AA, acute appendicitis; NAP, nonspecific abdominal pain; AUC, area under curve; PPV, positive predictive value; NPV, negative predictive value; CI, confidence interval; CRP, C-reactive protein; WBC, white blood cells; RDW, red cell distribution width; NEU, neutrophil; LYM, lymphocyte; MON, monocyte; NLR, neutrophil-to-lymphocyte ratio; RLR, RDW-to-lymphocyte ratio; MLR, monocyte-to-lymphocyte ratio; SII, systemic immune inflammation index. The gene discussed is CRP; the disease is appendicitis.