Purpose: Influenza is a threat to patients with chronic obstructive pulmonary disease (COPD), influenza vaccination help to reduce incidence of influenza infection, however, whether it is beneficial to COPD patients in clinical outcomes lacks for evidence due to limited studies and participations.
Methods: We searched PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI) and China Science and Technology Journal Database (CSTJ) to retrieve eligible studies regardless of study design published before August 2020, and conducted meta-analysis with odds ratio (OR) and mean difference (MD). The quality of included studies and pooled evidences were assessed. Narrative summaries were provided where data were insufficient for meta-analysis.
Results: 2831 COPD patients were included, the pooled results showed that influenza vaccination reduced the exacerbations (P = 0.0001) and trends of hospitalizations (P = 0.09) in COPD patients. Further subgroup analysis showed that the reduction of exacerbations and hospitalizations were significant in patients with FEV1<50 % predicted (P = 0.01 and P < 0.0001 respectively), but not in those with FEV1≥50 % predicted (P = 0.23 and P = 0.76 respectively). No significant effect of influenza vaccination on all-cause mortality was observed.
Conclusions: Our findings support a protective role of influenza vaccination in COPD patients, a yearly influenza vaccination should be strongly recommended for all COPD patients, especially those with severe airflow limitation, to reduce possible influenza infection, and thus associated exacerbations and hospitalizations.
Keywords: Acute exacerbation; All-cause mortality; Chronic obstructive pulmonary disease; Forced expiratory volume in 1 second; Hospital admissions; Influenza vaccination.
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