C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) or both? A systematic evaluation in pediatric ulcerative colitis.

BACKGROUND: There has not been an extensive comparison of CRP and ESR in ulcerative colitis (UC), and thus, we aimed to explore their utility in UC.
METHODS: Four previously enrolled cohorts of 451 children with UC were utilized, all including laboratory, clinical and endoscopic data. A longitudinal analysis was performed on prospectively collected data of 75 children. Disease activity was captured by both global assessment and pediatric UC activity index (PUCAI).
RESULTS: The best thresholds to differentiate quiescent, mild, moderate and severe disease activity, were <23, 23-29, 30-37, >37 mm/h for ESR, and <2.5, 2.5-5, 5.01-9, >9 mg/L for CRP (area under the ROC curves 0.70-0.81). Correlation of endoscopic appearance with CRP and ESR were 0.55 and 0.41, respectively (P<0.001). Both CRP and ESR may be completely normal in 34% and 5-10% of those with mild and moderate-severe disease activity, respectively. Elevated CRP in the presence of normal ESR or vice versa was noted in 32%, 38%, 30% and 17% of those with quiescent, mild, moderate and severe disease activity. Over time, the utility of CRP and ESR in reflecting disease activity remained stable in 70-80% of cases.
CONCLUSION: In ~2/3 of children, both CRP and ESR values reflect disease activity to a similar degree and in the remaining, either CRP or ESR may be sufficient, with slight superiority of CRP. CRP is more closely correlated with endoscopic appearance. When either CRP or ESR performs well for a given patient, this is likely to remain so over time. Therefore, it may not be justified to routinely test both ESR and CRP in monitoring disease activity.