Prognostic usefulness of white blood cell count on admission and one-year outcome in patients with non-ST-segment elevation acute chest pain.

Little is known about the prognostic value of leukocyte count on admission for patients with chest pain. In total, 1,461 patients who presented to the emergency department with non-ST-segment elevation chest pain were studied by clinical history, electrocardiography, serial troponin I determination, and leukocyte count on admission. End points were 1-year mortality and major events (mortality or infarction). Overall patient distribution by quartiles of leukocyte count showed increased mortality (6%, 7%, 6%, and 17%, p = 0.0001) and major events (13%, 13%, 15%, and 24%, p = 0.0001) in the fourth quartile. After adjustment for other risk factors, the fourth quartile cut-off value (>10,000 cells/ml) predicted mortality (hazard ratio 2.0, 95% confidence interval 1.4 to 2.8, p = 0.0001) but not major events (p = 0.07). When analysis was performed to assess troponin status, in the subgroup with increased troponin (n = 634, 16% mortality), a leukocyte count >10,000 cells/ml was related to mortality (hazard ratio 2.2, 95% confidence interval 1.5 to 3.4, p = 0.0001). However, in the subgroup with normal troponin levels (n = 827, 4.2% mortality), there were no differences in mortality between patients with or without a leukocyte count >10,000 cells/ml (4.4% vs 4.2%, p = 0.8), with survival curves showing a tight overlap (p = 0.9). Further, in the subgroup with normal troponin levels, leukocyte count was not significantly different between patients with or without ST depression (7,969 +/- 2,171 vs 8,108 +/- 2,356 cells/ml, p = 0.6) and was not associated with mortality in patients with ST depression (p = 0.7). In conclusion, leukocyte count on admission is predictive of mortality in patients with chest pain and non-ST-segment elevation myocardial infarction. However, in the absence of myocardial necrosis, leukocyte count lacks prognostic value.