An appendicitis severity index (APSI) is an accurate and simple prediction of complicated appendicitis in adults, according to a study published in the journal European Radiology.
Researchers from Germany sought to determine a routinely applicable severity index for the management of acute appendicitis in adults using combined clinical and radiological parameters and retroperitoneal space planes (RSP).
The researchers retrospectively analyzed data from 200 adults with histologically proven acute appendicitis and available presurgical CT scans. Two radiologists assessed all CT scans for morphologic sings of appendicitis and six RSP.
Clinical parameters included:
• Body temperature
• C-reactive protein (CRP)
• White blood cell count
• Duration of symptoms
Radiological parameters included:
• Appendix diameter and wall thickness
• Periappendiceal fat stranding and fluid
• Intraluminal and extraluminal air
• Thinning of appendiceal wall
• Caecal wall thickening
• Abscess formation
The results showed that 103 of the 200 patients, 51 percent, had histologically proven complicated appendicitis. The APSI was developed using regression coefficients of multivariate logistic regression analyses with a maximum of 10 points based on three clinical (age 52 years or older, body temperature of 37.5°C or higher, duration of symptoms for 48 hours or longer,) and four CT findings (appendix diameter of 14 mm or larger, presence of periappendiceal fluid, extraluminal air, perityphlitic abscess).
A score of four or more points predicted complicated appendicitis with a positive predictive value of 92 percent and a negative predictive value of 83 percent. Substantial to excellent interobserver agreement was found for the four radiological parameters of the APSI. The RSP evaluation presented no added value for the diagnosis of complicated appendicitis.
The researchers concluded that using APSI allowed for accurate and simple prediction of complicated appendicitis in adults. The RSP count was not useful for the diagnosis of complicated appendicitis.