PICaSSO Endoscopic Score

PICaSSO Endoscopic Score

March 15, 2021

Issue 05

Clinical Question

What is the clinical utility of virtual chromoendoscopy using the PICaSSO endoscopic score?

Editor’s Bottom Line

Virtual chromoendoscopy for ulcerative colitis is accessible, correlates with histology when scored using PICaSSO, and provides useful prognostic information.


Iacucci M, Smith SCL, Bazarova A, et al. An International Multicenter Real-Life Prospective Study of Electronic Chromoendoscopy Score PICaSSO in Ulcerative Colitis. Gastroenterol. Epub ahead of print Feb 6, 2021; https://doi.org/10.1053/j.gastro.2020.12.024


Researchers at 11 centers in Europe and North America prospectively analyzed data from 307 colonoscopies performed in adult patients with ulcerative colitis. They evaluated rectal and sigmoid colon inflammation using the Paddington International Virtual ChromoendoScopy ScOre (PICaSSO), which assesses the vascular and mucosal features of healing, as well as the Mayo Endoscopic Score (MES) and the Ulcerative Colitis Endoscopic Index of Severity (UCEIS). Pathologists evaluated targeted biopsies using five established histological scoring systems and clinical activity was assessed 6 and 12 months after colonoscopy

The authors performed statistical analyses to document correlations between the three endoscopic scores as well as with histologic scores and clinical outcomes at follow-up.

Findings showed that strong interobserver agreement for PICaSSO scoring (1-way intraclass coefficient (ICC): 0.88; 95% CI, 0.83–0.92) and strong correlation between PICaSSO values and scores on the MES and UCEIS (Pearson correlation: 0.8–0.93).

While all endoscopy scores correlated well with histology scores, PICaSSO scores correlated most strongly (Pearson correlation: 0.76–0.79 for PICaSSO vs. 0.68–0.73 for MES and 0.71–0.74 for UCEIS). Additionally, a PICaSSO value ≤3 was strongly correlated with histologic remission as measured by the Robarts Histopathological Index (RHI) (Area Under the Receiver Operating Characteristic Curve (AUROC): 0.90; 95% Confidence Interval [CI], 0.86–0.94) and the Nancy Histological Index (NHI) (AUROC: 0.82; 95% CI, 0.77–0.87).

A PICaSSO score ≤3 was as accurate as histological remission in predicting clinical outcomes at 6 and 12 months.


Study Design: Prospective cohort

Funding: NIHR Birmingham Biomedical Research Centre

Allocation: None

Setting: Multicenter

Level of Evidence: 1b