PPSV23 Pneumococcal Vaccine in Chronic Obstructive Pulmonary Disease (COPD)

Exacerbations are a common feature in moderate-to-severe chronic obstructive pulmonary disease (COPD). Morbidity, mortality and health-care costs of these patients largely result from exacerbations. The most common causes of an exacerbation are infection of tracheobronchial tree. Among them, Streptococcus pneumoniae is the most frequently isolated organism, accounting for 5-25% patients of COPD, while it is also the most commonly identified cause in community-acquired pneumonia (CAP), accounting for 16.5-38.9% of CAP patients.

In recent years, widespread emergence of antimicrobial resistance in Streptococcus pneumoniae has became a major global concern, especially in Taiwan, one of the highest levels of antibiotic-resistant pneumococci in the world. Therefore, primary prevention by vaccination is encouraged for those high-risk patients with COPD. The currently available adult pneumococcal vaccine consists of the capsular polysaccharide of 23 different serotypes of Streptococcus pneumoniae (PPSV23). The antibodies produced in response to this polysaccharide can provide protection by inducing host immune cells to kill or to opsonize bacteria for phagocytosis.

Until now, few studies have been designed to specifically examine vaccine efficacy in COPD patients. Among 3 available randomized controlled trials, only one study involving 596 patients found, from post-hoc analyses, some protective efficacy for pneumonia in patients of < 65 years of age and of an FEV1 < 40% predicted. Based on above evidence (only limited body of data), the Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2006 Guideline has recommended the PPSV23 inoculation as evidence B.

By the way, in comparison to placebo and the single components, a superior control by means of the inhaled corticosteroids (ICS)/long-acting beta2-agonist (LABA) fixed combination therapy has been demonstrated for significant clinical improvement in moderate-to-severe COPD patients, except mortality, by meta-analysis and large prospective studies (TORCH [Towards a Revolution in COPD Health] trial and INSPIRE [Investigating New Standards for Prophylaxis in Reduction of Exacerbations] trial). However, those database indicated that high daily dose of ICS (fluticasone propionate at a dose of 500-1000mcg daily) was associated with an excess risk of pneumonia, which doubles the pneumonia incidence in patients not receiving ICS. The immunogenicity of PPSV23 in COPD patients using systemic steroid was demonstrated but the clinical efficacy of vaccination has not been investigated.

From above-mentioned background, if the use of PPSV23 can reduce the incidence of pneumonia or exacerbations in COPD patients using high daily dose of ICS, the benefit of ICS can be preserved and risk of pneumonia can be reduced. For primary physicians, this hypothesis, if true, is very beneficial. So, in this study, the investigators want to conduct a double-blinded, randomized controlled trial to evaluate the clinical efficacy of PPSV23 in COPD patients using high daily dose of ICS.