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Thrombocytopenia in Critically Ill Patients Receiving Thromboprophylaxis
Study Question: What are the incidence, risk factors, and outcomes of thrombocytopenia in patients admitted to medical-surgical ICUs?
Study Description: This was a prespecified analysis of data from PROTECT, a multicenter, randomized, blinded trial comparing unfractionated heparin (UFH) to dalteparin to prevent lower extremity deep vein thrombosis (DVT). The categories of thrombocytopenia were mild (100 – 149 x 109/L), moderate (50 – 99 x 109/L) and severe (< 50 x 109/L).
Results: Of 3,639 patients who had platelet count on day of enrollment, 26.2% had platelet count < 150 x 109/L. The incidence of mild, moderate, and severe thrombocytopenia was 15.3%, 5.1%, and 1.6% respectively. Risk factors associated with the development of thrombocytopenia in all categories included APACHE II score, the receipt of inotropes or vasopressors, and renal replacement therapy in the preceding 3 days. In patients who developed moderate thrombocytopenia, additional associations included surgical admission and liver dysfunction, while the use of prophylactic low-molecular-weight heparin was associated with a lower risk. There was no association between stress ulcer prophylaxis and any category of thrombocytopenia. Patients in all categories of thrombocytopenia had a higher risk of subsequent bleeding and transfusions. ICU and hospital mortality were higher in patients who developed moderate and severe thrombocytopenia.
Conclusion(s): In critically ill medical-surgical patients who received thromboprophylaxis, incidence of mild/moderate thrombocytopenia is approximately 20%. A higher severity score, surgical admission, use of vasopressors/inotropes, renal replacement therapy, and liver dysfunction is associated with higher risk of thrombocytopenia.
Perspective: The findings of this study apply mainly to medical ICU admissions, which comprised approximately 80% of patients with a moderate degree of illness (APACHE II score ~22); patients with neurologic injury were excluded. Although the study examined whether an association existed between stress ulcer prophylaxis thrombocytopenia, one other analysis that would have been interesting is the relative efficacy of blood product use in the correction of thrombocytopenia.