Clinical prediction of complicated appendicitis: A case-control study utilizing logistic regression
Yosuke Sasaki, Fumiya Komatsu, Naoyasu Kashima, Takeshi Suzuki, Ikutaka Takemoto, Sho Kijima, Tadashi Maeda, Taito Miyazaki, Yoshiko Honda, Hiroaki Zai, Nagato Shimada, Kimihiko Funahashi, Yoshihisa Urita
Abstract
BACKGROUND: Since high-quality evidence on conservative treatment of acute appendicitis using antibiotics has increased, differentiation of patients with complicated appendicitis (CA) from those with simple appendicitis (SA) has become increasingly important. Previous studies have revealed that male gender, advanced age, comorbid conditions, prehospital delay, fever, and anorexia are risk factors of perforated appendicitis. Elevated serum C-reactive protein (CRP) level and hyponatremia have also been reported as predictive biomarkers of CA. However, confounding between various factors is problematic because most previous studies were limited to univariate analysis. AIM: To evaluate non-laboratory and laboratory predictive factors of CA using logistic regression analyses. METHODS: We performed an exploratory, single-center, retrospective case-control study that evaluated 198 patients (83.9%) with SA and 38 patients (16.1%) with CA. Diagnoses were confirmed by computed tomography images for all cases. We compared age, sex, onset-to-visit interval, epigastric/periumbilical pain, right lower quadrant pain, nausea/vomiting, diarrhea, anorexia, medical history (of previous non-surgically treated appendicitis, diabetes, hypertension, dyslipidemia, liver cirrhosis, hemodialysis, chronic lung diseases, malignant tumors, immunosuppressant use, and antiplatelet use), vital signs, physical findings, and laboratory data to select the explanatory variates for logistic regression. Based on the univariate comparisons, we performed logistic regression for clinical differentiation between CA and SA using only non-laboratory factors and also including both non-laboratory and laboratory factors. RESULTS: (Model 2) showed that only elevated CRP levels had significantly high odds ratios. Under the curve values of receiver operating characteristics curves of each regression model were 0.74 for Model 1 and 0.87 for Model 2. CONCLUSION: Our logistic regression analysis on differentiating factors of CA from SA showed that high CRP level was a strong dose-dependent predictor of CA.