Evaluation of total white blood cell count and neutrophil percentage in assessing the severity of acute appendicitis at Kenyatta national hospital.

Abstract

Introduction: Appendicitis is one of the most common causes of abdominal pain and indication for emergency abdominal surgery world over. History and physical examination remain the cornerstones of good clinical practice in patients presenting with acute abdominal pain localized in the right lower abdominal quadrant. Outcome of acute appendicitis is influenced by its severity. Previous studies done to determine the value of white cell count and NP in predicting severity of acute appendicitis had varied outcomes. This cross sectional study aimed to determine the value of preoperative evaluation of white blood cell (WBC) count and neutrophil percentage (NP) in predicting severity of acute appendicitis at Kenyatta National Hospital. Objective: To determine the value of WBC count and NP in assessing severity of acute appendicitis Study design: Cross sectional study Study site: Kenyatta National hospital accident and emergency unit, general and paediatric surgical wards and operating theatres. Methodology: Ethical approval was sought and granted from KNH\UON ERC. Data was collected from July to October 2014. We enrolled 119 patients who presented with features of acute appendicitis. Data including history, physical examination, total blood count, operative findings and histopathology, were obtained. One hundred and fifteen patients were analyzed. Four patients had other surgical diagnosis and appendicectomy was not performed. Patients were subdivided according to surgical and histological finding into: G0 for normal appendix n=13, G1 for acute appendicitis n=56, G2 for gangrenous acute appendicitis n=12, G3 for perforation n=10, G4 for perforated appendicitis with regional abscess n=24. Dependent variables were WBC count and NP. Independent variable was grade of appendicitis. Data analysis: using SPSS (version 17.0) software diagnostic performances of WBC and NP were analyzed. Receiver operating characteristic (ROC) curves were drawn and comparison of mean values of leukocytes and neutrophils between different degrees of appendicitis were performed using ANOVA. Results: WBCs and neutrophils counts were significantly higher in patients with inflamed and perforated appendicitis than normal appendix. In normal versus simple appendicitis the cutoff of WBCs count and NP was 9.64 X103 ml and 71.85%respectively. At these cut offs the sensitivity of 75.00 %, 66.07 (52.19 – 78.18) specificity of 30.77%, and 46.15; PPV of 82.35 and 84.78; NPV of 22.22% and 26.09; [LR(+)] of 1.08 and 1.29;and LR(−) of 0.81and 0.66respectively. At these cutoff points, AUC (95% CI) for WBC count and NP was 0.649and 0.648 respectively. The same parameters were used to discriminate normal from perforated appendicitis with cutoff values in WBCs and NP at 10.30 X103and 77.50% respectively. At these cutoff points, AUC (95% CI) for WBCs and NP were 0.796 and 0.777. WBCs and NP sensitivity were82.35 %,72.97% ;specificity38.46 %,69.23%,; PPV 77.78% and 87.10; NPV45.45 % and 47.37% ;LR(+)1.34 and 2.37 and LR(−)0.46 and 0.39.The predictive value for both WBC and NP for acute appendicitis was noted to increase with higher grades of appendicitis. Conclusion: Leukocyte and neutrophils counts alone cannot be used as diagnostic criteria for acute appendicitis because of its low sensitivity and specificity and must be correlated with clinical data for decision making. WBCs and neutrophils counts do not reliably indicate disease severity; the low sensitivity, specificity and AUC of these tests prove that they are insufficient to achieve reliable rule-out effect. This applies also in the ability of these two parameters to discriminate inflamed from perforated appendicitis.