Statins for the primary prevention of venous thromboembolism.

Background: Venous thromboembolism (VTE) involves the formation of a blood clot in a vein, and includes deep venous thrombosis (DVT) or pulmonary embolism (PE). The annual incidence for VTE varies from 0.75 to 2.69 per 1000 individuals, with about 40 million people worldwide impacted by VTE. Statins, 3-hydroxy-3-methylglutaryl (HMG)-coenzyme A (CoA) reductase inhibitors, inhibit cholesterol biosynthesis and display several vascular-protective effects, including antithrombotic properties. However, the potential role of statins in the primary prevention of VTE is still not clear.

Objectives: To evaluate the benefits and risks of statins in preventing venous thromboembolism (VTE) in individuals with no prior history of VTE.

Search methods: We used standard Cochrane search methods. The search was last updated on 13 March 2023.

Selection criteria: We included randomized controlled trials (RCTs) comparing statins with any control intervention (including placebo and usual care) in healthy individuals or participants with conditions other than VTE. There were no restrictions on the dose, duration, route, or timing of statins.

Data collection and analysis: We used standard Cochrane methods. Our primary outcomes were VTE, DVT, and PE. Our secondary outcomes were serious adverse events, adverse events, and mortality. We used the trial sequential analysis (TSA) method to judge whether the evidence was sufficient, and we used the GRADE approach to assess the certainty of the evidence for each outcome.

Main results: We included 27 RCTs involving 122,601 adults (aged 18 years and above) who were healthy, had various medical conditions (e.g. hypercholesterolemia), or were at risk for cardiovascular disease. Both males and females were included in all studies. Two studies focused solely on participants over 60 years of age. We deemed four studies to have a low risk of bias overall, while 19 were at high risk of bias, and four were unclear. The 27 studies compared use of statins versus placebo or usual care in individuals who had never experienced VTE. The statins used in the studies were atorvastatin, rosuvastatin, pravastatin, lovastatin, fluvastatin, and simvastatin. Twenty-three studies followed up participants for over a year, with six of those extending follow-ups for over five years. Twenty-five studies were based in hospitals, and 24 studies were funded by industry. Only one study used VTE as a primary endpoint. The median incidence of VTE in the statins group was 0.72% (ranging from 0% to 10.53%), and in the control group it was 0.89% (ranging from 0% to 6.83%). Our pooled analysis of the 27 studies showed that, relative to control groups, statins may slightly reduce the overall incidence of VTE (odds ratio (OR) 0.86, 95% confidence intervals (CI) 0.76 to 0.98; 27 studies, 122,601 participants; low-certainty evidence). Of the statins we evaluated, only rosuvastatin seemed to be associated with a reduced incidence of VTE, albeit the reduction in incidence was very small. The evidence did not clearly indicate a difference between groups in the incidence of DVT (OR 0.70, 95% CI 0.41 to 1.18; six studies, 40,305 participants; low-certainty evidence), PE (OR 0.83, 95% CI 0.46 to 1.52; five studies, 28,427 participants; low-certainty evidence), or myopathy (OR 1.10, 95% CI 0.83 to 1.45; 10 studies, 75,551 participants; low-certainty evidence). Nonetheless, statin use might slightly decrease the incidence of any serious adverse event (OR 0.95, 95% CI 0.91 to 0.99; 13 studies, 67,020 participants; low-certainty evidence) and any death (OR 0.90, 95% CI 0.86 to 0.95; 24 studies, 116,761 participants; low-certainty evidence), compared to control.

Authors' conclusions: Using statins for the primary prevention of VTE may slightly reduce the incidence of VTE and all-cause mortality. However, this effect is likely too weak to be considered significant. Statin use may not decrease the occurrence of DVT and PE. The current evidence is insufficient to draw strong conclusions because of the risk of bias in the studies, imprecision in the effect estimates, and potential publication bias. More evidence from well conducted and fully reported RCTs is needed to assess the preventive effects of different types of statins, as well as the effects of different dosages and treatment durations in various populations.