title: In vitro thrombotic tendency of reactive thrombocytosis in critically ill patients: a prospective case-control study.
abstract: It is uncertain whether reactive thrombocytosis is associated with an increased risk of thrombosis. This prospective case-control study assessed the in vitro thrombotic tendency of patients with reactive thrombocytosis. Forty-eight patients with reactive thrombocytosis, defined by platelet count >500x10(9)/l and 55 similar, randomly selected critically ill patients who did not have reactive thrombocytosis were considered. In vitro thrombotic tendency in both groups of patients was assessed using maximal amplitude (normal range 54 to 72 mm) and alpha angle (normal range 47 to 74°) on the thromboelastograph. The associations between reactive thrombocytosis and C-reactive protein, the coagulation profile and Sequential Organ Failure Assessment score were also evaluated. Patients with reactive thrombocytosis had an associated increased in vitro thrombotic tendency (maximal amplitude 77 vs 69 mm, mean difference 8 mm, 95% confidence interval 4.9 to 10.9, P=0.001), a higher fibrinogen concentration (7.2 vs 5.8 g/l, P=0.003), and a higher incidence of infection requiring antibiotics (50 vs 27%, P=0.025) compared to patients without thrombocytosis. Platelet count had a relatively linear relationship with the maximal amplitude and the alpha angle of the thromboelastograph tracing (Pearson correlation coefficient: 0.53, P=0.001). In the multivariate analysis, only reactive thrombocytosis (odds ratio 5.9, 95% confidence interval 1.3-27.8, P=0.025) and activated partial thromboplastin time (odds ratio 0.93 per second increment, 95% confidence interval 0.87 to 0.99, P=0.016) were significantly associated with a strong in vitro thrombotic tendency. In summary, reactive thrombocytosis was associated with infection requiring antibiotics and evidence of increased in vitro thrombotic tendency in critically ill patients.
authors.affiliation: Department of Intensive Care, Royal Perth Hospital, Perth, Western Australia, Australia.
authors.forename: O C
authors.initials: OC
authors.lastname: Duff
authors.forename: K M
authors.initials: KM
authors.lastname: Ho
authors.forename: S M
authors.initials: SM
authors.lastname: Maybury
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D015331:Cohort Studies; D016638:Critical Illness / Q000628:therapy*; D003625:Data Collection; D005260:Female; D019763:Heparin Lyase; D006801:Humans; D007616:Kaolin; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010976:Platelet Count; D011446:Prospective Studies; D013916:Thrombelastography; D013922:Thrombocytosis / Q000628:therapy*; D013927:Thrombosis / Q000150:complications*; D055815:Young Adult
chemical_list: D007616:Kaolin; D019763:Heparin Lyase