Sometimes it’s not over when it’s over

Each week, we select an article from an influential journal that has broad implications for health care and has just become available for free online.

The week’s article reports on a study that ought to get the attention of clinicians in many specialties. Venous thrombosis, a condition in which clots form in veins that can include the large veins in the leg or veins in the lung, is a serious problem when it occurs. It’s treated aggressively with anti-clotting drugs and other measures until the clot dissolved, and patients typically stay on anti-clotting medications for up to a year after the incident.

In the news-you-can-use department, everyone should realize that one well-documented cause of deep venous thrombosis in the legs is sitting still for hours at a time, as people have to do on airplanes. If you see an article in an airline magazine about “exercise” at your seat, take it seriously — a few ankle rolls and the like could spare you a medical adventure you don’t want to have.

In this study, investigators learned that patients face an increased risk of death for at least eight years following the initial attack. The risk is a high as a four-fold increase in patients with cancer, but even in other circumstances the risk of death seems to double for many years.

Does this reflect an underlying problem in the patient? Is it a lasting shock to the system that never quite goes away? The study can’t answer questions like this. The authors also don’t answer the key question — what should patients and clinicians do about this? That will require the ever-popular further study. For now, though, the message seems clear: in venous thrombosis, the clot may go away, but the risk doesn’t.

Check out the abstract below or go right to the free full text.

PubMed Citation

PLoS Med. 2012 Jan;9(1):e1001155. Epub 2012 Jan 10.

Long-term survival in a large cohort of patients with venous thrombosis: incidence and predictors.

Flinterman LE, van Hylckama Vlieg A, Cannegieter SC, Rosendaal FR.


Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands.



Venous thrombosis is a common disease with a high mortality rate shortly after the event. However, details on long-term mortality in these patients are lacking. The aim of this study was to determine long-term mortality in a large cohort of patients with venous thrombosis.


4,947 patients from the Multiple Environmental and Genetic Assessment study of risk factors for venous thrombosis (MEGA study) with a first nonfatal venous thrombosis or pulmonary embolism and 6,154 control individuals without venous thrombosis, aged 18 to 70 years, were followed up for 8 years. Death and causes of death were retrieved from the Dutch death registration. Standardized mortality ratios (SMRs) were calculated for patients compared with control individuals. Several subgroups were studied as well. 736 participants (601 patients and 135 controls) died over a follow-up of 54,948 person-years. The overall mortality rate was 22.7 per 1,000 person-years (95% CI 21.0-24.6) for patients and 4.7 per 1,000 person-years (95% CI 4.0-5.6) for controls. Patients with venous thrombosis had a 4.0-fold (95% CI 3.7-4.3) increased risk of death compared with controls. The risk remained increased up to 8 years after the thrombotic event, even when no additional comorbidities were present. The highest risk of death was found for patients with additional malignancies (SMR 5.5, 95% CI 5.0-6.1). Main causes of death were diseases of the circulatory system, venous thrombosis, and malignancies. Main limitation was a maximum age of 70 at time of inclusion for the first event. Therefore results can not be generalized to those in the highest age categories.


Patients who experienced a first venous thrombosis had an increased risk of death which lasted up to 8 years after the event, even when no comorbidities were present at time of thrombosis. Future long-term clinical follow-up could be beneficial in these patients. Please see later in the article for the Editors’ Summary.

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