Common Terminology Criteria for Adverse Events (CTCAE) is a system used by clinicians to grade the toxicity of oncology treatments in a standardised manner. Dysphagia is perhaps the most common long-term toxicity of head and neck cancer treatment. Currently, a five-point scale is used based on patient reported symptoms, diet modification and tube dependence. However, this scale does not distinguish physiological impairment in swallowing. The authors propose a new toxicity scale that reflects a ‘true’ dysphagia determined by changes in physiology. It is based on assessing the key dimensions of swallowing safety (airway protection) and swallow efficiency (ease of bolus transit) as derived from a modified barium swallow (MBS). This new scale which they have termed DIGEST (Dynamic Imaging Grade of Swallowing Toxicity) maintains the simplicity of the original ordinal scale, but provides additional important information on dysphagia across the continuum of care. The CTCAE fails to differentiate acute changes in eating (due to pain, mucositis, thick secretions, nausea) from the more long-term impact of treatment (due to fibrosis, xerostomia, stricture, neuropathy) on swallowing function.
Not unexpectedly, only fair agreement between the CTCAE and DIGEST was observed in this study, highlighting that DIGEST complements CTCAE rather than duplicating information.
It improves specificity in the acute phase after oncology treatments (pharyngeal dysphagia versus other reasons for not eating) and specificity in the later stages (when no feeding tube does not mean no dysphagia). This paper is a useful read for those interested in measuring swallowing as an outcome in clinical trials.