LAUSR

Objective To synthesise evidence from exclusively primary prevention data on the effectiveness of statins for prevention of cardiovascular disease (CVD), including stroke, and outcomes stratified by baseline risk and gender. Design Overview of systematic reviews (SRs) using Revised-AMSTAR approach to assess quality. Data sources Cochrane Database of Systematic Reviews, MEDLINE, Embase, PubMed, Scopus and PROSPERO to June 2017. Eligibility criteria for selecting studies SRs of randomised control trials (RCTs) or individual patient data (IPD) from RCTs, examining the effectiveness of statins versus placebo or no treatment on all-cause mortality, coronary heart disease, CVD (including stroke) and composite endpoints, with stratification by baseline risk and gender. Data extraction and synthesis Two independent reviewers extracted data and assessed methodological quality. A narrative synthesis was conducted. Results Three SRs were included. Quality of included SRs was mixed, and none reported on the risk of bias of included trials. We found trends towards reduced all-cause mortality in all SRs (RR 0.91 [95% CI 0.85 to 0.97]), (RR 0.91 [95% CI 0.83 to 1.01]) and (RR 0.78 [95% CI 0.53 to 1.15]) though it was not statistically significant in two SRs. When stratified by baseline risk, the effect on all-cause mortality was no longer statistically significant except in one medium risk category. One review reported significant reductions (RR 0.85 [95% CI 0.77 to 0.95]) in vascular deaths and non-significant reductions in non-vascular deaths (RR 0.97 [95% CI 0.88 to 1.07]). There were significant reductions in composite outcomes overall, but mixed results were reported in these when stratified by baseline risk. These reviews included studies with participants considered risk equivalent to those with established CVD. Conclusions There is limited evidence on the effectiveness of statins for primary prevention with mixed findings from studies including participants with widely ranging baseline risks. Decision making for the use of statins should consider individual baseline risk, absolute risk reduction and whether risk reduction justifies potential harms and taking a daily medicine for life. Trial registration number CRD42017064761.