Association of Thrombocytopenia and Mortality in Critically Ill Patients on Continuous Renal Replacement Therapy.

BACKGROUND: Both acute kidney injury (AKI) requiring dialysis and thrombocytopenia are very common and have been independently associated with mortality and morbidity in critically ill patients. Thrombocytopenia is an independent risk factor for AKI and also a marker of disease severity. There is a paucity of literature on the prevalence, incidence, and outcome of thrombocytopenia in patients receiving continuous renal replacement therapy (CRRT). We aimed at identifying the impact of thrombocytopenia on patients in the intensive care unit (ICU) with AKI requiring CRRT.

METHODS: We retrospectively studied consecutive adult patients admitted to the ICU from December 9, 2006 through December 31, 2009, with follow-up for 12 months who received CRRT. Thrombocytopenia was defined as platelet counts of <150,000/µl and severe thrombocytopenia as platelet counts of <50,000/µl. Outcomes were mortality and length of stay, both in ICU and hospital. Descriptive summary and multivariable regression model were used for data analyses.

RESULTS: Out of the 541 patients studied, thrombocytopenia was observed in 350 (65%) prior to the initiation of CRRT, and 107 (20%) developed it after CRRT was started. The average age of patients was 61 ± 15; 328 (61%) were men. Sepsis was present in more than half of the patients requiring CRRT. We found a graded increase (p = 0.01) in ICU mortality with worsening platelet counts; 33, 40, and 51% of patients died in ICU with platelet counts ≥150,000/μl, 50,000-149,000/μl, and ≤50,000/µl, respectively. Thrombocytopenia prior to the initiation of CRRT and severe thrombocytopenia prior to and following the initiation of CRRT were associated with increased ICU mortality (p = 0.01).

CONCLUSIONS: Thrombocytopenia is very common in ICU patients who are on CRRT, and both thrombocytopenia prior to the start of CRRT and severe thrombocytopenia developing after the initiation of CRRT significantly impact patient survival. Future large-scale prospective studies will help to explore the role of platelet in prognostication of outcome among CRRT patients.