P1-178 Heterogeneity of the 23-valent pneumococcal polysaccharide vaccine efficacy due to various underlying conditions of chronic pulmonary disease in elderly patients

Introduction The efficacy of 23-valent pneumococcal polysaccharide vaccine (PPV23) against pneumonia in elderly with chronic illness remains controversial. Methods A total of 1378 elderly outpatients with chronic pulmonary disease were informed of the PPV23 efficacy on infectious pulmonary exacerbations. Individual patients who responded affirmatively were vaccinated between August and November 2002 and rest of them was assigned for control. The prevaccine period was defined as August 2001–August 2002. The events of interest were the first episode of bacterial pulmonary infection and death from any cause. The participants were observed for 2 years after vaccination. Results Frequent episodes of pulmonary infection in the prevaccine period increased the event rate significantly (no episode 17.3%, one episode 48.3%, more than one episode 74.6%, p<0.001, the Kaplan-Meier method). No significant differences of the survival probability were observed between the vaccinated and unvaccinated group during the analysis of the whole cohort. The mortality rate was higher in the vaccinated group (p<0.010). This was due to the higher vaccination rate in patients who had pulmonary infection during the prevaccine period (p<0.001). No harmful effects of PPV23 on mortality rate was seen (p=0.100) in the COX proportional hazards regression model. In subgroup analysis, PPV23 reduced event rate significantly only in patients with chronic respiratory failure who had not pulmonary infection during the prevaccine period (p<0.019). Conclusion The PPV23 needs to be given to elderly patients with chronic pulmonary disease at an earlier time where infectious complication in the lung has not occurred yet.