Effect of Applying Oral Hygiene Care on Swallowing in Stroke Patients With Oropharyngeal Dysphagia

Data collection:

• At trial baseline (Before oral hygiene intervention)

• 1.1. Socio-demographic data: age, gender, education, living conditions, and allowance for increased health care cost reimbursement
• 1.2. Medical information: smoking habit, medications, and medical background such as stroke type and location, stroke history, National Institutes of Health Stroke Scale (NIHSS), and Functional Oral Intake Scale (FOIS),
• 1.3. Dental information from oral examination:
• Oral care ability
• Oral hygiene index including dental plaque, tongue plaque, and denture plaque.
• Oral disease: Periodontal status and sign of periodontitis as tooth mobility, clinical dental caries, and clinical mucosal lesions.
• Oral status: the number of functional teeth, the number of posterior occluding pairs, and denture status
• Clinical oral dryness scoring
• 1.4. Tongue strength using maximum isometric pressure (MIP) from the Iowa Oral Performance Instrument (IOPI) during rest and swallowing stages
• 1.5. Test of Masticating and Swallowing Solids (TOMASS): number of discrete bites, number of masticatory cycles, number of swallows, and total time
• 1.6. Oral residue score (ORS)
• After oral hygiene intervention

• 2.1. Clinical measurements
• Modified TOMASS by using a half cracker: number of discrete bites, number of masticatory cycles, number of swallows, and total time
• Tongue strength using MIP from IOPI during rest and swallowing stages
• ORS
• 2.2. Subjective measurements: Visual Analogue Scale (VAS)

Sample size:

Sample size calculations were based on both the primary and secondary objectives, focusing on the primary outcomes: number of masticatory cycles, number of swallows, and total time.

For both objectives, sample size estimation was conducted using an independent t-test to compare means in a superiority test between two groups, with an alpha level of 0.05 and a power of 0.80. G*Power software (version 3.1.9.2, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany) was used for the calculation. The effect size for the intervention was estimated based on the standard deviation (SD) from pilot data, combined with the clinically relevant mean difference determined by the research team using pilot data and previous studies comparing individuals with dysphagia to healthy individuals.

The required sample size, calculated using the smallest effect size corresponding to total time in the primary and secondary objectives, was 53 and 62 participants per group, respectively. These calculations were based on an SD of 40.2 with a clinically relevant mean difference of 22 seconds for the primary objective, and an SD of 21.7 with a clinically relevant mean difference of 11 seconds for the secondary objective.

To account for a 5% dropout rate, the final sample size was adjusted to 65 participants per group, resulting in a total of 260 participants.

Randomization:

Randomization was conducted using a 1:1:1:1 allocation ratio with variable block sizes of 4 and 8, with sequences independently generated using Microsoft Excel version 16 (Microsoft, New Mexico, USA). Allocation and data collection were managed through REDCap (Research Electronic Data Capture), hosted at Ghent University Hospital.

Statistical methods:

The primary analysis will evaluate the superiority of the combined care group over the control group. If statistical significance is achieved, a secondary analysis will compare the combined care group with the mechanical oral hygiene and mouth moisturization groups, respectively.

An exploratory analysis using hierarchical pairwise comparisons will be conducted if both comparisons in the secondary analysis and the statistical analysis across all four groups show significance. The pairwise comparisons will be ordered sequentially, first comparing the mouth moisturization group with the control group, then the mechanical oral hygiene group with the control group and finally comparing the mouth moisturization and mechanical oral hygiene groups with each other.

All analyses will be performed using analysis of covariance (ANCOVA), with pre-intervention outcomes as covariates and a significance level of 0.05.

To address missing data, multiple imputation will be applied. Sensitivity analyses will compare results from imputed data with those from complete case analysis to ensure the robustness of findings.

Inclusion criteria

• Patients enrolled in the stroke unit at Ghent University and diagnosed with oropharyngeal dysphagia.
• Agreement to participate in the study and having signed an informed consent form.
• Age over 18 years.
• Sufficient cognitive abilities and language skills to understand the swallowing exercises.

Exclusion criteria

• A history of surgical intervention on the tongue.
• Edentulous individuals, both fully edentulous or edentulous in one dental arch, if they do not wear dentures.
• Patients with a penetration-aspiration scale (PAS) of 7 or 8 under flexible endoscopic evaluation of swallowing (FEES), at the international dysphagia diet standardisation initiative (IDDSI) level 7.
• Patients who cannot perform TOMASS, indicated by 25% or more of the amount of cracker's bolus that can be considered as the same cracker.