Table 1.

VTE risk factor classification

ESC2 ISTH1 
RF categoryRecurrence riskExamplesRF categoryRecurrence risk or risk of index eventExamples
VTE provoked by a transient risk factor
Major transient or reversible RF associated with >10-fold increased risk for the index VTE event (compared with patients without the risk factor) Low recurrence risk* (<3%/y) Surgery with GA for >30 min Major transient RF during the 3 mo before diagnosis of VTE Half the risk of recurrent VTE (compared with if there was no transient risk factor), when the risk factor occurred up to 3 mo before the VTE or RF was associated with >10-fold increased risk of having a first VTE Surgery with GA for >30 min 
Confined to bed in hospital (only bathroom privileges) for ≥3 days because of an acute illness or acute exacerbation of a chronic illness Confined to bed in hospital (only bathroom privileges) for ≥3 days because of an acute illness 
Cesarean section 
Trauma with fractures   
Transient or reversible factors associated with ≤10-fold increased risk for (index) VTE or Intermediate recurrence risk (3-8%/y) Minor surgery (GA for <30 min) Minor (yet important) transient RF during the 2 mo before diagnosis of VTE Half the risk of recurrent VTE after stopping anticoagulant therapy (compared with if there was no transient RF), when the RF occurred up to 2 mo before the VTE or RF was associated with a 3- to 10-fold increase in the risk of having a first VTE Surgery with GA for <30 min 
Admission to hospital for <3 days with an acute illness Admission to hospital for <3 days with an acute illness 
Estrogen therapy/contraception Estrogen therapy 
Pregnancy or puerperium  Pregnancy or puerperium 
Confined to bed out of hospital for ≥3 days with an acute illness  Confined to bed out of hospital for ≥3 days with an acute illness 
Leg injury (without fracture) associated with reduced mobility for ≥3 days  Leg injury associated with reduced mobility for at least 3 days 
Long haul flight   
Nonmalignant persistent risk factors Or Inflammatory bowel disease   
Active autoimmune disease   
No identifiable risk factor No identifiable risk factor Unprovoked VTE 
 Recurrence risk individualized/stratified using other assessments† No provoking factors (transient or persistent) 
   VTE provoked by a persistent risk factor 
 High recurrence risk (>8%/y) Active cancer Active cancer  Cancer is considered active if any of the following apply: (1) has not received potentially curative treatment; or (2) there is evidence that treatment has not been curative (eg, recurrent or progressive disease); or (3) treatment is ongoing 
At least 1 previous episode of VTE in the absence of a major transient or reversible factor 
Antiphospholipid antibody syndrome 
 
   Ongoing nonmalignant condition associated with at least a 2-fold risk of recurrent VTE after stopping anticoagulant therapy  Inflammatory bowel disease. 
ESC2 ISTH1 
RF categoryRecurrence riskExamplesRF categoryRecurrence risk or risk of index eventExamples
VTE provoked by a transient risk factor
Major transient or reversible RF associated with >10-fold increased risk for the index VTE event (compared with patients without the risk factor) Low recurrence risk* (<3%/y) Surgery with GA for >30 min Major transient RF during the 3 mo before diagnosis of VTE Half the risk of recurrent VTE (compared with if there was no transient risk factor), when the risk factor occurred up to 3 mo before the VTE or RF was associated with >10-fold increased risk of having a first VTE Surgery with GA for >30 min 
Confined to bed in hospital (only bathroom privileges) for ≥3 days because of an acute illness or acute exacerbation of a chronic illness Confined to bed in hospital (only bathroom privileges) for ≥3 days because of an acute illness 
Cesarean section 
Trauma with fractures   
Transient or reversible factors associated with ≤10-fold increased risk for (index) VTE or Intermediate recurrence risk (3-8%/y) Minor surgery (GA for <30 min) Minor (yet important) transient RF during the 2 mo before diagnosis of VTE Half the risk of recurrent VTE after stopping anticoagulant therapy (compared with if there was no transient RF), when the RF occurred up to 2 mo before the VTE or RF was associated with a 3- to 10-fold increase in the risk of having a first VTE Surgery with GA for <30 min 
Admission to hospital for <3 days with an acute illness Admission to hospital for <3 days with an acute illness 
Estrogen therapy/contraception Estrogen therapy 
Pregnancy or puerperium  Pregnancy or puerperium 
Confined to bed out of hospital for ≥3 days with an acute illness  Confined to bed out of hospital for ≥3 days with an acute illness 
Leg injury (without fracture) associated with reduced mobility for ≥3 days  Leg injury associated with reduced mobility for at least 3 days 
Long haul flight   
Nonmalignant persistent risk factors Or Inflammatory bowel disease   
Active autoimmune disease   
No identifiable risk factor No identifiable risk factor Unprovoked VTE 
 Recurrence risk individualized/stratified using other assessments† No provoking factors (transient or persistent) 
   VTE provoked by a persistent risk factor 
 High recurrence risk (>8%/y) Active cancer Active cancer  Cancer is considered active if any of the following apply: (1) has not received potentially curative treatment; or (2) there is evidence that treatment has not been curative (eg, recurrent or progressive disease); or (3) treatment is ongoing 
At least 1 previous episode of VTE in the absence of a major transient or reversible factor 
Antiphospholipid antibody syndrome 
 
   Ongoing nonmalignant condition associated with at least a 2-fold risk of recurrent VTE after stopping anticoagulant therapy  Inflammatory bowel disease. 

GA, general anesthesia; RF, risk factor.

*

If anticoagulation is discontinued after the first 3 months.

†

Described in text of guideline and in this current review.

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