One in five patients using heparin to protect against venous thromboembolism (VTE) develops thrombocytopenia, reveal results from the CATCH (Complications After Thrombocytopenia Caused by Heparin) Registry.
Heparin-induced thrombocytopenia (HIT) - defined as a 50% reduction in platelet count or a nadir of 150x109/L within 72 hours of treatment - occurred in 18.7% of 1017 US patients given heparin thromboprophylaxis at 48 hospitals between 2003 and 2004.
However, just 5.8% of patients were diagnosed with thrombocytopenia before discharge, serologic testing was performed in just 5.3% of patients with HIT, and only 3.2% of patients had a hematology consult.
Of concern, just one of the 11 patients known to have a high risk for HIT according to the Warkentin criteria was tested for HIT. It took a median of 101 hours before treatment was ceased in this population, and 162 hours in the overall population, with heparin stopped in just 5.3% of patients within 24 hours of HIT. None of the patients were switched to a direct thrombin inhibitor.
"Our findings support the need for vigilant platelet monitoring, particularly among patients at high risk of thrombocytopenia receiving heparin for venous thromboembolism prophylaxis, with careful consideration of subsequent anticoagulation management to avoid downstream adverse outcomes," say Tracy Wang (Duke Clinical Research Institute, Durham, North Carolina, USA) and co-investigators.
"Further investigation is needed to determine the optimal approach to managing thrombocytopenia so patient outcomes can be improved."
They note that HIT was associated with a significant 4.49-fold increased risk for Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) moderate or severe bleeding, although there was no significant increase in the risk for the combined endpoint of in-hospital mortality and VTE.
HIT was significantly predicted by use of a ventilator (adjusted odds ratio [OR]=2.43) and duration of heparin treatment (adjusted OR=1.09 per day), as well as baseline platelet count (adjusted OR=0.86-1.09).
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