Estimated C-Reactive Protein Velocity and CT-Defined Complicated Appendicitis
2Division of Internal Medicine, Tel Aviv Sourasky Medical Center, Israel
Background
Computed tomography (CT) assessment of appendicitis severity may benefit from clinical and laboratory context. C-reactive protein (CRP) reflects inflammatory burden, but its interpretation may depend on symptom duration. We evaluated the association of estimated CRP velocity with CT-defined complicated appendicitis and compared its discrimination with admission CRP.
Methods
This retrospective single-center study included adults with pathologically confirmed appendicitis who underwent CT with CRP measured within three hours of CT during 2017–2025. From 1,103 patients, sampling across nine predefined CRP categories yielded 182 patients after exclusions. CT examinations were retrospectively reviewed. Complicated appendicitis was defined by appendiceal wall irregularity, intramural or periappendiceal collection, or free intraperitoneal air. Estimated CRP velocity was calculated as admission CRP divided by the reported symptom-to-CT interval. Receiver operating characteristic analysis assessed discrimination; a secondary analysis included 44 pairs matched for symptom duration.
Results
CT-defined complicated appendicitis was present in 68/182 patients (37.4%). Compared with uncomplicated cases, complicated cases had higher median CRP (125.8 versus 26.7 mg/L), estimated CRP velocity (2.3 versus 1.0 mg/L/h), and symptom duration (51.5 versus 26.5 hours; all p<0.001). CRP had the highest area under the curve (AUC), 0.880 (95% confidence interval (CI), 0.828–0.932), compared with estimated CRP velocity (0.746; 95% CI, 0.675–0.818) and symptom duration (0.739). After matching, CRP remained higher in complicated cases (118.1 versus 65.1 mg/L), as did estimated CRP velocity (2.5 versus 1.1 mg/L/h; both p<0.001).
Conclusions
CT-defined complicated appendicitis is associated with greater inflammatory burden even at comparable symptom duration, suggesting that elevated CRP reflects more than elapsed disease time. This finding highlights a potentially informative temporal dimension of the inflammatory response. Although CRP alone showed greater discrimination than estimated CRP velocity, these results provide a rationale for prospectively evaluating symptom timing in integrated laboratory and CT severity assessment.