Etiology and clinical relevance of elevated platelet count in ICU patients : A retrospective analysis.

BACKGROUND: Thrombocytosis is a common phenomenon in critically ill patients. Although thrombocytosis is an independent risk factor for complications, it does not seem to influence mortality in intensive care (ICU) patients.

OBJECTIVES: Our investigation aimed to evaluate the etiological and clinical relevance of a platelet count greater than 450 × 109 /l in ICU patients.

MATERIALS AND METHODS: Patients admitted for a minimum of 4 days to an interdisciplinary ICU during a 45-month period were enrolled in this retrospective observational study. Thrombocytopenic patients (platelet count <150 × 109 /l in at least one measurement) were excluded. The study patients were divided into two groups: thrombocytosis group (thrombocytes >450 × 109 /l in at least one measurement) and control group (thrombocytes = 150 - 450 × 109 /l during ICU stay). Univariate and multiple regression analysis were used to determine the influence of severe co-morbidities on the development of thrombocytosis and the association of elevated platelet count with thrombotic embolism, length of stay (LOS) in ICU, and mortality.

RESULTS: A total of 307 patients were analyzed, of whom thrombocytosis was observed in 119 cases. Independent risk factors for the development of thrombocytosis included SIRS, mechanical ventilation, and acute bleeding. Increasing age reduced the risk of thrombocytosis. Thromboembolism occurred in 16 patients (13.4%) with an elevated platelet count and only in nine patients (4.7%) with physiological platelet values (OR: 3.1; 95% CI: 1.3-7.2; p = 0.009). Mean duration of LOS was significantly longer in patients with thrombocytosis (25.2 vs.11.7 days, p < 0.0001). Elevated platelet count showed a negative correlation with ICU mortality (OR: 0.32; 95%-CI: 0.12-0.83; p = 0.019).

CONCLUSION: In our retrospective analysis the occurrence of thrombocytosis in a cohort of interdisciplinary ICU patients was associated with a higher rate of complications and longer LOS in the ICU. Despite these findings, thrombocytosis seems to reduce mortality in critical ill patients.