Statin for Pneumonia and Influenza - Systematic Review and Meta-Analysis to Inform Policy to Mitigate COVID-19

Objectives: We examined the role of statins in influenza and pneumonia associated mortality and morbidity to inform policy for mitigating COVID-19. Methods: Systematic search of electronic databases and hand searching of full text references published up to 14 April 2021 were undertaken. Studies that explored the effectiveness of statins (HMG-CoA reductase inhibitors) on influenza and/or pneumonia were included in this systematic review. Quality of the included studies was assessed by an appropriate tool like ‘risk of bias’s assessment tool of the Cochrane Handbook for randomised controlled trials (RCTs) and Newcastle-Ottawa Scale (NOS) for observational studies. Protocol was registered with Cochrane: https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD008916/full. Results: We included 37 papers with 38 studies with a total of 56,64,917 participants, of those 23 publications with a pooled sample of 521,511 were included in meta-analysis. Of the 37 included articles, there were 27 cohort studies, six case control studies, three RCTs and one having both cohort and case control components. Our aggregated data suggest that the use of statins had favorable effects on pneumonia 30-day mortality (RR 0.72, 95% CI 0.59 to 0.88), pneumonia in-hospital mortality (RR 0.68, 95% CI 0.63 to 0.72) and pneumonia long-term all-cause mortality (RR 0.65, 95% CI 0.57to 0.73) but no benefit was detected for hospitalisation (OR 1.29, 95% CI 0.88 to 1.90) intensive care unit (ICU) admission (RR 0.89, 95% CI 0.70 to 1.12) for pneumonia. Conclusions: Statin use appears to reduce pneumonia mortality via their anti-inflammatory and immunomodulatory capability but their effectiveness on influenza remains uncertain. The use of statins in COVID-19 warrants further in-depth investigation including RCTs. Funding Statement: None. Declaration of Interests: None declared.