We recruited 60 consecutive adult patients who had been referred to the Turku University Hospital phoniatrics outpatient clinic due to a complaint of dysphagia from primary health care or other medical disciplines. We excluded patients with severe cognitive or psychiatric illnesses or if they were unable to complete the questionnaires independently (writing assistance was accepted). Information on age, gender, body mass index (BMI), diagnosed diseases, previously performed surgeries, medication, smoking habits, and alcohol consumption were collected. We evaluated the etiology of dysphagia from medical records and examinations.

The patients filled in the Finnish version of the EAT-10 to provide their subjective evaluation of dysphagia symptoms and symptom severity. HRQoL was assessed using the 15D, and disability using the 36-item version of WHODAS 2.0 (self-administered). Each patient completed the questionnaires just before the outpatient appointment using a paper and pencil or did the web-based survey, provided by Research Electronic Data Capture (REDCap), according to their preference. For objective evaluation of dysphagia, we performed FEES and the simplified 100 ml Water Swallow test (sWST), in which only coughing and the number of swallows are observed [13, 14]. The patients filled in the follow-up questionnaires one month later. Reminders were emailed to them three times if they had not responded to the follow-up questionnaires after one month.

The 10-item Eating Assessment Tool (EAT-10) is one of the most widely used tools for evaluating dysphagia [10]. It has been translated into multiple languages, including Finnish, and validated across diverse populations. Currently, it is distributed by the Nestlé Nutrition Institute (© Société des Produits Nestlé SA 2009). EAT-10 comprises ten items, each rated on a five-point Likert scale, ranging from no difficulty (0 points) to severe difficulty (4 points). The total score is calculated as the sum score of all item scores, producing a range of 0 to 40 [10]. For this study, we used the Finnish version of the EAT-10 [6]. In the one-month follow-up EAT-10 questionnaire, we added an item to assess subjective symptom changes over the past 30 days, scored as follows: 0 = no symptoms, 1 = fewer symptoms, 2 = symptoms unchanged, 3 = slightly more symptoms, 4 = many more symptoms.

The 15D is a generic, patient-reported measure of HRQoL, covering15 dimensions: mobility, vision, hearing, breathing, sleeping, eating, speech, excretion, usual activities, mental function, discomfort and symptoms, depression, distress, vitality, and sexual activity [11]. Each dimension is rated on a five-point Likert scale, where 1 represents the best possible situation and 5 the worst. A single index score, or 15D score, is calculated to represent overall HRQoL on a 0–1 scale, with 1 indicating full health and 0 representing death. Dimension-specific scores, reflecting levels from no problems (= 1) to death(= 0), are derived from population-based utility weights. Mean scores for each dimension are used to draw 15D profiles for groups [11]. The minimal clinically important difference in the overall 15D score is reported as 0.015 [15]. Normative values, matched by age and gender, were obtained from the Finnish National Health 2011 Survey [16].

In dysphagia research, the 15D has previously been used only with specific patient groups, including those with dysphagia following cervical anterior decompression surgery and patients experiencing globus symptoms [17, 18].

WHODAS 2.0, developed by the World Health Organization (WHO), is a standardized tool for measuring health and disability across six life domains: (1) cognition, (2) mobility, (3) self-care, (4) getting along, (5.1) life activities, (5.2) work and studying, and 6) participation [12]. There are three versions of WHODAS 2.0: a 36-item version, a12-item version, and a 12 + 24 item version, with the 36-item version providing the most detailed assessment. Each item is rated on a five-point Likert scale, (none = 0, mild = 1, moderate = 2, severe = 3, and extreme = 4), with scores summed by domain and overall for a total simple score. Complex scoring, based on item-response theory, weights and codes each item to produce domain scores and a total score on a 0–100 scale, where 0 represents no disability and 100 represents full disability [12].

In this study, we used the Finnish 36-item, self-administered version of WHODAS 2.0 [19]. Simple scoring was applied to compare baseline and one-month follow-up results, while complex scoring was used to benchmark the patient cohort against normative values from the Swedish population, as Finnish population norms for WHODAS 2.0 are not yet available [20]. Given Sweden’s close geographic and cultural proximity as a fellow Nordic country, Swedish norms are assumed to approximate Finnish values.

WHODAS 2.0 is widely applicable across diagnostic groups, particularly in psychiatry, geriatrics, neurology, disability and rehabilitation, health sciences, and epidemiology [21]. In dysphagia research, WHODAS 2.0 has been used to assess disability among survivors of head and neck cancer and patients with corrosive esophageal stricture [22, 23].

The outpatient appointments at Turku University Hospital Phoniatrics Clinic lasted 90 min. with both a physician (specialist in otolaryngology and phoniatrics) and a speech-language pathologist (SLP) present. The patient was interviewed, and the FEES was performed. Before evaluating swallowing, the physician and the SLP jointly assessed velopharyngeal closure, rated possible saliva residues in the vallecula and pyriform sinuses, and evaluated tongue movement, pharyngeal wall movement, and vocal cord closure. The boluses were dyed with food coloring for better visualization, and the textures used in the FEES included liquid (water), nectar (blueberry soup), semi-solid (fruit puree), and solid (cookie). The examination began with small boluses (half a teaspoon) and progressed to larger ones (a tablespoon). Pharyngeal residues were scored using the Yale Pharyngeal Residue Severity Scale [24], while possible penetration or aspiration was assessed using the Penetration-Aspiration Scale (PAS) [25], and the Dysphagia Outcome Severity Scale (DOSS) was used for final evaluation [26].

After the FEES, we used the simplified version of the 100 ml Water Swallow Test (sWST), in which the patient is asked to drink 100 ml of water continuously. They passed the test if they did not stop their drinking, did not cough while drinking or one minute after drinking, and were able to finish the 100 ml in less than five swallows [14].

After the examination, the physician showed the FEES recordings to the patient and explained swallowing anatomy and physiology using illustrations if needed. Any disturbances in swallowing were highlighted in the videos. The most bothersome symptom was identified, and possible factors interfering with normal swallowing were detected. Facilitating factors for swallowing were also identified and explained. The patients were advised to avoid any potential avoidance behaviors, and normal, social eating was encouraged, provided no safety risks were observed during the swallowing examination. Any fears, anxieties, or distorted thoughts about swallowing were addressed, and both the physician and the SLP worked to alleviate them. Instructions were given to humidify and lubricate the nose and throat if mucosal dryness was identified. Instructions to modify swallowing speed, bolus size and/or consistency were also provided if necessary. Postural changes or swallowing maneuvers, such as the supraglottic swallow or effortful swallow, were introduced with the FEES biofeedback if considered potentially effective. If needed, chewing muscle or head and neck massage was recommended, along with instructions for self-treatment to alleviate muscle tightness. Swallowing exercises or techniques such as thermal or electrical stimulation were not included. All instructions were also provided to the patients in written form. This type of intervention is called swallowing guidance, which differs from swallowing therapy.

The etiology of dysphagia was determined based on findings from the outpatient appointment and any additional assessments, such as neurology consultations, videofluoroscopy, or esophageal examinations (including esophagogastroscopy, multichannel intraluminal impedance and pH monitoring, or high-resolution manometry). We categorized dysphagia etiologies into the following groups: functional, globus, dry mouth/throat, neurological, esophageal (reflux, motility disorder, esophagitis), compression (e.g., cervical osteophyte), presbyphagia, and head and neck or esophageal cancer. Functional dysphagia is defined as swallowing difficulty without a structural, neurological, or other identifiable physical cause in the digestive tract.

For the FEES, we used a 3.9 mm–2.6 mm videoendoscope (Olympus HD ENF-VH or -V3), an Olympus Evis Exera III HDTV video processor CV-190 and CLL-S1 light source, (Olympus Europa, Hamburg, Germany). All the recordings were made by the rpSzene Software (rpSzene, Rheder, Hamburg, Germany).

Before participating, the recruited patients received both verbal and written information about the study and were asked to provide their written consent to participation. The Ethics Committee of the Hospital District of Southwest Finland approved the study protocol, and permission for the research was obtained from the same district. This study was carried out in compliance with the principles outlined in the Declaration of Helsinki (The World Medical Association 2013).

The sample size was determined by estimating various means and standard deviations (SD) for changes in the EAT-10 total score between baseline and one-month follow-up, using the Wilcoxon Signed Rank Test. Assuming an expected decrease of two points in the EAT-10 total score, a sample size of 54 participants was calculated. With an anticipated 10% dropout rate, the required sample size was set at 60 participants.

HRQoL was assessed by comparing baseline 15D scores to an age- and gender-matched sample from the general Finnish population, with differences evaluated using an independent samples t-test. One-way ANOVA with Bonferroni corrections was used to post hoc comparison of 15D means between different diagnostic groups. Differences in WHODAS 2.0 domain scores and total scores between the initial appointment and the one-month follow-up were analyzed with the Wilcoxon Signed Rank Test. Correlation between age and EAT-10 total scores was assessed with Spearman’s rho. The effect of gender on EAT-10 scores was tested with the Mann-Whitney U test, while the impact on subjective symptom change was evaluated using the Chi-square test. Differences in age and gender distribution between participants who returned follow-up questionnaires and those who did not were also assessed using the Mann-Whitney U test and the Chi-square test, respectively. P-values < 0.05 were considered statistically significant.

We consulted an experienced statistician for the statistical analyses, performed with the IBM SPSS Statistics for Windows (version 29.0; IBM Corp., Armonk, NY, USA).