Challenges of preanalytical variables in erythrocyte sedimentation rate: a CUBE 30 touch evaluation

The erythrocyte sedimentation rate (ESR) is a widely used diagnostic test, influenced by all physiological and pathological conditions that can bias blood rheology by interfering factors. This study aimed to evaluate the performance of the CUBE 30 touch ESR analyzer in samples with preanalytical variables, as lipemia, hemolysis, and icterus or in presence of fibrinogen., Moreover we focused to define the maximum time limits to ensure a reliable ESR measure. Accuracy, intra-run and inter-run precision, and stability studies were performed. Moreover, hemolytic, jaundiced, lipemic samples and fibrinogen sensitivity were analyzed for interference study. Statistical analyses were performed. CUBE 30 touch and Westergren method comparison showed no statistical differences (Spearman Coefficient, R²=0,95). In the intra-run precision, the CV% mean obtained on samples with normal ESR level was 8,9%; with middle ESR level was 5,9% and with high ESR level the CV% was 4,3%. Inter-run precision test showed CV% of for single samples and overall samples in the range (12,3% for normal level and 4,8% for abnormal level). The samples stored at 4 °C showed good stability up to 3 h from collecting time. ESR samples showing lipemia, hemolysis or jaundice showed good correlations with the gold standard method (R² 0,901, 0,940, 0,911; p < 0,0001), however, Westergren tests were more sensitive than CUBE 30 touch to fibrinogen additions. The high comparability with the Westergren method, both in normal and interfering samples, and the good precision, support the usefulness of CUBE 30 touch in the clinical routine laboratory.