risk factors and associated increased risk for development of venous thromboembolism in surgical patients

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Risk FactorAssociated Increased Risk
Age

Exponential increase in risk with age in the general population:

< 40 years results in Annual risk 1/10,000

60-69 years results in Annual risk 1/1,000

> 80 years Annual risk 1/100

Obesityif BMI > 30 kg/m^2 then Three times
Previous VTERecurrence rate of 5% per year, increased by surgery
MalignancySeven times
Hormone therapy

HRT results in two-three times

oral contraceptives results in three times

tamoxifen results in three times

high dose progestogens results in six times

raloxifene results in three times

Pregnancyten times increased risk
ImmobilityBed rest > three days, plaster casts and paralysis -> result in ten times
HospitalisationAcute trauma, acute illness and surgery > result in ten times

 

NICE have also outlined patient-related risk factors for venous thromboembolism (VTE). However there is no assessment of degree of increased risk associated with each risk factor.

  • regard surgical patients and patients with trauma as being at increased risk of VTE if they meet one of the following criteria:
    • surgical procedure with a total anaesthetic and surgical time of more than 90 minutes, or 60 minutes if the surgery involves the pelvis or lower limb
    • acute surgical admission with inflammatory or intra-abdominal condition
    • expected significant reduction in mobility
    • one or more of the risk factors shown in Box 1

  • Box 1: Risk factors for VTE
      • Active cancer or cancer treatment
      • Age over 60 years
      • Critical care admission
      • Dehydration
      • Known thrombophilias
        • inherited thrombophilias, for example:
          • High levels of coagulation factors (for example, Factor VIII)
          • Hyperhomocysteinaemia
          • Low activated protein C resistance (for example, Factor V Leiden)
          • Protein C, S and antithrombin deficiencies
          • Prothrombin 2021A gene mutation.
      • Obesity (body mass index [BMI] over 30 kg/m2)
      • One or more significant medical comorbidities (for example: heart disease; metabolic, endocrine or respiratory pathologies; acute infectious diseases; inflammatory conditions)
      • Personal history or first-degree relative with a history of VTE
      • Use of hormone replacement therapy
      • Use of oestrogen-containing contraceptive therapy
      • Varicose veins with phlebitis
      • For women who are pregnant or have given birth within the previous 6 weeks see Box 2

Box 2: Risk factors for VTE in pregnancy or in women who have given birth within the previous 6 weeks

    • consider offering pharmacological VTE prophylaxis with LMWH (or UFH for patients with renal failure) to women who are pregnant or have given birth within the previous 6 weeks who are admitted to hospital but are not undergoing surgery, and who have one or more of the following risk factors:
      • expected to have significantly reduced mobility for 3 or more days
      • active cancer or cancer treatment
      • age over 35 years
      • critical care admission
      • dehydration
      • excess blood loss or blood transfusion
      • known thrombophilias
      • obesity (pre-pregnancy or early pregnancy BMI over 30 kg/m2)
      • one or more significant medical comorbidities (for example: heart disease; metabolic, endocrine or respiratory pathologies; acute infectious diseases; inflammatory conditions)
      • personal history or a first-degree relative with a history of VTE
      • pregnancy-related risk factor (such as ovarian hyperstimulation, hyperemesis gravidarum, multiple pregnancy or pre-eclampsia)
      • varicose veins with phlebitis.
    • consider offering combined VTE prophylaxis with mechanical methods and LMWH (or UFH for patients with renal failure) to women who are pregnant or have given birth within the previous 6 weeks who are undergoing surgery, including caesarean section
    • mechanical and/or pharmacological VTE prophylaxis should be offered to women who are pregnant or have given birth within the previous 6 weeks only after assessing the risks and benefits and discussing these with the woman and with healthcare professionals who have knowledge of the proposed method of VTE prophylaxis during pregnancy and post partum. Plan when to start and stop pharmacological VTE prophylaxis to minimise the risk of bleeding

Reference:

  1. MeReC Bulletin (2003); 13(4):13-16.
  2. NICE (January 2010). Reducing the risk of venous thromboembolism
  3. NICE (April 2007). Venous thromboembolism Reducing the risk of venous thromboembolism (deep vein thrombosis and pulmonary embolism) in inpatients undergoing surgery) .

Last reviewed 08/2020

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