Exploratory estimation of minimal clinically important deterioration in oral and swallowing function after oral cancer treatment: A prospective observational study.

OBJECTIVE: Oral cancer treatment frequently results in postoperative oral dysfunction, which may contribute to dysphagia, malnutrition, and impaired quality of life. Although objective and patient-reported oral/swallowing function measures are used in clinical practice, the minimal clinically important differences (MCIDs) corresponding to patient-perceived deterioration remain unclear. This study aimed to determine the MCIDs of objective and patient-reported oral/swallowing function measures associated with the oral health-related quality of life in patients with oral cancer. METHODS: This study included patients treated by an oral and maxillofacial surgery team at a tertiary university hospital from September 30, 2019, to December 31, 2025, and followed up at the end of the primary treatment. A total of 146 patients were evaluated before treatment and at discharge after primary therapy. Six oral function measures and the Geriatric Oral Health Assessment Index (GOHAI) were assessed, and anchor- and distribution-based methods were used to estimate the MCIDs. RESULTS: The total GOHAI scores decreased significantly. Multivariate analyses demonstrated that postoperative tongue pressure and EAT-10 scores were independently associated with GOHAI scores. Using a 3-point change in GOHAI as the primary anchor, estimated MCIDs were 0.5 for microorganisms, -3.05 for oral dryness, -321.6 N for occlusal force, -6.05 kPa for tongue pressure, -26.5 mg/dL for masticatory function, and 7.5 points for EAT-10. Distribution-based approaches yielded higher threshold values. CONCLUSION: These findings provide exploratory reference thresholds for interpreting clinically meaningful changes in oral and swallowing functions after oral cancer treatment and underscore the importance of MCID-based evaluation beyond statistical significance alone.