Effects of pulmonary infection during the prevaccine period and chronic respiratory failure on pulmonary infection-free survival after pneumococcal polysaccharide vaccine 23 vaccination
| Frequency of pulmonary infection during the prevaccine period | Chronic respiratory failure | N | Event* | Pulmonary infection-free survival at the end of the study* | 95% CI | p Value† |
| 0 | (−) | 1094 | 154 | 0.840 | 0.816 to 0.864 | <0.001 |
| 0 | (+) | 70 | 19 | 0.653 | 0.525 to 0.781 | |
| 1 | (−) | 147 | 59 | 0.550 | 0.462 to 0.638 | 0.506 |
| 1 | (+) | 20 | 10 | 0.409 | 0.168 to 0.649 | |
| >1 | (−) | 36 | 25 | 0.315 | 0.161 to 0.469 | 0.348 |
| >1 | (+) | 7 | 6 | 0.143 | 0.000 to 0.402 |
* Event represented the number of patients who were diagnosed as having pulmonary infection during the observation period.
† Data were analysed using the logrank test.