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.
Publisher
University of Nairobi