Does taking statins prevent blood clots in the veins in people who have not previously had blood clots?

Key messages

– Using statins for the primary prevention of venous thromboembolism (VTE; a condition in which a blood clot or embolism forms in the veins) may slightly reduce the incidence of VTE and mortality from any cause, but the reduction may be too small to be important.

– Statins may not affect your chance of developing deep vein thrombosis (DVT; a blood clot in the lower leg), pulmonary embolism (PE; a blood clot in the lungs), or myopathy (a condition affecting skeletal muscle).

– The available evidence was limited and we are not confident in its reliability. Future prospective studies should be well designed and conducted. They should involve a large number of people and should be carried out over a reasonable period of time of at least a year.

What is venous thromboembolism (VTE)?

VTE is a condition in which a blood clot (embolism) forms in the veins. Blood flow through the affected vein is reduced by the clot, causing swelling and pain. VTE most often occurs in the “deep veins” of the legs, thighs, or pelvis and is called DVT. If a blood clot breaks off and travels to the lungs, it is called PE. Every year, out of 100,000 people worldwide, 57 are diagnosed with VTE, 35 with DVT and 21 with PE.

Statins, which include atorvastatin, fluvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin and simvastatin, are the most commonly used cholesterol-lowering drugs. These statins potentially lower cholesterol levels and therefore may reduce the incidence of VTE.

What did we want to know?

We aimed to clarify the benefits and risks of statins for the primary prevention of VTE (first diagnosis) in individuals who have not previously had VTE.

What have we done?

We searched for randomized controlled trials (RCTs) comparing the use of statins with placebo (i.e. counterfeit or “dummy” pills) or usual care (usual care, such as changing diet) to assess whether statins have an effect on the number of people who developed new VTE or experienced any side effects.

RCTs are experimental studies in which participants are randomly assigned to two or more treatment groups. This random method of assigning people to groups helps reduce the risk of bias by ensuring that the groups are similar and that neither the researchers nor the participants know who is in which group.

What did we find?

Our review covered 27 RCTs involving 122,601 adults (over 18 years of age); two studies focused on participants over 60 years of age. Although one study involved a healthy population, participants in the remaining 26 studies suffered from various diseases. All studies included both men and women. Two studies included participants from primary health care centers and the remaining 25 from hospitals.

Statins included atorvastatin, rosuvastatin, pravastatin, lovastatin, fluvastatin and simvastatin. Most studies (23 of 27) followed participants for more than a year. Similarly, the majority of studies (24 out of 27) received funding from commercial companies.

We pooled the results of individual studies and found that statins may slightly reduce the incidence of VTE. The number of VTE cases prevented by statins was small. However, statins cannot reduce the number of blood clots in the legs or lungs, defined as DVT and PE, respectively. We found no evidence of a difference in the incidence of less severe side effects such as myopathy. There is a possibility that statins may reduce the incidence of death from any cause or serious side effects.

What are the limitations of the evidence?

We are not very confident in the results due to concerns about the methods used in some of the studies. The low number of blood clots makes it difficult to detect effects. Differences in the overall health of participants and in the dosage and types of statins used in studies further complicate the task. Exclusion of studies that did not report the incidence of VTE may mean that relevant studies were missed, which could have influenced the conclusions of this review.

How relevant is this evidence?

Evidence valid as of March 13, 2023.