title: Statins and primary prevention of venous thromboembolism: a systematic review and meta-analysis.
abstract: BACKGROUND
  Statins have been suggested to have a protective effect on venous thromboembolism (which includes deep vein thrombosis and pulmonary embolism), but the evidence is uncertain. We sought to evaluate the extent to which statins are associated with first venous thromboembolism events.
  
  
  METHODS
  We did a systematic review and meta-analysis of observational cohort studies and randomised controlled trials (RCTs). Relevant studies that reported associations between statins and first venous thromboembolism outcomes were identified from MEDLINE, Embase, Web of Science, Cochrane Library, and a manual search of bibliographies for studies published up until July 18, 2016, and from email correspondence with investigators. Observational cohorts that assessed the association of statin use with venous thromboembolism, deep vein thrombosis, or pulmonary embolism in adults were included, as were intervention studies that assessed the effects of statin therapy compared with a placebo or no treatment and collected data on venous thromboembolism, deep vein thrombosis, or pulmonary embolism outcomes. Studies that compared statins with another statin or lipid-lowering agent were excluded. Study specific relative risks (RRs) were aggregated using random-effects models and were grouped by study-level characteristics. The review has been registered with PROSPERO, number CRD42016035622.
  
  
  RESULTS
  36 eligible studies (13 cohort studies comprising 3 148 259 participants and 23 RCTs of statins vs placebo or no treatment comprising 118 464 participants) were included. In observational studies, the pooled RR for venous thromboembolism was 0·75 (95% CI 0·65-0·87; p<0·0001) when statin use was compared with no statin use. This association remained consistent when grouped by various study-level characteristics. In RCTs, the RR for venous thromboembolism was 0·85 (0·73-0·99; p=0·038) when statin therapy was compared with placebo or no treatment. Subgroup analyses suggested significant differences in the effect of statins by type of statin, with rosuvastatin having the lowest risk on venous thromboembolism compared with other statins 0·57 (0·42-0·75; p=0·015). There was no evidence of an effect of statin use on pulmonary embolism. Statin use was associated with a significant reduction in risk of the specific endpoint of deep vein thrombosis compared with no statin use (RR 0·77, 95% CI 0·69-0·86; p<0·0001).
  
  
  CONCLUSIONS
  Available evidence from observational and intervention studies suggest a beneficial effect of statin use on venous thromboembolism. In intervention studies, therapy with rosuvastatin significantly reduced venous thromboembolism compared with other statins. Further evidence is however needed to validate these findings.
  
  
  BACKGROUND
  None.
authors.affiliation: School of Clinical Sciences, University of Bristol, Southmead Hospital, Bristol, UK. Electronic address: skk31@cantab.net.
authors.forename: Setor K
authors.initials: SK
authors.lastname: Kunutsor
authors.affiliation: Leicester Diabetes Centre, and Diabetes Research Centre, University of Leicester, Leicester General Hospital, Leicester, UK.
authors.forename: Samuel
authors.initials: S
authors.lastname: Seidu
authors.affiliation: Leicester Diabetes Centre, and Diabetes Research Centre, University of Leicester, Leicester General Hospital, Leicester, UK.
authors.forename: Kamlesh
authors.initials: K
authors.lastname: Khunti
mesh_terms: D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use*; D011322:Primary Prevention; D054556:Venous Thromboembolism / Q000517:prevention & control*
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors