Lifestyle risk factors for invasive pneumococcal disease: a systematic review

OBJECTIVE: To systematically review the literature for evidence of smoking and alcohol intake as independent risk factors for invasive pneumococcal disease (IPD). DESIGN: Systematic review. METHODS: MEDLINE (1946—May 2012) and EMBASE (1947—May 2012) were searched for studies investigating alcohol or smoking as risk factors for acquiring IPD and which reported results as relative risk. Studies conducted exclusively in clinical risk groups, those assessing risk factors for outcomes other than acquisition of IPD and studies describing risk factors without quantifying a relative risk were excluded. RESULTS: Seven observational studies were identified and reviewed; owing to the heterogeneity of study design, meta-analysis was not attempted. Five of six studies investigating smoking reported an increased risk of IPD in the range 2.2–4.1. Four of the six studies investigating alcohol intake reported a significant increased risk for IPD ranging from 2.9 to 11.4, while one reported a significant protective effect. CONCLUSIONS: Overall, these observational data suggest that smoking and alcohol misuse may increase the risk of IPD in adults, but the magnitude of this risk remains unclear and should be explored with further research. The findings of this review will contribute to the debate on whether pneumococcal vaccine should be offered to smokers and people who misuse alcohol in addition to other clinically defined risk groups.