Objective: To determine prevalence, risk factors, and outcome of thrombocytopenia in medical intensive care patients.
Design: Prospective observational study.
Setting: The 12-bed medical intensive care unit of a university hospital.
Patients: All consecutively admitted patients with normal platelet count at admission and an intensive care unit stay of >48 hrs during a 13-month period (n = 145).
Measurements and main results: The prevalence of intensive care unit-acquired thrombocytopenia (platelet count, <150.0/nL) was 64 of 145 patients (44%). Intensive care unit mortality was 31% in thrombocytopenic patients and 16% in nonthrombocytopenic patients (p =.03). Mortality was higher in patients with a nadir platelet count of <100.0/nL (p <.001) and in patients with a drop in platelet count of >/=30% (p <.001). In nonsurvivors, the decrease in platelet count was greater (p <.001), the nadir platelet count lower (p <.001), and the duration of thrombocytopenia longer (p =.008) than in survivors. A logistic regression analysis identified septic shock (odds ratio [OR], 3.65; 95% confidence interval [CI], 1.40-9.52), a higher Acute Physiology and Chronic Health Evaluation II Score at admission (OR, 1.06 for 1 point; 95% CI, 1.01-1.12), and a drop in platelet count exceeding 30% (OR, 3.73; 95% CI, 1.24-11.21), but not thrombocytopenia, as independent risk factors for intensive care unit death. Correction of thrombocytopenia was associated with reduced mortality (OR, 0.002; 95% CI, 0-0.08). Major bleeding prevalence and transfusion requirements were significantly higher with thrombocytopenia. Nadir platelet count was the only independent risk factor for bleeding (OR, 4.1 for every 100.0/nL; 95% CI, 1.9-8.8). Independently associated with thrombocytopenia were disseminated intravascular coagulation (OR, 14.94; 95% CI, 3.92-57.00), cardiopulmonary resuscitation as an admission category (OR, 5.17; 95% CI, 1.42-18.85), and a higher Sequential Organ Failure Assessment score (OR, 1.20 for a 1 point change; 95% CI, 1.02-1.40).
Conclusions: Thrombocytopenia is common in medical intensive care unit patients. Thrombocytopenic patients have a higher prevalence of bleeding and greater transfusion requirements. A drop in platelet counts of > or = 30%, but not thrombocytopenia per se, is independently associated with intensive care unit death. Serial measurements of platelet counts are important and readily available markers for monitoring the patient's condition. Any drop in platelet count requires urgent clarification. Disseminated intravascular coagulation, signs of organ failure at admission, and cardiopulmonary resuscitation are predictors of intensive care unit-acquired thrombocytopenia.