Leukemoid reaction: spectrum and prognosis of 173 adult patients.

BACKGROUND The prognosis of patients with leukemoid reaction (LR) depends mainly on their underlying illness. Our aim was to investigate the etiologies and prognosis of a mixed group of patients with LR. METHODS We identified 173 patients who had ≥30.0 × 10(9) leukocytes/µL without hematologic malignancies. Causes of LR and factors contributing to death were analyzed. RESULTS Patients with LR constituted 0.59% of all admitted adults. The median age was 75 years, but 20 patients were aged <40 years. There was no difference in LR prevalence by gender (female/male = 88/85). Average white blood cell (WBC) count was 37.7 × 10(9)/µL. Fourteen patients (8.0%) had a WBC count of >50.0 × 10(9)/µL. The median duration of LR was 1 day, but 39 patients had prolonged LR (>1 day). Infection was the most common cause of LR (n = 83, 47.9%; 95% confidence interval, 40.7-55.4), followed by ischemia/stress (27.7%), inflammation (6.9%), and obstetric diagnoses (6.9%). Higher WBC counts were significantly associated with positive blood cultures (P = .017) or a positive Clostridium difficile toxin (P = .001). Antibiotics were prescribed for 140 patients (80.9%). Sixty-six patients (38.1%) died during hospitalization. Those with prolonged LR had an in-hospital mortality rate of 61.5%. Factors found to be highly correlated with death were age (odds ratio [OR] = 1.051, P < .001), any infectious diagnosis (OR = 2.574, P = .014), and sepsis (OR = 3.752, P = .001). CONCLUSIONS LR carries a grave prognosis, especially among the elderly and those with sepsis. LR was found to have multiple etiologies including infections, stress, inflammation, and obstetric diagnoses.