Lillo-Le Louet et al reported a score for diagnosing heparin-induced thrombocytopenia (HIT) following cardiopulmonary bypass. The authors are from Hopital Europeen Georges Pompidou, Assistance Publique-Hopitaux de Paris and INSERM U428 in Paris.
Patient selection: cardiopulmonary bypass
Parameters:
(1) platelet count time course
(2) time from cardiopulmonary bypass to index date (date when HIT suspected)
(3) duration of cardiopulmonary bypass
Platelet Count Time Course
Fall in Platelet Count
pattern A
> 4 days after bypass, typically biphasic
pattern B
immediately after bypass; persists or worsens for more than 4 days
Parameter
Finding
Points
platelet count time course
pattern A
2
pattern B
1
other
0
time from surgery to index date
< 5 days
0
>= 5 days
2
duration of bypass
<= 118 minutes
1
> 118 minutes
0
total score =
= SUM(points for all 3 parameters)
Interpretation:
• minimum score: 0
• maximum score: 5
• The higher the score the greater the probability of heparin-induced thrombocytopenia.
Score
Probability of HIT
< 2
low
>= 2
high
Performance:
• The negative predictive value was 97%.
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