Unnecessary repetitions of C-reactive protein and leukocyte count at the emergency department observation unit contribute to higher hospital admission rates.

Objectives: The aim of the present study was to assess the effect of repeated laboratory measurement of C-reactive protein (CRP) and leukocyte count on the decision whether to admit or dicharge the patient with localized infections who received antibiotics at the Emergency Department (ED) observation unit.

Methods: Adult patients with respiratory, urinary tract and abdominal infections, observed at the ED after antibiotic administration, in whom repeated measurements of CRP and leukocyte count were performed within 24 h, were included. They were initially grouped as planned discharge, planned admission and unclear attitude towards admission. Initial and repeated CRP and leukocyte count results, clinical dynamics (improvement, worsening, unchanged) and clinical decision about discharge or admission, were recorded.

Results: A total of 1,038 patients were eligible for inclusion. No significant differences in initial CRP and leukocyte count values were observed, nor any association of CRP and leukocyte count changes with clinical dynamics. Among 504 patients eligible for discharge at second laboratory sampling according to clinical dynamics, 54.4 % were further observed or admitted. Discharged patients had an average negative absolute (p<0.001) and relative CRP change (p=0.002). Clinical dynamics, first and second CRP results and absolute CRP change were independently associated with the decision to discharge or further observe/admit.

Conclusions: Schematic repetitions of CRP and leukocyte count at the ED observation unit are common, regardless of patients' clinical condition. Clinical judgment remains the main guiding factor to admit or discharge the patient, but repeated CRP testing influences the final decision, contributing to higher admission rates.