Low-molecular-weight heparins and thrombocytosis.
BACKGROUND
A possible association between low-molecular-weight heparins (LMWHs) and thrombocytosis was suspected from spontaneous reports to the French Pharmacovigilance System. This association is not mentioned in LMWH's summary of product characteristics.


METHODS
All case records in the French Pharmacovigilance database were reanalyzed for relevance and causality, and the case/noncase approach was used including reports of thrombocytosis as cases and all other reports as noncases.


RESULTS
Fifty-one patients treated with LMWHs had platelet counts >500 x 10(3)/mm(3). All patients were asymptomatic, and 1 had a positive rechallenge. There were 143 cases of thrombocytosis among the 174 213 reports in the database, with 61 of 4644 involving LMWHs. The calculated relative reporting ratio is 27.5 (p < 0.0001; 95% CI 19.5 to 38.9).


CONCLUSIONS
There is a highly significant association of thrombocytosis reported with LMWH treatment.
Centre Antipoison, Centre de Pharmacovigilance, Hôpital Edouard Herriot, Lyon, France. jacques.descotes@chu-lyon.fr
Christine
C
Liautard
Ana-Maria Correa
AM
Nunes
Thierry
T
Vial
Fabienne
F
Chatillon
Claire
C
Guy
Michel
M
Ollagnier
Jacques
J
Descotes
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects*; D016208:Databases, Factual; D005260:Female; D005602:France / Q000453:epidemiology; D006495:Heparin, Low-Molecular-Weight / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D011358:Product Surveillance, Postmarketing; D013922:Thrombocytosis / Q000139:chemically induced* / Q000453:epidemiology
D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight