A combination of preoperative serum direct bilirubin and neutrophil–lymphocyte ratio can discriminate cases of complicated appendicitis

Objectives
Evaluation of the ability of routine investigations for patients presenting with acute right lower abdominal pain for preoperative prediction of complicated appendicitis (CA).
Patients and methods
In all, 311 patients who had acute appendicitis were evaluated clinically and by abdominal ultrasonography and obtained blood samples for the estimation of serum C-reactive protein (CRP), direct bilirubin (DB), determination of total leukocyte count, and for the calculation of neutrophil/lymphocyte ratio (NLR). Patients were categorized according to operative findings as CA or uncomplicated appendicitis (UCA). The diagnostic performance of the estimated variables was statistically evaluated as predictors for CA.
Results
Patients who had CA were mostly males and older than those who had UCA. Preoperative abdominal ultrasonography diagnosed mild, moderate, and severe acute appendicitis in 138, 136, and 37 cases, respectively. Operative findings defined 48 patients had CA and 263 as having UCA. Preoperative total leukocyte count and NLR, and serum CRP and DB were significantly (<0.001) higher in CA than in UCA patients. Statistical analyses defined high serum DB, high NLR, and high serum CRP as positive preoperative predictors for CA in the decreasing order of significance. Kaplan–Meier analysis defined serum DB level at 0.51±0.03 mg/dl [95% confidence interval (CI): 0.471–0.589], NLR at a level of 4.7±0.04 (95% CI: 4.62–4.84), serum CRP at 13±1.6 (95% CI: 12.3–13.5) as predictors for CA in decreasing positive predictive and specificity values. The percentage of true positive cases of CA in comparison to operative findings was 79.2% on using DB and NLR, 72.9% on using a combination of CRP and NLR, 68.8% with DB and CRP combination, and 87.5% with a combination of DB, CRP, and NLR.
Conclusion
Preoperative routine laboratory investigations can discriminate against CA cases. Combined estimation of DB and determination of NLR with or without estimation of serum CRP provided a high discriminative ability for CA cases.