2023 Impact Factor
The recently published Chicago classification version 4.0 (CCv4.0) standardizes the protocol for performing high-resolution manometry (HRM) and provides a more sophisticated diagnostic flow for esophageal motility disorders compared to version 3.0.1 Major differences between CCv4.0 and its predecessor include the requirement for testing in both supine and upright positions, the inclusion of provocation tests such as multiple rapid swallows and rapid drink challenge (RDC), and the use of supportive tests such as functional luminal imaging probe (FLIP) and timed barium esophagogram for ambiguous diagnoses. CCv4.0 also suggests different integrated relaxation pressure (IRP) reference values based on equipment type and position. The updated diagnostic criteria have become more stringent, particularly for esophagogastric junction outflow obstruction (EGJOO). These revisions aim to establish consistency in testing protocols, enhance diagnostic reliability, and minimize inconclusive or ambiguous diagnoses, thereby increasing the number of patients who receive appropriate treatment.
The article by Wang et al2 investigates the clinical diagnostic efficacy of the RDC provocation test when added to the standard protocol in CCv4.0. This provocation test challenges the esophagus through continuous liquid ingestion, capturing the dynamic responses of the esophageal body and lower esophageal sphincter, allowing for a more comprehensive assessment of esophageal motility disorders.3 The results of the study found that adding RDC to the diagnostic flow increased diagnostic yield by 1.99%. However, it also revealed a significant issue with a 17.93% failure rate for RDC. This conflicting outcome highlights the need for careful interpretation and application of RDC results and provides insight into the practical implications of implementing CCv4.0 in clinical settings. Despite the modest increase in diagnostic efficiency, the high failure rate suggests the need for a personalized approach and tailored diagnostic strategies in diagnosing esophageal motility disorders. Notably, a significant proportion of patients in the RDC failure group were diagnosed with achalasia, indicating that RDC may not be effective for all diagnoses. This suggests that additional tests, such as FLIP or timed barium esophagogram, may be important for a comprehensive evaluation of esophageal motility disorders.
The study estimated the diagnostic cutoff value for RDC-integrated relaxation pressure (RDC-IRP) as 19 mmHg based on receiver operating characteristic analysis of FLIP data from the Diversatek system. Previous studies using the Medtronic system have reported cutoff values for RDC-IRP ranging from 8 mmHg to 16.7 mmHg.4-6 These differences could be attributed to variations in technology and patient demographics, such as age,7,8 and they highlight potential inconsistencies between different HRM systems.
The study also showed that many diagnoses of EGJOO made under CC v3.0 were revised with CC v4.0. While CC v4.0 improves the diagnostic process,9-12 further validation of RDC in various clinical settings, along with the standardization of diagnostic values across HRM systems, may be necessary.
Future research should explore the clinical implications of RDC failures and the variations in diagnostic cutoff values. Validating cutoff values across different HRM systems and assessing the broader applicability of RDC within CCv4.0 will be essential. Collaborative efforts and standardization for HRM protocol will be crucial for enhancing diagnostic reliability and providing effective treatment for patients with of esophageal motility disorders.
In conclusion, while CCv4.0 represents a significant advancement in the field, this study emphasizes the need for ongoing evaluation and refinement of diagnostic tools such as RDC. Addressing these challenges will improve diagnostic accuracy and ensure optimal treatment for patients with esophageal motility disorders.
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