The Food and Drug Administration (FDA) has developed grading scales for reactions to vaccines during clinical trials. One of these scales deals with coagulopathy.
Patient selection: coagulopathy reaction after the vaccination
Coagulation parameters affected may include:
(1) platelet count per µL
(2) prothrombin time (PT) in seconds relative to the upper limit of normal (ULN)
(3) activated partial thromboplastin time (aPTT) in seconds relative to the upper limit of normal (ULN)
(4) fibrinogen change in mg/dL
|
Reaction |
Grade |
|
none |
0 |
|
mild |
1 |
|
moderate |
2 |
|
severe |
3 |
|
potentially life threatening |
4 |
|
Coagulation Parameter |
Finding |
Grade |
|
platelet count per µL |
125,000 to 140,000 |
1 |
|
|
100,000 to 124,999 |
2 |
|
|
25,000 to 99,9999 |
3 |
|
|
< 25,000 |
4 |
|
PT |
1.01 to 1.10 times ULN |
1 |
|
|
1.11 to 1.20 times ULN |
2 |
|
|
1.21 to 1.25 times ULN |
3 |
|
|
> 1.25 times ULN |
4 |
|
aPTT |
1.01 to 1.10 times ULN |
1 |
|
|
1.11 to 1.20 times ULN |
2 |
|
|
1.21 to 1.25 times ULN |
3 |
|
|
> 1.25 times ULN |
4 |
|
fibrinogen |
> 600 mg/dL |
3 |
|
|
501 to 600 mg/dL |
2 |
|
|
400 to 500 mg/dL |
1 |
|
|
150 to 120 mg/dL |
1 |
|
|
125 to 149 mg/dL |
2 |
|
|
100 to 124 mg/dL |
3 |
|
|
< 100 mg/dL |
4 |
|
|
gross bleeding |
4 |
|
|
DIC |
4 |
where:
• The grade assignment for PT and aPTT probably need adjustment.
• A patient with thrombocytosis can have a significant drop in the platelet count and be in the normal range. The same is true for hyperfibrinogenemia.
Specialty: Infectious Diseases, Pharmacology, clinical
