The Frequency and Clinical Significance of Thrombocytopenia Complicating Critical Illness: A Systematic Review

The epidemiology of thrombocytopenia in critically ill patients has not been well characterized. The objective of this study was to systematically review the prevalence, incidence, risk factors for, and consequences of thrombocytopenia among critically ill patients.

We searched MEDLINE, EMBASE, the Cochrane Registry for controlled trials (until May 2010), and the Online Computer Library as well as bibliographies of relevant studies to identify investigations designed to examine the frequency, risk factors and/or outcomes associated with thrombocytopenia among patients admitted to the intensive care unit (ICU). We selected studies, abstracted data and assessed methodological quality in duplicate, independently. Heterogeneity of design and analysis precluded statistical pooling of results.

We identified 23 studies (12 prospective) enrolling 6,568 patients from medical, surgical, mixed, cardiac or trauma ICUs. Prevalent thrombocytopenia (on ICU admission) occurred in 8.3 – 67.6% of patients; incident thrombocytopenia (developing during the course of the ICU stay) occurred in 13.0 – 44.1% patients. High illness severity, organ dysfunction, sepsis and renal failure were common risk factors. Only 1 study using multivariate analysis examined whether thrombocytopenia was associated with major bleeding but found no association. Six out of 8 studies using multivariate analysis found that thrombocytopenia increased the risk of death.

The frequency of thrombocytopenia during critical illness varies widely based on case mix and definition. Thrombocytopenia appears to increase the risk of death after adjustment for confounding factors. The association between thrombocytopenia and bleeding in the ICU has not been adequately examined. Although thrombocytopenia was associated with poor outcomes in most studies, randomized trials of platelet transfusions or other interventions aimed at increasing the platelet count are needed to determine whether improvement of thrombocytopenia can modify these risks.

No relevant conflicts of interest to declare.