Response to the Letter by Chen et al. on “From Prognostic Marker to Therapeutic Target—Appetite in Swallowing Rehabilitation”

We appreciate the comments by Chen et al. [1] on our article [2]. In response, we provide further information and perspectives on these points. We are grateful for your positive appraisal of our use of the SNAQ-JE and our efforts to adjust for multiple clinical and functional confounders. You have raised several valid points that we agree are crucial for advancing future research in this field. First, you aptly noted that the relevance of rehabilitation intensity and nutritional intake to swallowing recovery. As you pointed out, both training dose and actual energy and protein intake are likely to confound or mediate the association between appetite and functional outcomes. Due to the retrospective single-center design of our study, standardized quantified data of rehabilitation frequency/duration or precise nutritional intake data were not consistently available across all participants. We fully agree that future prospective multicenter studies should systematically collect these variables, and we appreciate your specific suggestion to incorporate quantitative indicators of rehabilitation dose and nutritional adequacy. Second, we concur with you that appetite is a dynamic construct that may fluctuate during hospitalization in response to changes in disease status, psychological condition, oral discomfort, and medication use. Our study assessed appetite only at admission, which reflects routine practice in many rehabilitation settings but may not fully capture temporal variability and could have led to an underestimation or mischaracterization of its longitudinal impact. We support your proposal that repeated appetite assessments (e.g., at admission, mid-stay, and discharge), analyzed using time-dependent models, would provide a more accurate depiction of how appetite trajectories relate to swallowing recovery. Third, regarding your point that swallowing function measured at discharge can be influenced by length of stay and discharge destination, we acknowledge the potential for censoring bias. Although the length of stay did not differ significantly between appetite groups in our cohort, early transfer or discharge with feeding tubes can indeed affect the observed FILS at discharge. We agree that future studies should explicitly account for discharge timing and disposition, potentially utilizing time-to-event or competing-risk approaches. Fourth, you emphasized the importance of psychological status, oral health, and medication use (including polypharmacy). While we partially captured patient vulnerability through measures such as the MUST, sarcopenia, and functional independence, we lacked validated scales for depression or anxiety, detailed oral health assessments, and structured medication data. We acknowledge this limitation and agree that incorporating comprehensive geriatric assessments variables in future work would substantially reduce residual confounding and improve mechanistic understanding. Regarding statistical methodology, we appreciate your suggestion to use ordinal logistic regression or mixed-effects models. In the present study, we selected linear and logistic regression models primarily for interpretability and alignment with familiar clinical effect measures. However, we agree that ordinal and longitudinal modeling frameworks, as well as mediation analyses to explore pathways linking appetite and swallowing recovery, would be valuable in future prospective cohorts with larger samples. Finally, we wholeheartedly share your view that interventional research is needed. While our observational study cannot establish causality, your letter [1] thoughtfully outlines how targeted interventions, such as flavor modification, individualized nutritional support, psychological care, and oral management, might improve swallowing outcomes. Building on these constructive suggestions, we propose a future direction for advancing research on appetite and swallowing function. Appetite is influenced by a wide range of psychological and physical factors, and similarly, swallowing rehabilitation outcomes are shaped by numerous interacting variables. To conduct reproducible research that translates into meaningful improvements in swallowing function, systematic organization of these multifaceted factors is essential. Establishing a standardized framework for assessing and categorizing these determinants would serve as a critical prerequisite for high-quality multicenter studies and rigorous interventional trials. In summary, we greatly appreciate your insightful comments, which situate our work within a broader clinical context. We agree on the need for prospective, multicenter, and interventional studies that incorporate detailed data on rehabilitation, nutrition, and other unmeasured confounders. Continued dialogue in this area will help translate the concept of appetite from a screening variable into a practical lever for improving outcomes in older adults with swallowing disorders. The authors have nothing report. The authors declare no conflicts of interest. Research data are not shared.