumothorax | |||||
| FVC, L | 0.495 (0.208–1.175) | 0.111 | – | – | |
| FEV1, L | 0.477 (0.228–0.997) | 0.049 | 0.408 (0.186–0.896) | 0.025 | |
Data are presented as hazard ratio (HR) with 95% confidence intervals (CI). *, additional interventions refer to chemical pleurodesis. HR, hazard ratio; CI, confidential interval; FVC, forced vital capacity; FEV1, forced expiratory volume in 1 second.