[Heparin-induced thrombocytopenia after elective hip joint replacement with postoperative prevention of thromboembolism with low-molecular-weight heparin].
BACKGROUND
Heparin-induced thrombocytopenia (HIT) is a severe side effect of the prophylaxis of venous thromboembolism with unfractionated heparin. The aim of the present study is to gain more information on the incidence of HIT during prophylaxis of venous thromboembolism with low-molecular-weight heparin in elective hip surgery.


METHODS
586 consecutive patients were included into the prospective study, who were admitted to hospital for elective hip replacement. The incidence of thrombocytopenia, clinically manifest venous thromboembolism and of the heparin-induced IgG antibodies were analysed during prophylaxis with low molecular-weight heparin. Patients received once daily subcutaneously low molecular-weight heparin for a mean of 28 days postoperatively. Platelet counts and clinical examinations for the presence of venous thromboembolism were done at days 0, 2, 7 (+/- 1) and 12 (+/- 2). Heparin-induced IgG antibodies were determined before and after a 12 (+/- 2) days prophylaxis with low molecular-weight heparin in 265 of 586 patients randomly. Patients were reexamined for thromboembolic complications after 3 and 6 months. The clinical suspicion of thromboembolic complication was documented objectively.


RESULTS
None of the patients developed a decrease of platelets of < 50% of the initial value. Ten of 265 patients had elevated IgG antibodies against heparin/platelet factor 4 before prophylaxis (3.8%). After the 12 (+/- 2) days prophylaxis 13 of 265 patients had elevated IgG antibodies (4.9%). C14 serotonin assay was positive in 0 of 10 patients before treatment and in 3 of 19 patients at day 12 (+/- 2). Ten patients developed venous thromboembolism postoperatively (8 x deep venous thrombosis, 2 x pulmonary embolism, no fatal embolism). Only 1/19 patients with elevated antiheparin IgG titres developed venous thromboembolism. The C14 serotonin assay was negative in this patient. Two patients died in the postoperative phase due to underlying cardiovascular diseases.


CONCLUSIONS
In patients with elective hip replacement prophylaxis of venous thromboembolism with low molecular-weight heparin was associated with a very low incidence of HIT, and hence screening for HIT antibodies is not required.
Marx
A
A
I. Medizinische Klinik, Universitätsklinikum Mannheim, Klinikum Mannheim GmbH.
Huhle
G
G
Hoffmann
U
U
Wang
L C
LC
Schüle
B
B
Jani
L
L
Harenberg
J
J
D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D008875:Middle Aged; D010976:Platelet Count / Q000187:drug effects; D011183:Postoperative Complications / Q000097:blood / Q000517:prevention & control*; D011446:Prospective Studies; D012701:Serotonin / Q000097:blood; D013921:Thrombocytopenia / Q000097:blood / Q000139:chemically induced*; D013923:Thromboembolism / Q000097:blood / Q000517:prevention & control*
D006495:Heparin, Low-Molecular-Weight; D012701:Serotonin