In the past, criteria for the diagnosis and grading of the severity of esophageal mucosal consequences of gastroesophageal reflux disease (GERD) have been postulated with insufficient consultation and critical evaluation. The result has been a confusion of inadequately defined criteria, which impairs the quality of communication about endoscopic findings in both routine patient care and research studies. Endoscopists were unable to recognize these changes with acceptable agreement. The result was a lack of consensus on how to assess the presence and extent of CLE in clinical practice. The grading systems which have been proposed previously include:
The classification of CLE into long (≥ 3 cm) and short (<3 cm) segments: this system seems clinically irreverent because it was documented that even SSBE may undergo progression to dysplasia as well as adenocarcinoma.[4-7]
The Z-line appearance (ZAP) classification: this was developed to describe the endoscopic extent of CLE with particular reference to SSBE. The ZAP was found to correlate with the prevalence of IM at the SCJ; however, this system also uses a threshold of 3 cm to distinguish between grades II and III CLE making it insufficiently precise for documenting progression or regression of CLE.
Several years of research and deliberations by the International Working Group For The Classification Of Esophagitis (IWGCO) have led to the development and validation of explicit, consensus-driven criteria for the endoscopic diagnosis and grading of CLE called the Prague C & M Criteria for CLE (Fig. 1). The Prague C & M Criteria is a new grading system for CLE, and it was so named because it was first introduced by the IWGCO at the 11th United European Gastroenterology Week meeting in Prague, Czech Republic in 2004. The purpose of these criteria is to simplify and standardize endoscopic characterization of the extent and length of CLE. The new system emphasizes the use of esophageal landmarks to assess the circumference (C) and maximal (M) extent of the endoscopically visualized CLE segment. The key steps in Prague C & M Criteria are: (i) identify the GEJ as at the tops of the gastric mucosal folds; if hiatus hernia is present, do not confuse with the diaphragmatic hiatal impression for the GEJ; (ii) for circumferential columnar-appearing mucosa above the GEJ, define this extent in centimeters above the GEJ: report as the C-value; and (iii) for any tongue-like areas of columnar-appearing mucosa, measure the maximum extent in centimeters above the GEJ: report as the M-value. The primary validation study for these criteria was published by Sharma et al. in November 2006. The criteria are simple, reliable, reproducible and memorable. It is expected to be a practical clinical tool for characterizing the severity of CLE and for evaluating its progression over time. Now there is a need to build experience in the use of these criteria. As there is no widely used method of grading CLE currently, the Prague C & M Criteria are expected to be used worldwide. The most important weakness of this grading system appears to be in patients with short segment CLE. The kappa measures of interobserver agreement fell markedly when the length of tissue involvement was less than 1 cm.
Prague C & M Criteria for Endoscopically Suspected Esophageal Columnar Metaplasia/Barrett's Esophagus. (Reproduced with permission from the International Working Group for the Classification of Oesophagitis (IWGCO) http://www.iwgco.com )