Effect of statins on venous thromboembolic events: a meta-analysis of published and unpublished evidence from randomised controlled trials

Venous thrombosis and cancer: from mouse models to clinical trials

Cancer patients have a ~4 fold increased risk of venous thromboembolism (VTE) compared with the general population and this is associated with significant morbidity and mortality. This review summarizes our current knowledge of VTE and cancer, from mouse models to clinical studies. Notably, the risk of VTE varies depending on the type and stage of cancer. For instance, pancreatic and brain cancer patients have a higher risk of VTE than breast and prostate cancer patients. Moreover, patients with metastatic disease have a higher risk than those with localized tumors. Tumor-derived procoagulant factors and growth factors may directly and indirectly enhance VTE. For example, increased levels of circulating tumor-derived, tissue factor-positive microvesicles may trigger VTE. In a mouse model of ovarian cancer, tumor-derived IL-6 and hepatic thrombopoietin have been linked to increased platelet production and thrombosis. In addition, mouse models of mammary and lung cancer showed that tumor-derived granulocyte colony-stimulating factor causes neutrophilia and activation of neutrophils. Activated neutrophils can release neutrophil extracellular traps (NETs) that enhance thrombosis. Cell-free DNA in the blood derived from cancer cells, NETs and treatment with cytotoxic drugs can activate the clotting cascade. These studies suggest that there are multiple mechanisms for VTE in patients with different types of cancer. Preventing and treating VTE in cancer patients is challenging; the current recommendations are to use low-molecular-weight heparin. Understanding the underlying mechanisms may allow the development of new therapies to safely prevent VTE in cancer patients.

Venous thrombosis

Venous thromboembolism (VTE) encompasses deep-vein thrombosis (DVT) and pulmonary embolism. VTE is the leading cause of lost disability-adjusted life years and the third leading cause of cardiovascular death in the world. DVT leads to post-thrombotic syndrome, whereas pulmonary embolism can cause chronic pulmonary hypertension, both of which reduce quality of life. Genetic and acquired risk factors for thrombosis include non-O blood groups, factor V Leiden mutation, oral contraceptive use, hormone replacement therapy, advanced age, surgery, hospitalization and long-haul travel. A combination of blood stasis, plasma hypercoagulability and endothelial dysfunction is thought to trigger thrombosis, which starts most often in the valve pockets of large veins. Animal studies have revealed pathogenic roles for leukocytes, platelets, tissue factor-positive microvesicles, neutrophil extracellular traps and factors XI and XII. Diagnosis of VTE requires testing and exclusion of other pathologies, and typically involves laboratory measures (such as D-dimer) and diagnostic imaging. VTE is treated with anticoagulants and occasionally with thrombolytics to prevent thrombus extension and to reduce thrombus size. Anticoagulants are also used to reduce recurrence. New therapies with improved safety profiles are needed to prevent and treat venous thrombosis. For an illustrated summary of this Primer, visit: http://go.nature.com/8ZyCuY.

Concurrent use of statins and hormone therapy and risk of venous thromboembolism in postmenopausal women: a population-based case-control study

OBJECTIVE

Statins and hormone therapy (HT), often used concurrently in postmenopausal women, have antagonist effects on the risk of venous thromboembolism (VTE). This study aims to determine whether statins attenuate the increased VTE risk associated with HT.

METHODS

We conducted a nested case-control study within a population-based cohort of women aged 50 to 79 years between January 1, 1987 and March 1, 2008, who were identified from the UK General Practice Research Database. Cases of VTE occurring during follow-up were identified and each matched with up to 10 controls from the cohort. Odds ratios (ORs) for the effects of concurrent HT and statin use on the risk of VTE were estimated using conditional logistic regression with interaction terms.

RESULTS

The cohort included 955,582 postmenopausal women, with 23,505 cases of VTE matched with 231,562 controls. Regardless of any HT use, current use of statins was associated with a decreased risk of VTE (OR, 0.83; 95% CI, 0.78-0.87). The interaction between statin use and HT use was of borderline significance (P = 0.053). Consequently, among nonusers of statins, the risk of VTE was elevated with current use of oral estrogen and progestogen combinations (OR, 1.55; 95% CI, 1.45-1.66) but this risk was not elevated among users of statins (OR, 0.98; 95% CI, 0.56-1.73). There was no such modification of the OR with statins and other HT types and formulations.

CONCLUSIONS

Statins could potentially attenuate the increased risk associated with HT combinations of oral estrogens and progestogens. This observation needs further confirmation in other large cohorts.

Is lipid lowering therapy an independent risk factor for venous thromboembolism? A population-based case-control study

INTRODUCTION

The independent effect of lipid lowering therapy (LLT) on venous thromboembolism (VTE) risk is uncertain.

OBJECTIVE

To test statin and non-statin LLT as potential VTE risk factors.

METHODS

Using Rochester Epidemiology Project resources, we identified all Olmsted County, MN residents with objectively diagnosed incident VTE (cases) over the 13-year period, 1988-2000 (n=1340), and one to two matched controls (n=1538). We reviewed their complete medical records for baseline characteristics previously identified as independent VTE risk factors, and for statin and non-statin LLT. Using conditional logistic regression, we tested the overall effect of LLT on VTE risk and also separately explored the role of statin versus that of non-statin LLT, adjusting for other baseline characteristics.

RESULTS

Among cases and controls, 74 and 111 received statin LLT, and 32 and 50 received non-statin LLT, respectively. Univariately, and after individually controlling for other potential VTE risk factors (i.e., BMI, trauma/fracture, leg paresis, hospitalization for surgery or medical illness, nursing home residence, active cancer, central venous catheter, varicose veins, prior superficial vein thrombosis, diabetes, congestive heart failure, angina/myocardial infarction, stroke, peripheral vascular disease, smoking, anticoagulation), LLT was associated with decreased odds of VTE (unadjusted OR=0.73; p=0.03). When considered separately, statin and non-statin LLT were each associated with moderate, non-significant lower odds of VTE. After adjusting for angina/myocardial infarction, each was significantly associated with decreased odds of VTE (OR=0.63, p<0.01 and OR=0.61, p=0.04, respectively).

CONCLUSIONS

LLT is associated with decreased VTE risk after adjusting for known risk factors.

Statins improve the resolution of established murine venous thrombosis: reductions in thrombus burden and vein wall scarring

Despite anticoagulation therapy, up to one-half of patients with deep vein thrombosis (DVT) will develop the post-thrombotic syndrome (PTS). Improving the long-term outcome of DVT patients at risk for PTS will therefore require new approaches. Here we investigate the effects of statins—lipid-lowering agents with anti-thrombotic and anti-inflammatory properties—in decreasing thrombus burden and decreasing vein wall injury, mediators of PTS, in established murine stasis and non-stasis chemical-induced venous thrombosis (N = 282 mice). Treatment of mice with daily atorvastatin or rosuvastatin significantly reduced stasis venous thrombus burden by 25% without affecting lipid levels, blood coagulation parameters, or blood cell counts. Statin-driven reductions in VT burden (thrombus mass for stasis thrombi, intravital microscopy thrombus area for non-stasis thrombi) compared similarly to the therapeutic anticoagulant effects of low molecular weight heparin. Blood from statin-treated mice showed significant reductions in platelet aggregation and clot stability. Statins additionally reduced thrombus plasminogen activator inhibitor-1 (PAI-1), tissue factor, neutrophils, myeloperoxidase, neutrophil extracellular traps (NETs), and macrophages, and these effects were most notable in the earlier timepoints after DVT formation. In addition, statins reduced DVT-induced vein wall scarring by 50% durably up to day 21 in stasis VT, as shown by polarized light microscopy of picrosirius red-stained vein wall collagen. The overall results demonstrate that statins improve VT resolution via profibrinolytic, anticoagulant, antiplatelet, and anti-vein wall scarring effects. Statins may therefore offer a new pharmacotherapeutic approach to improve DVT resolution and to reduce the post-thrombotic syndrome, particularly in subjects who are ineligible for anticoagulation therapy.

Statins, aspirin and risk of venous thromboembolic events in breast cancer patients

Venous thromboembolic events (VTE's) are associated with decreased survival in breast cancer patients. Studies suggested that statins reduce the risk of VTE's in the general population. Low dose Aspirin reduces risk of VTE's in high risk populations. The Breast Cancer in Northern Israel Study is a case-control study of consecutive breast cancer cases diagnosed in northern Israel and matched controls. The present analysis was limited to cases with breast cancer enrolled in the study. Data was extracted from Clalit Health Services (CHS) database and from computerized pharmacy records. Out of 3,585 patients enrolled, 261 (7.3%) had a VTE during median follow up of 4.2 years. The 1 and 2 year cumulative incidence was 2.64 and 3.65%. 55.7% of patients used statins, predominantly simvastatin (75.8%). 44.5% used aspirin. In multivariate analysis neither statins nor aspirin use was associated with a reduced risk for a VTE. Unadjusted HR for statin and aspirin was 1.461 (1.018-2.096) and 1.293 (0.846-1.976), respectively, and the adjusted HR were 0.86 (0.648-1.14) and 1.013 (0.737-1.392). Results were similar when only simvastatin use was assessed. Metastatic disease, chemotherapy, age, BMI and presence of comorbidities were significantly associated with risk of VTE's. Our study is the first to look at the effect of statins and aspirin on the incidence of VTE's in patients with breast cancer. In our cohort, statin and aspirin use did not decrease the risk for a VTE. Our results might be explained by use of low potency statins (simvastatin and pravastatin) and by alternate mechanisms for VTE formation in patients with cancer.

Statins for primary prevention of venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE) is common in clinical practice. The efficacy of statins in the primary prevention of VTE remains unproven. This is an update of the review first published in 2011.

OBJECTIVES

To assess the efficacy of statins in the primary prevention of VTE.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases (PVD) Group Trials Search Co-ordinator searched the Specialised Register (last searched February 2014) and CENTRAL (2014, Issue 1).

SELECTION CRITERIA

Randomised controlled trials (RCTs) that assessed statins in the primary prevention of VTE were considered. The outcomes we evaluated were the rates of VTE, cardiovascular and cerebrovascular events, death and adverse events. Two authors (L Li, JH Tian) independently selected RCTs against the inclusion criteria. Disagreements were resolved by discussion with a third author (KH Yang).

DATA COLLECTION AND ANALYSIS

Data extraction was independently carried out by two authors (L Li, JH Tian). Disagreements were resolved by discussion with a third author (PZ Zhang). Two authors (L Li, JH Tian) independently assessed the risk of bias according to a standard quality checklist provided by the PVD Group.

MAIN RESULTS

For this update we included one RCT with 17,802 participants that assessed rosuvastatin compared with placebo for the prevention of VTE. The quality of the evidence was moderate because of imprecision, as the required sample size for the outcomes of this review was not achieved. Analysis showed that when compared with placebo rosuvastatin reduced the incidence of VTE (odds ratio (OR) 0.57, 95% confidence interval (CI) 0.37 to 0.86) and deep vein thrombosis (DVT) (OR 0.45, 95% CI 0.25 to 0.79), the risk of any (fatal and non-fatal) myocardial infarction (MI) (OR 0.45, 95% CI 0.30 to 0.69), and any (fatal and non-fatal) stroke (OR 0.51, 95% CI 0.34 to 0.78). There was no difference in the incidence of pulmonary embolism (PE) (OR 0.77, 95% CI 0.41 to 1.46), fatal MI (OR 1.50, 95% CI 0.53 to 4.22), fatal stroke (OR 0.30, 95% CI 0.08 to 1.09) or death after VTE (OR 0.50, 95% CI 0.20 to 1.24). The incidence of any serious adverse events was no different between the rosuvastatin and placebo groups (OR 1.07, 95% CI 0.95 to 1.20).

AUTHORS' CONCLUSIONS

Available evidence showed that rosuvastatin was associated with a reduced incidence of VTE, but the evidence was limited to a single RCT and any firm conclusions and suggestions could be not drawn. Randomised controlled trials of statins (including rosuvastatin) are needed to evaluate their efficacy in the prevention of VTE.

Influence of statin use on the incidence of recurrent venous thromboembolism and major bleeding in patients receiving rivaroxaban or standard anticoagulant therapy

Background

Statins may reduce the risk of first and recurrent venous thromboembolism (VTE). No data are available on their potential benefit in patients treated with the oral anticoagulant rivaroxaban.

Methods

The EINSTEIN DVT/PE and EINSTEIN Extension studies compared rivaroxaban with standard of care (n=8280) and placebo (n=1188), respectively. The incidences of recurrent VTE and major bleeding per 100 patient-years for exposure (or not) to statins were calculated. A Cox proportional hazards model was constructed, stratified by index event and intended treatment duration, with statin use as a time-dependent variable, for each treatment group (rivaroxaban vs enoxaparin/vitamin K antagonist or placebo) and adjusted for relevant variables.

Results

In EINSTEIN DVT/PE, 1509 (18.3%) patients used statins during the at-risk period, and 6731 (81.7%) did not. Overall, 2.6 recurrent VTEs occurred per 100 patient-years with statin use compared with 3.8 per 100 patient-years without statins (adjusted hazard ratio [HR] 0.76; 95% confidence interval [CI] 0.46–1.25). HRs for recurrent VTE were similar for concomitant use of rivaroxaban-statin and enoxaparin/VKA-statin. Major bleeding events occurred in 3.0 per 100 patient-years with statin use compared with 2.3 per 100 patient-years without statins (adjusted HR 0.77; 95% CI 0.46–1.29). Due to adjustments in the Cox regression model, the direction of this HR is in contrast to the crude comparison. In EINSTEIN Extension, no recurrent VTEs occurred with statin use in the rivaroxaban group compared with 1.6 per 100 patient-years without statins. In the placebo group, 12.2 recurrent VTEs occurred per 100 patient-years with statin use compared with 13.2 per 100 patient-years without (adjusted HR 0.81; 95% CI 0.35–1.86).

Conclusions

The effect of statins in this secondary analysis of the EINSTEIN VTE treatment program is consistent with other studies that suggest a reduced risk of recurrent VTE, but conclusive evidence of this benefit is lacking. Statins are simple to use, inexpensive, very safe and do not cause bleeding. Therefore, the potential effect on reducing recurrent VTE, which is in the range of that of acetylsalicylic acid, deserves evaluation in a large randomized trial.

Trial registration number

ClinicalTrials.gov: EINSTEIN PE, NCT00439777; EINSTEIN DVT, NCT00440193; EINSTEIN Extension, NCT00439725.

The association of statin use with reduced incidence of venous thromboembolism: a population-based cohort study

OBJECTIVES

Venous thromboembolism (VTE) continues to be a frequent medical emergency requiring rapid recognition so as to reach diagnosis and initiate anticoagulation therapy. The use of statins in addition to reducing the incidence of arterial thrombosis for decreasing the incidence and reoccurrence of VTE is reported. The aim of our study was to explore the association between statin usage and the incidence of new VTE at the population level during a 10-year follow-up.

DESIGN

Population-based historic cohort.

SETTING

The Health 2000 Survey was based on a nationally representative sample.

PARTICIPANTS

8028 individuals aged 30 years or over in Finland.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary end point event was the first ever hospitalisation due to one of the following causes: pulmonary embolism (International Classification of Diseases-10 I26), cerebral venous non-pyogenic thrombosis (I63.6), or venous thrombosis (I80.9-189).

RESULTS

The preselected explanatory variables applied to the Poisson regression model were statin usage (no/yes) during follow-up (2000-2011) and several baseline data (age, sex; usage of blood glucose lowering drugs, vitamin K antagonists and antiplatelet agents). We observed 136 VTE events, the incidence of 1.72 (95% CI 1.44 to 2.04) per 1000 person-years. Current statin usage did not associate with the incidence of VTE according to the univariate model (rate ratio (RR) 0.93, 0.56 to 1.52), but when adjusted with baseline variables (age, sex, medications) the RR declined to 0.60 (0.36 to 1.00, p=0.04).

CONCLUSIONS

Statin use offers protection against first ever VTE events and appears as a primary prevention tool in patients without anticoagulation or antiplatelet medication.

Statins are associated with low risk of venous thromboembolism in patients with cancer: a prospective and observational cohort study

INTRODUCTION

Patients with cancer are at risk of venous thromboembolism (VTE). Statin-use has been shown to be associated with low risk of VTE in patients without cancer, but data in cancer patients is scarce. The objective of this study was to evaluate the association of statins with risk of VTE in cancer patients in a prospective observational cohort study.

MATERIALS AND METHODS

Patients with newly diagnosed cancer or progression of disease after remission were included and prospectively followed for a maximum of 2 years. Study endpoint was occurrence of symptomatic VTE.

RESULTS

Patients (n=1434) were followed over a median observation period of 729 days. VTE occurred in 107 (7.5%) patients. At study inclusion, 170 (11.9%) patients took statins. Simvastatin (n=96) and atorvastatin (n=48) were the most frequently prescribed statins. VTE occurred in 6 (3.5%) patients with statins. Patients with statins had a lower risk of VTE than patients without (subhazard ratio 0.43, 95% confidence interval 0.19 to 0.98; p=0.04). In competing risk analysis, the cumulative probability of VTE in patients with statins was 2.94% after 12 months and 3.54% after 24 months, compared to 7.13% and 8.13% in the group without statins (Gray's test: p=0.04).

CONCLUSION

This study provides observational evidence for an association between statin use and low risk of VTE in patients with cancer. The role of statins for prevention of cancer-associated VTE needs to be confirmed in randomized, controlled trials.

Statin use and venous thromboembolism recurrence: a combined nationwide cohort and nested case-control study

BACKGROUND

Data on statins' effect on venous thromboembolism (VTE) recurrence are conflicting.

OBJECTIVES

We examined whether statin use was associated with reduced risk of recurrent VTE in a nationwide population-based setting.

PATIENTS/METHODS

Using the Danish National Patient Registry, we identified first-time and recurrent VTEs between 1 July 2004 and 31 December 2012 (n = 27,862). VTE diagnoses were validated by medical record review of a subsample of patients. We ascertained nationwide prescription data and categorized statin use as current (further divided into new and long-term use), former and no use. We identified statin use at baseline (mimicking an intention-to-treat analysis) and in a time-varying manner during follow-up (mimicking per-protocol analysis) and computed hazard ratios (HRs) for recurrent VTE using Cox regression. In a supplementary nested case-control study, we identified statin use at time of VTE recurrence and computed odds ratios as unbiased estimates of the incidence rate ratios (IRRs) using conditional logistic regression. We adjusted for age, sex, year of diagnosis, provoking factors, co-morbidities and co-medications, including time-varying use of aspirin and anticoagulant drugs.

RESULTS

The adjusted HR comparing current use with no use was 0.72 (95% confidence interval [CI], 0.59-0.88) for recurrent VTE, with a stronger effect of high (0.40; 95% CI, 0.21-0.78) vs. low potency statins (0.77; 95% CI, 0.63-0.94). Consistently, the recurrence rate was reduced in both the time-varying analysis (HR=0.64; 95% CI, 0.54-0.77) and nested case-control analysis (IRR=0.55; 95% CI, 0.45-0.67). The effect was largest for recurrent deep venous thrombosis.

CONCLUSIONS

Statin use was associated with reduced VTE recurrence.

Statins decrease thrombin generation in patients with hypercholesterolemia

OBJECTIVE

Statins are cholesterol-lowering agents with antithrombotic effect possibly unrelated to their lipid-lowering properties. Traditional global coagulation tests failed, however, to reveal clinically relevant change after treatment. We therefore sought to investigate whether statins were able to modify thrombin generation in hypercholesterolemia.

METHODS

Fifty-one patients who needed treatment with statins were enrolled in this study. Thrombin generation, assessed as endogenous thrombin potential (the amount of thrombin generated after triggering coagulation with small amount of tissue factor) was measured at pre- and two months post-treatment with statins.

RESULTS

The median (inter-quartile range) level of total cholesterol that was 325 mg/dL (278-405) decreased significantly [211 mg/dL (197-247)] at post-treatment (p<0.001); the median level of HDL cholesterol that was 49 mg/dL (43-56) increased significantly [55 mg/dL (47-66)] at post-treatment (p<0.001). The median endogenous thrombin potential (inter-quartile range) before treatment was 2372 nM·min (2008-2617) and decreased to 2,048 nM·min (1764-2375) (p<0.001) after treatment.

CONCLUSION

The results support the hypothesis of a direct link between statins and coagulation through their capacity to lower thrombin generation in patients with hypercholesterolemia.

PRACTICE IMPLICATIONS

The antithrombotic properties of statins could be mediated (at least in part) by their endogenous thrombin potential lowering effect. This interesting hypothesis warrants evaluation by clinical trials.

Acute right ventricular failure caused by concomitant coronary and pulmonary embolism: successful treatment with endovascular coronary and pulmonary thrombectomy

Patent foramen ovale (PFO) is present in approximately 25% of the general population. PFO is characterized by intermittent shunting of blood from the right to the left atrium, especially in the context of increased right-sided filling pressures, with risk of paradoxical embolism. We describe a 69-year-old woman presenting with acute chest pain, severe dyspnoea, and acute inferolateral ST-segment elevation on the electrocardiogram. The patient was diagnosed with myocardial infarction and failure of the right cardiac ventricle, which was considered to be secondary to extensive pulmonary embolism leading to increased filling pressures and paradoxical coronary embolism. The patient underwent emergent percutaneous interventions with coronary thrombus extraction and pulmonary thrombus fragmentation and local thrombolysis. The patient was free of symptoms at follow up 6 months later and echocardiography showed substantially improved right ventricular function. We discuss issues related to the diagnosis, treatment, and secondary prevention for patients with concomitant pulmonary and coronary arterial thrombosis.

Unintended effects of statins from observational studies in the general population: systematic review and meta-analysis

BACKGROUND

Efficacy of statins has been extensively studied, with much less information reported on their unintended effects. Evidence from randomized controlled trials (RCTs) on unintended effects is often insufficient to support hypotheses generated from observational studies. We aimed to systematically assess unintended effects of statins from observational studies in general populations with comparison of the findings where possible with those derived from randomized trials.

METHODS

Medline (1998 to January 2012, week 3) and Embase (1998 to 2012, week 6) were searched using the standard BMJ Cohort studies filter. The search was supplemented with reference lists of all identified studies and contact with experts in the field. We included prospective studies with a sample size larger than 1,000 participants, case control (of any size) and routine health service linkage studies of over at least one year duration. Studies in subgroups of patients or follow-up of patient case series were excluded, as well as hospital-based cohort studies.

RESULTS

Ninety studies were identified, reporting on 48 different unintended effects. Statins were associated with lower risks of dementia and cognitive impairment, venous thrombo-embolism, fractures and pneumonia, but these findings were attenuated in analyses restricted to higher quality studies (respectively: OR 0.74 (95% CI 0.62 to 0.87); OR 0.92 (95% CI 0.81 to 1.03); OR 0.97 (95% CI 0.88 to 1.05); OR 0.92 (95% CI 0.83 to 1.02)); and marked heterogeneity of effects across studies remained. Statin use was not related to any increased risk of depression, common eye diseases, renal disorders or arthritis. There was evidence of an increased risk of myopathy, raised liver enzymes and diabetes (respectively: OR 2.63 (95% CI 1.50 to 4.61); OR 1.54 (95% CI 1.47 to 1.62); OR 1.31 (95% CI 0.99 to 1.73)).

CONCLUSIONS

Our systematic review and meta-analyses indicate that high quality observational data can provide relevant evidence on unintended effects of statins to add to the evidence from RCTs. The absolute excess risk of the observed harmful unintended effects of statins is very small compared to the beneficial effects of statins on major cardiovascular events.

Statins, aspirin and risk of thromboembolic events in ovarian cancer patients

OBJECTIVES

Studies suggest that statins and low dose aspirin reduce risk of VTEs in the general population. We aimed to study the effect of these drugs on the incidence of VTEs in patients with ovarian cancer.

METHODS

Patients diagnosed with ovarian cancer between 2000 and 2011 were identified through the Clalit Health Services (CHS) chronic disease registry. Data were extracted from CHS database and from computerized pharmacy records. Use of medications was analyzed as a time dependent covariate in a Cox regression model.

RESULTS

Of 1746 patients 175 (10%) had a VTE during a median follow up of 3.13 years. 83 patients (5.6%) had a VTE within 2 years of diagnosis of ovarian cancer. Use of chemotherapy and stage 3 and 4 at presentation were associated with an increased risk for VTEs. Statins were used by 43.5% of the patients, and 32.3% used aspirin. Aspirin use was associated with a marginally significant reduction in incidence of VTEs within 2 years of diagnosis, HR 0.423 (95% CI 0.182-1.012, p-value 0.053). Statin use was not associated with risk of VTEs.

CONCLUSION

This is the first study looking at the effect of statins and aspirin on the incidence of VTEs in ovarian cancer patients. In our cohort, statins did not decrease the risk for a VTE and aspirin use was associated with a reduced risk which was marginally significant. Our results might be explained by use of low potency statins and by alternate mechanisms for VTE formation in cancer patients.

Clinical evidence of statin therapy in non-dyslipidemic disorders

The clinical benefits of statins are strongly related to their low density lipoprotein cholesterol (LDL-C) lowering properties. However, considering that the pharmacological target of statins, the 3-hydroxy-3-methyl-3-glutaryl coenzyme A (HMG-CoA) reductase, is one of the upstream enzyme of the mevalonate pathway, its inhibition may determine a substantial impoverishment of additional lipid moieties required for a proper cellular function. From this hypothesis, several experimental and clinical evidences have been reported indicating additional effects of statins beyond the LDL-C lowering, in particular anti-inflammatory and immunomodulatory effects. Thus statin therapy, indicated for hyperlipidemic patients for primary and secondary prevention of coronary heart disease (CHD) has begun to be considered effective in other diseases not necessarily linked to altered lipid profile. In the present review we summarized the current clinical evidence of the efficacy and safety profile of statins in a variety of diseases, such as rheumatoid arthritis, venous thromboembolism, liver diseases, polycystic ovary syndrome, and age-related macular degeneration. As discussed in the review, pending large, well designed, randomized trials, it is reasonable to conclude that there is no definitive evidence for the use of statins in the aforementioned diseases.

Anticoagulant effects of statins and their clinical implications

There is evidence indicating that statins (3-hydroxy-methylglutaryl coenzyme A reductase inhibitors) may produce several cholesterol-independent antithrombotic effects. In this review, we provide an update on the current understanding of the interactions between statins and blood coagulation and their potential relevance to the prevention of venous thromboembolism (VTE). Anticoagulant properties of statins reported in experimental and clinical studies involve decreased tissue factor expression resulting in reduced thrombin generation and attenuation of pro-coagulant reactions catalysed by thrombin, such as fibrinogen cleavage, factor V and factor XIII activation, as well as enhanced endothelial thrombomodulin expression, resulting in increased protein C activation and factor Va inactivation. Observational studies and one randomized trial have shown reduced VTE risk in subjects receiving statins, although their findings still generate much controversy and suggest that the most potent statin rosuvastatin exerts the largest effect.

Statin treatment and risk of recurrent venous thromboembolism: a nationwide cohort study

OBJECTIVES

Statins may decrease the risk of primary venous thromboembolism (VTE), that is, deep vein thrombosis (DVT) and pulmonary embolism (PE) but the effect of statins in preventing recurrent VTE is less clear. The aim of this study was therefore to investigate the association between statin therapy and risk of recurrent VTE.

DESIGN

A prospective cohort study.

SETTING

All hospitals in Denmark.

PARTICIPANTS

All patients with a hospital diagnosis of VTE in Denmark during 1997-2009 associated with a warfarin or heparin prescription were identified.

MAIN OUTCOME MEASURES

Adjusted HR of recurrent hospitalised VTE (ie, fatal or non-fatal DVT or PE) associated with use of statins.

RESULTS

44 330 patients with VTE were included in the study. Of these 3914 were receiving statin therapy at baseline. Patients receiving statins were older (68±11 compared to 62±18 years), had more comorbidity and used more medications. The incidence rate for recurrent VTE was 24.4 (95% CI 22.8 to 26.2) per 1000 person-years among statin users and 48.5 (95% CI 47.4 to 49.7) per 1000 person-years among non-statin users. Statin use was associated with a significantly lower risk of a recurrent VTE, adjusted HR 0.74 (95% CI 0.68 to 0.80), compared with no statin use. The association between statin use and risk of recurrent VTE was significantly affected by age. Among younger individuals (≤80 years), statin use was associated with lower risk of recurrent VTE, HR 0.70 (95% CI 0.65 to 0.76) whereas in older individuals (>80 years) statin use was significantly associated with higher risk of recurrent VTE, HR 1.28 (95% CI 1.02 to 1.60), p for interaction=<0.0001.

CONCLUSIONS

Statin use was associated with a decreased risk of recurrent VTE.

Atorvastatin favorably modulates proinflammatory cytokine profile in patients following deep vein thrombosis

BACKGROUND

Venous thromboembolism (VTE) has been shown to be associated with inflammation. Statins that might reduce VTE risk have been found to exert anti-inflammatory properties in patients at cardiovascular risk. We sought to investigate whether anti-inflammatory effects of atorvastatin can be observed in VTE patients.

MATERIALS AND METHODS

Atorvastatin 40 mg/d was given for 3 days to 26 consecutive VTE patients following discontinuation of anticoagulant therapy and 25 controls. We evaluated interleukin (IL)-1b, IL-6, IL-8, IL-10, soluble P-selectin and von Willebrand factor (vWF) antigen in peripheral venous blood.

RESULTS

The VTE patients displayed higher C-reactive protein (p=0.013), IL-1b (p=0.03), IL-8 (p=0.03) and vWF (p<0.0001) compared with the controls. In VTE patients atorvastatin decreased IL-6 (p=0.0003), IL-8 (p=0.003) and P-selectin (p<0.0001), but increased IL-10 (p=0.001), with no association with C-reactive protein or cholesterol-lowering effects. Atorvastatin reduced IL-1b (p=0.01), IL-6 (p=0.03) and P-selectin (p=0.002) in controls. Residual venous thrombosis was associated with elevated IL-6 and P-selectin, whereas patients with proximal deep vein thrombosis showed elevated P-selecitn prior to and following statin administration (all p<0.05).

CONCLUSION

A 3-day administration of atorvastatin reduces inflammation without decrease in C-reactive protein in VTE patients.

Statins and venous thrombosis: a story too good to be true?

Frits Rosendaal comments on new findings from a meta-analysis conducted by Kazem Rahimi and colleagues, evaluating whether statins can prevent venous thromboembolism.