Evolution and Impact of Thrombocytopenia in Septic Shock: A Retrospective Cohort Study

Objectives: To characterize the prevalence, incidence, and temporal evolution of thrombocytopenia (platelets < 100 × 10 9 /L) in septic shock and to investigate the independent association of thrombocytopenia on clinical outcomes. Design: Retrospective, propensity-matched, cohort study. Setting: Two academic ICUs in Winnipeg, Canada. Patients: Nine-hundred eighty adult patients diagnosed with septic shock between 2007 and 2012. Interventions: Propensity-matched cohort analysis and Cox proportional hazard model evaluating thrombocytopenia over time. Measurements and Main Results: Of 980 adults, 165 patients (16.8%) had thrombocytopenia at ICU admission (prevalent), whereas 271 (27.7%) developed thrombocytopenia during ICU admission (incident). Among patients with incident thrombocytopenia, the median time from ICU admission to thrombocytopenia was 2 days (interquartile range, 1–3 d). Among survivors, the median time from incident thrombocytopenia to platelet recovery was 6 days (interquartile range, 4–8 d). The median time from liberation of vasopressors to recovery of platelets concentration (≥ 100 × 10 9 /L) was 2 days (interquartile range, 0–4 d). In a propensity-matched analysis, thrombocytopenia was associated with increased durations of ICU length of stay (9 vs 6 d; p < 0.01), mechanical ventilation (7 vs 4 d; p < 0.01), and vasopressor use (4 vs 3 d; p < 0.01), as well as increased major bleeding events (41% vs 18%; p < 0.01). In an adjusted Cox proportional hazards model, thrombocytopenia was significantly associated with both increased ICU mortality (hazard ratio, 1.99; 95% CI, 1.51–2.63) and hospital mortality (hazard ratio, 1.93; 95% CI, 1.48–2.51). Conclusions: Both the prevalence and incidence of thrombocytopenia are high in septic shock. Incident thrombocytopenia occurs early in septic shock, and platelet recovery lags behind clinical recovery. In septic shock, thrombocytopenia is associated with increased length of stay, longer duration of organ support, major bleeding events, and mortality.