Monday, 17 August 2015

Risk of Blood Clots

Chung WS, Lin CL, Tsai TC, Hsu WH, Kao CH. Multiple Sclerosis Increases the Risk of Venous Thromboembolism: A Nationwide Cohort Analysis. Eur J Clin Invest. 2015. doi: 10.1111/eci.12502. [Epub ahead of print]

OBJECTIVES:The purpose of this study was to evaluate the effects of multiple sclerosis (MS) on the risk of venous thromboembolism (VTE) development.
METHODS:We identified patients diagnosed with MS in Taiwan between 1998 and 2010 by using the National Health Insurance Research Database and the Catastrophic Illness Patient Database (RCIPD). Each MS patient was frequency-matched to 4 controls according to age, sex, and the year of MS registration to the RCIPD. Patients with a history of VTE and incomplete information of age and sex were excluded. All patients were followed up from the index year until VTE diagnosis, loss to follow up, or the end of 2010. We calculated the hazard ratios (HRs) and 95% confidence intervals (CIs) of VTE in the MS and comparison cohorts by using Cox proportional hazards regression models.
RESULTS: We followed up 1238 MS patients and 4952 comparison patients for approximately 6437 and 27 595 person-years, respectively. After adjusting for age, sex, and comorbidities, the MS patients exhibited a 6.87-fold increased risk of VTE compared with the control patients. Women with MS were associated with an 11.1-fold increased risk of VTE development compared with the non-MS women (95% CI: 2.70-45.5). The MS patients aged < 50 years exhibited a 14.8-fold increased risk of developing VTE compared with age-matched patients in the comparison cohort (95% CI: 2.99-73.4). The risk of VTE development increased with the duration of hospitalization stay.
CONCLUSION: MS patients are associated with significantly greater risk of developing VTE compared with non-MS patients.

Venous thromboembolism (VTE) is a condition where a blood clot forms in a vein. This is most common in a leg vein, where it's known as deep vein thrombosis (DVT). A blood clot in the lungs is called pulmonary embolism (PE). If you sit without leg movement it is well known that there is an increased risk of DVT, as occurs with flights. Maybe one of the neuros will give you advice on how to reduce these.


  1. Not sure about this study. Is there an increased risk of VTE per se, just because you have MS or is it related to your level of activity?
    I remain fully mobile, am working, walking the dog, gym & yoga. Have footdrop but that is all in terms of visible problems. Do I have an increased VTE risk just because I have MS?
    It is not clear that this study looked at function. They can't have matched any decreased activity with a control of similar function as I suppose a control with limited mobility would have had a VTE risk as well and there would be too many confounding factors.
    Does this study tell me (us) anything new or useful?

  2. Thanks MD for this post. After seeing this I looked at the NHS Choices webpage on DVT and did the online VTE assessment quiz. It highlighted that due to my autoimmune disease I have increased risk and had advice how to reduce the risk.

  3. I was just coming here to write what Sue A wrote. If this is supposed to be meaningful to people with MS, it fails - it doesn't tell us what we can do to prevent clots. Do we have an inherent risk due to the MS, or is it from being immobile? They should have also compared MS patients to non-ambulatory non-MS patients. Then it would be useful.

    1. Reading the NHS Choices webpage any autoimmune disease is an increased risk of DVT. They also say:

      Who is at risk?

      Each year, 1 in every 1,000 people in the UK is affected by DVT.

      Anyone can develop DVT, but it becomes more common with age. As well as age, risk factors include:

      previous venous thromboembolism
      a family history of blood clots
      medical conditions such as cancer and heart failure
      inactivity – for example, after an operation
      being overweight or obese

      Here's the link to the page that discusses preventing DVT.

  4. I went to the doctor, saw a GP registrar. At the end of the consultation I mentioned my swollen feet and lower legs, she went and got a senior doctor for a second opinion. Within a couple of hours I was in the vascular clinic being checked for DVT. I was okay, but it was only a chance remark that got me checked. Scary eh?


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