D Dimer: When to Do? How to interpret?

• D Dimer may be measured on day 5/6 of covid-19 in All admitted/ Sick patients being managed at home Mild covid in presence of thrombotic risk factors: Long standing type 2 diabetes, heart disease, stroke, obesity, cancer, immobility, previous history of arterial/venous thrombosis, age> 60 years
• 2 to 3 times elevated D dimer is usually considered significant. The risk factors for thrombosis matter more than absolute D dimer value. Hence D Dimer value should be seen in that context.
• Rising values of D Dimer may have more significance than one single high value. Also, D Dimer may stay elevated for very long after the recovery, so it’s long term implication is not known

Practical aspects of anticoagulation in non-hospital setting in Covid-19

Based on latest evidence ( showing benefit of therapeutic anticoagulation in 2200 moderate Covid pts. in Multi Platform RCT) as well as anticipated need in Indian context based on risk benefit analysis

• Triaging of thrombo-inflammatory risk in Covid-19 may be done on the basis of
  • Severity of Covid-19 pneumonia- mild, moderate, severe ( AIIMS criteria)
  
  
  • Pre-existent thrombotic risk factors: see above
  
  
  • D Dimer values ( > 2-3 times ref. value) : least important. Extremely elevated values ( for e.g. > 2590) in sick patients should prompt a CTPA/enhanced vigilance
  
  
• The risk of venous thromboembolism/PTE among admitted patients is 12 % in non ICU and double in the ICU setting. So the risk in sick patients at home is at least 12 %


• Acute arterial thrombosis, including coronary, may be a cause of many sudden deaths.


• For mild covid , with no thrombotic risk factors, no D-Dimer testing and no anticoagulation is required. This group is at least 80 percent of all covid! (Trials are going on with NOAC and antiplatelets in people in outpatients/post-discharge settings with thrombotic risk factors and/or raised D Dimer. Duration of treatment 3 to 6 weeks.)


• There is a genuine concern of dealyed sudden death in apparently mild Covid. Those who have mild covid and have thrombotic risk factors plus raised D Dimers should be offered half dose anticoagulation ( rivaroxaban 10 mg od/apixaban 2.5 mg bid/ dabigatran 110/75 mg bid) for 3-6 weeks. If they have CAD/stroke, then continue aspirin/clopidogrel as well


• For mild covid with thrombotic risk factors but no elevated D Dimer , antiplatelets may be given for duration of 3-4 weeks. In presence of multiple risk factors ( for e.g age> 60/ or DM+ CAD), low dose anticoagulation as above may be offered


• Patients being managed at home with moderate covid ( SpO2 < 94%/need for high flow O2/ prolonged fever with markedly raised CRP etc) should be given anticoagulation. This may be in form of NOACs or parentral enoxaparin. The dose can be full therapeutic in presence of thrombotic risk factors (with/without raised D Dimer) or low dose/ intermediate dose in case of absence of these risk factors. Bleeding risk is < 2%


• In admitted moderate Covid patients, full dose anticoagulation preferably with heparin/LMWH should be given ( Multi-platform trials)


• In sick ICU patients, only low dose or prophylactic dose anticoagulation is useful


• Sick patients managed at home/hospital may be given extended low dose anticoagulation for 5-6 weeks once they improve.