Neurogenic dysphagia as an independent driver of hospital length of stay and costs: a Bayesian analysis with geriatric stratification and intervention simulation

Purpose: Neurogenic dysphagia is prevalent in neurological inpatients and associated with adverse outcomes, yet its independent economic impact after adjustment for frailty and functional status remains poorly quantified. We aimed to estimate the independent effect of dysphagia on hospital length of stay (LOS) and costs, to test whether this effect differs between geriatric and non-geriatric patients, and to quantify the probability and magnitude of cost savings from improvements in swallowing function. Methods: We analysed 10,375 neurological inpatient cases (2021-2024) at a German university hospital. Dysphagia was defined by fiberoptic endoscopic evaluation of swallowing (FEES) or ICD-10 R13 coding (n = 1,382; 13.3%). Bayesian Gamma-log regression with informative priors from historical data and published literature was used to model LOS and total case costs (German DRG), adjusted for age, sex, Hospital Frailty Risk Score (HFRS, R13-adjusted), self-care index ("Selbstpflege-Index", SPI), stroke status, and emergency admission. A geriatric cohort was defined as age >=70 and adjusted HFRS >=5 (n = 2,053; 19.8%). Posterior predictive simulation estimated cost savings for hypothetical improvements of 1-3 points on the Functional Oral Intake Scale (FOIS). Results: After comprehensive adjustment, dysphagia was independently associated with 46.5% longer LOS (posterior ratio 1.465; 95% credible interval [CrI] 1.397-1.537) and 28.2% higher total case costs (ratio 1.282; CrI 1.213-1.354). The dysphagia x geriatric interaction was small but credible and ran in opposite directions: slightly attenuated for LOS (interaction ratio 0.908, CrI 0.837-0.986) but slightly amplified for costs (1.096, CrI 1.012-1.185), consistent with complexity-driven DRG grouping in geriatric patients. The absolute economic burden remained larger in the geriatric cohort due to higher baseline costs. In the geriatric cohort, a one-point FOIS improvement yielded a 74.3% posterior probability of LOS-based savings (mean EUR 555/case); at three points, this rose to 84.2% (mean EUR 1,115/case). The direct cost model confirmed high benefit probabilities from the payer's perspective (82.6% at dFOIS = 3). Conclusions: Neurogenic dysphagia is an independent and substantial driver of hospital LOS and costs in neurological inpatients, even after adjustment for frailty and functional status. The proportional effect on costs is slightly larger in geriatric patients, while the LOS effect is slightly smaller, consistent with the mechanics of the G-DRG system. Bayesian simulation indicates that improvements in swallowing function carry a high probability of generating cost savings, supporting the characterisation of dysphagia as a modifiable economic target with particular relevance to geriatric neurology.