Plateletcrit: a sensitive biomarker for evaluating disease activity in Crohn's disease with low hs-CRP.

Objective: This study aimed to investigate whether PLT indices could act as non-invasive biomarkers for active Crohn's disease (CD).

Methods: Altogether 130 CD patients and 130 age- and gender-matched healthy volunteers were retrospectively enrolled in the study. CD patients were further divided into patients with active disease (Crohn's disease activity index [CDAI] >150) and in remission. PLT indices including PLT count, mean platelet volume (MPV), platelet distribution width (PDW), platelet large cell ratio (P-LCR) and plateletcrit (PCT) were detected. High-sensitivity C-reactive protein (hs-CRP) and erythrocyte sedimentation rate (ESR) levels were also determined.

Results: In active CD, PLT and PCT levels were notably higher but P-LCR and PDW levels were lower than those in healthy controls and patients in remission. PLT, PDW, P-LCR and PCT were significantly correlated with CDAI (P < 0.05). The receiver operating characteristic (ROC) curve showed that with a cut-off value of 0.28%, PCT achieved a sensitivity of 67% and a specificity of 63% for detecting active CD, with the area under ROC curve (AUROC) of 0.67, which was inferior to hs-CRP and ESR. For patients with active disease who had hs-CRP levels lower than 10.0 mg/L, PCT turned out to be the best index for monitoring disease activity (sensitivity 71%, specificity 85%, AUROC 0.77, P = 0.02).

Conclusion: PCT may act as a specific and sensitive biomarker for determining active CD, especially in patients with an hs-CRP level lower than 10.0 mg/L.