The sensitivity and specificity of two clinical pathways for suspected appendicitis among children three to eighteen years old in a tertiary hospital
Objective: To describe the clinical characteristics of patients with abdominal pain, to determine the diagnostic accuracy of both scoring systems including the sensitivity and specificity of the Alvarado Scoring System (AS) and Samuel’s Pediatric Appendicitis Score (SPAS) among patients presenting in the emergency room with acute abdominal pain. A second objective was to evaluate whether or not imaging studies (abdominal ultrasound and CT scan) increases the diagnostic accuracy of either clinical pathway.
Design: Retro prospective, cross sectional study
Setting: St. Luke’s Medical Center, Quezon City, a tertiary, private institution
Participants: Three hundred fifty pediatric patients with complaints of abdominal pain who sought consult in the emergency department where acute appendicitis could not be ruled out were included in the study. Patients who were pregnant, with a chronic medical condition, or who undergone previous abdominal surgery, and those who had radiologic studies (CT or AUS) of the abdomen within the previous 2 weeks were excluded in the study,
Main Outcome measure: The specificity, sensitivity, positive and negative likelihood ratios of the two clinical pathways (Alvarado Score and Samuel’s Pediatric Appendicitis Score) in the diagnosis of acute appendicitis. Effect of the ancillary tests in the diagnostic accuracy of the two clinical pathways for patients with equivocal score values.
Results: Of the 335 patients enrolled, 25 (7.46%) had appendicitis. An initial AS of 1-4 was noted in 197 (58.8%) patients, AS 5-6 in 94 (28.1%) and AS 7-10 in 44 (13.1%) patients. While for SPAS, 182 (54.3%) patients were noted to have a score of 1-3, 135 (40.3%) patients with a score of 4–7 and 18 (5.4%) patients with SPAS of 8–10. Diagnostic imaging was done in 54 of 335 patients (16%), AUS was done in18/54 (33%) patients, 3 out of the 18 turned out positive for appendicitis. An abdominal computed tomography scan was requested in 36 of 54 (67%)patients, and 12 of 36 were positive for appendicitis. The overall diagnostic accuracy of AS (cut off ≤4, ≥7) alone was 90.8% with a sensitivity of 100%, specificity of 90%, moderate positive likelihood ratio of 10 and a low negative likelihood ratio of 0 whereas the overall accuracy of SPAS (cut off ≤3, ≥8) alone was 97%, with a sensitivity of 100%, specificity of 96.8%, high positive likelihood ratio of 25 and a low negative likelihood ratio of 0. When patients with equivocal scores were included, cutoff point of AS ≥7 revealed a sensitivity of 48% 98.6% specificity, 67% PPV, 96% NPV, LR+ 27, LR- 0.53 and overall accuracy of 73.4% and for SPAS≥8, revealed 84% sensitivity, 92.6% specificity, 48%PPV, 98.6%NPV LT+ 11.32, LR-0.17 and overall accuracy 88.3%. Overall diagnostic accuracy of AS with AUS was 90.9% and AS with CT scan was 91.2% whereas the overall diagnostic accuracy of SPAS with AUS was 96.6% and SPAS with CT scan was 96.4%.
Conclusions: Both scoring systems can be used as a practical aid in stratifying patients suspected of acute appendicitis in the emergency department, however, neither can be used as a sole diagnostic tool. For patients with equivocal score, further tests using abdominal ultrasonography or CT scan increased the diagnostic accuracy of both tests. However, there was no significant difference between the ultrasound and CT scan. Clinical judgment is the mainstay of diagnosing acute appendicitis.