Acute appendicitis is one of the most frequent treated diseases in general surgery. Despite immediate surgery and improvements in diagnostics the rate of perforated appendicitis is reported up to 30%. The aim of this retrospective investigation was to identify risk factors for perforated and complicated appendicitis and establish a preoperative clinical risk score to evaluate patients regarding perforation.

A retrospective study was performed on the basis of clinical data of patients undergoing appendectomy during February 2010 and July 2017. Patients were divided into two groups on the basis of intraoperative findings and histological diagnosis: complicated and perforated appendicitis and a control group without perforation. Patients’ characteristics, clinical findings, laboratory parameter, sonography and CT scans were assessed and risk factors for perforated appendicitis were identified. Univariate and multiple logistic regression analysis of the two groups were performed to detect risk factors and to develop a risk score model for perforated appendicitis.

In total, 1001 patients were analysed, in 216 patients (21.6%) a perforated appendicitis was found. In univariate analysis age, BMI, ASA score, pain in lower right quadrant, rebound tenderness, positive clinical signs for Mc Burney and Blumberg, duration of pain longer than 72 hours, fever, chills, stool abnormalities, elevated leucocytes and CrP values were statistically significant between the two groups. In multiple logistic regression analysis age, rebound tenderness, duration of abdominal pain, body temperature >37.5°C and elevated CrP remained statistically significant for perforated appendicitis and were used for the development of the risk score. For each clinical sign categories were defined and a number was calculated for each category. Finally, a score point between 0 (1.51%) to 36 (97.15%) reflects the risk for perforated appendicitis. After ROC curve and area under the curve analysis the sensitivity and specificity was 82.1% and 80.6% respectively.

On the basis of five clinical parameters: age, duration of pain, rebound tenderness, CrP value, and body temperature, a risk score for perforated appendicitis was developed. This risk score could help in the future to detect patients with perforated appendicitis and guide the further treatment of these patients.