On bivariate analyses, SpO2, RR, morphine use, pain localization, leukocyte, reticulocyte and neutrophil counts, and Hb, LDH, and AST levels at admission were associated with ACS development but not symptom duration before admission, temperature, HR, CRP level, platelet count, or fibrinogen, bilirubin, and HbF levels (Table 2). This evidence concerns the gene CRP and acute chest syndrome.