The outcome of patients with acute venous thromboembolism (VTE) and abnormal platelet count (PlC) at baseline has not been consistently studied. In real-world clinical practice, a number of patients with abnormal PlC receive vitamin K antagonists (VKAs) to treat acute VTE despite their higher risk of bleeding.
We used the Registro Informatizado de Enfermedad TromboEmbólica registry database to compare the rate of major bleeding in patients receiving VKA for long-term therapy of acute VTE according to PlC levels at baseline. Patients were categorized as having very low (<100,000/μL), low (100,000–150,000/μL), normal (150,000–300,000/μL), high (300,000–450,000/μL), or very high (>450,000/μL) PlC at baseline.
Of 55,369 patients recruited as of January 2015, 37,000 (67%) received long-term therapy with VKA. Of these, 611 patients (1.6%) had very low PlC, 4006 (10.8%) had low PlC, 25,598 (69%) had normal PlC, 5801 (15.6%) had high PlC, and 984 (2.6%) had very high PlC at baseline. During the course of VKA therapy (mean, 192 days), there were no differences in the duration or intensity (as measured by international normalized ratio levels) of treatment between subgroups. The rate of major bleeding was 3.6%, 2.1%, 1.9%, 2.1%, and 3.7%, respectively, and the rate of fatal bleeding was 0.98%, 0.17%, 0.29%, 0.34%, and 0.50%, respectively. Patients with very low or very high PlC levels were more likely to have severe comorbidities.
We found a nonlinear “U-shaped” relationship between PlC at baseline and major bleeding during therapy with VKA for VTE. Consistent alteration of PlC values at baseline suggested a greater frailty.
From the Emergency Department, Val d’Arda Hospital, Piacenza, (MGP, CC); Department of Internal Medicine, Ospedale Buonconsiglio Fatebenefratelli, Naples, (PDM); University Hospital “San Giovanni di Dio e Ruggi d’Aragona”, Salerno (AG); Department of Internal Medicine, Hospital de Madrid Norte Sanchinarro (BP); Department of Internal Medicine, Hospital del Tajo, Madrid, Spain (MDVM); Intensive Care Unit, Hospital Clinica La Merced, Quito, Ecuador (ES); Department of Internal Medicine, Hospital Vall d[Combining Acute Accent]Hebrón (JMS); Department of Internal Medicine, Corporación Sanitaria Parc Tauli, (CT); and Department of Internal Medicine, Hospital Universitari Germans Trias i Pujol, Badalona, Barcelona, Spain (MM).
Correspondence: Matteo Giorgi-Pierfranceschi, MD, Emergency Department, Val d’Arda Hospital, Piacenza, Italy (e-mail: firstname.lastname@example.org).
Abbreviations: DVT = deep vein thrombosis, INR = international normalized ratio, LMWH = low molecular weight heparin, MB = major bleeding, PE = pulmonary embolism, PlC = platelet count, RIETE = Registro Informatizado de Enfermedad TromboEmbólica, VKA = vitamin K antagonist, VTE = venous thromboembolism.
A full list of the RIETE investigators is given in the appendix.
The authors have no conflicts of interest to disclose.
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Received September 24, 2015
Received in revised form October 4, 2015
Accepted October 7, 2015