Multivariate cox regression analysis for time to death among the study population included in the validation cohort
| HR (95% CI) | p-value | |
| Hyaluronic acid | 1.019 (1.009–1.029) | <0.001 |
| Adjusted Charlson score | 1.207 (0.961–1.547) | 0.105 |
| Annual exacerbation rate | 1.306 (1.037–1.644) | 0.023 |
| BODE index | 1.268 (1.086–1.482) | 0.003 |
BODE: body mass, airflow obstruction, dyspnoea, exercise capacity.