Abstract Background Normalization of C-reactive protein (CRP) is a key STRIDE-II therapeutic target in the management of inflammatory bowel disease (IBD). Evidence regarding its prognostic value after switching biological therapy due to loss of response is still limited. This study aimed to assess CRP normalization following a biologic switch in patients experiencing a clinical flare and to evaluate its association with clinical response. Methods In this prospective cohort study, adults with Crohn’s disease or ulcerative colitis underwent a change in biological therapy due to clinically assessed disease exacerbation, defined by the Harvey–Bradshaw Index or the Mayo Clinical Score. Patients were reassessed at their next clinic visit with clinical and biochemical evaluation. The primary endpoint was CRP normalization (5 mg/L). The secondary endpoint was its association with clinical response. Fisher’s exact test was used, with results reported as odds ratios (OR) and 95% confidence intervals (CI). Results Thirty-three patients were included. Mean age was 39.9 years and 48.5% were male. Baseline CRP averaged 29.5 mg/L, and 63.6% were receiving concomitant immunomodulators. Following the switch in biological therapy, 69.7% (n = 23) achieved CRP normalization. CRP normalization was significantly associated with clinical response (OR 9.1; 95% CI: 1.8–95; p = 0.01), indicating markedly higher odds of improvement among patients achieving CRP 5 mg/L. Conclusion Switching biological therapy during disease flare resulted in CRP normalization in most patients. CRP normalization was strongly associated with clinical response, supporting its potential value as an early biochemical marker after therapeutic switching. Larger prospective studies are needed to validate its prognostic significance and to refine biomarker-driven treatment strategies in IBD. Conflict of interest: Mrs. Vlachou, Evangelia: No conflict of interest
E Vlachou (Thu,) studied this question.