A Meta-analysis of Randomized Controlled Trials

containing pneumococcal antigen types only (vaccine types only) (OR=0.17; 95% CI=0.09 to 0.33), presumptive pneumococcal pneumonia (OR=0.47; 95% CI=0.35 to 0.63), and presumptive pneumococcal pneumonia (vaccine types only) (OR=0.39; 95% CI=0.26 to 0.59). The summary RDs, which account for heterogeneity among studies, confirmed a statistically significant protective effect for two of these same outcomes: definitive pneumococcal pneumonia (RD=4/1000; 95% CI=0/1000 to 7/1000) and definitive pneumococcal pneumonia (vaccine types only) (RD=8/1000; 95% CI=1/1000 to 16/1000). Summary ORs and RDs failed to demonstrate a protective effect for pneumonia (all causes), bronchitis, and mortality (all causes) or mortality due to pneumonia or pneumococcal infection. Subgroup analyses showed that for all four pneumococcal infection\p=m-\relatedoutcomes, vaccine efficacy differed for high- and low-risk subjects, demonstrating efficacy for low-risk subjects and lack of efficacy for high-risk subjects. Conclusions: Pneumococcal vaccination appears efficacious in reducing bacteremic pneumococcal pneumonia in low-risk adults. However, evidence from randomized controlled trials fails to demonstrate vaccine efficacy for pneumococcal infection\x=req-\relatedor other medical outcomes in the heterogeneous group of subjects currently labeled as high risk. (Arch Intern Med. 1994;154:2666-2677) _I_ Illness DUE to Streptococcus pneu