Effect of Chewing Gum on Interdialytic Weight Gain, Thirst, Dry Mouth and Intradialytic Symptoms in Hemodialysis Patients: A Prospective Randomized Controlled Trial
Phase: NA
Conditions: Chewing Gum, Hemodialysis
Sponsor: Istanbul Demiroglu Bilim University

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Study Protocol 
Official title of the study: Effect of Chewing Gum in Hemodialysis Patients 
NCT number: NCT04142216 
Date of document: April 20, 2020 
 
Objective: The aim of this study was to investigate the effect of chewing gum on dry mouth, 
interdialytic weight gain (IWG) and intradialytic symptoms in hemodialysis (HD) patients. 
Design: Prospective, randomized controlled single-blind trial 
Methods: The study was conducted in accordance with the Declaration of Helsinki. 
Permission was obtained from the local ethics committee (Meeting Date: 07/16/2019, 
Decision No: 2019-7) and the relevant institutions in addition to written consent from the 
subjects. 
This study was conducted with patients treated at two HD units of two public hospitals 
between October 2019 and January 2020. Patients in the experimental group chewed gum for 
three months. The patients in the control group did not chew gum and there was no 
intervention. The 2010 CONSORT Statement for Randomized Trials of Non-Pharmacological 
Treatments was used as a guide to report the study. 
All the patients who had been treated for at least six months with sessions three days a 
week for four hours each, were aged 18 years or more, had no psychiatric disorder preventing 
communication, stated experiencing dry mouth, and volunteered to participate were included 
in the study. Patients who had previously received chemotherapy or radiotherapy; who had 
dementia, salivary gland infection, oral and/or dental discomfort that would prevent chewing 
gum; who were using antidepressants, antipsychotics, benzodiazepine or opioids; and who did 
not volunteer to participate were excluded. 
 

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Statistical Analysis Plan 
Official title of the study: Effect of Chewing Gum in Hemodialysis Patients 
NCT number: NCT04142216 
Date of document: April 20, 2020 
 
Outcome measures 
Primary outcomes 
Change from Baseline Intradialytic weight gain: Interdialytic weight gain was defined as 
the difference between the predialytic weight and weight at the end of the previous dialysis 
session. 
Change from Baseline Dry Mouth at three months: It will be assessed three times at the 
end of the dialysis session with Visual Analogue Scale. Visual Analogue Scale ranging from 0 
(no dry mouth) to 10 (worst dry mouth). Dry mouth increases the score increases. The high 
point describes bad outcome. 
Change from Baseline Dry Mouth at three months: It will be assessed three times at the 
end of the dialysis session with Visual Analogue Scale. Visual Analogue Scale ranging from 0 
(no dry mouth) to 10 (worst dry mouth). Dry mouth increases the score increases. The high 
point describes bad outcome. 
Change from Baseline Dry Mouth at three months: It will be assessed two times at the end 
of the dialysis session with sample of saliva. Saliva flow rate will be measured. Saliva flow 
rate is presented with "ml". 
Change from Baseline Intradialytic symptoms at three months: It will be assessed with 
"Dialysis Symptom Index". Using this scoring system, the minimum possible total severity 
score was 0 if none of the 30 symptoms was present and the maximum potential. Score was 

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150 if all of the 30 symptoms were reported and rated as “very much bothersome”. The 
minimum value is "0" and the maximum value is "150". 
Secondary outcomes 
Change from Baseline Anxiety at three months: It will be assessed with Hospital Anxiety and 
Depression Scale. This scale, which has a two-factor structure is comprised of 14 items. 
Seven of these items assess the anxiety status and the remaining seven assess depression. 
Each item is scored on a four-point scale. Total score ranges between 0 and 21 for anxiety and 
depression. Scores between 0 and 7 indicate normal emotional status. 
Change from Baseline Fluid Control at three months: It will be assessed with "Fluid 
Control Scale in Hemodialysis Patients". the scale had 24 items and three 
subdimensions,namely, knowledge, behavior, and attitude. The lowest score obtained from 
the scale was 24 and the highest score was 72, and the higher the score, the greater the 
compliance of the patients with fluid control. 
Change from Baseline Depression at three months: It will be assessed with Hospital 
Anxiety and Depression Scale. This scale, which has a two-factor structure is comprised of 14 
items. Seven of these items assess the anxiety status and the remaining seven assess 
depression. Each item is scored on a four-point scale. Total score ranges between 0 and 21 for 
anxiety and depression. Scores between 0 and 7 indicate normal emotional status. 
 
Statistical analysis 
The Statistical Package for Social Sciences (SPSS Inc., Chicago, IL., USA) 22.0 software 
program was used in the statistical analysis of the data obtained during the study. The 
compliance of the measurement values with a normal distribution was investigated with the 
“Shapiro-Wilk Test”. Mean±standard deviation, median, and interquartile range (IQR) were 
used to present the descriptive statistics of continuous numerical variables, and number (n) 

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and percentage (%) were used to present the categorical variables. Comparisons of the data 
not showing a normal distribution were made by using the “Mann-Whitney U Test”, “Chi-
Square Test”, and “Fisher’s Exact Test” while comparisons of the data showing a normal 
distribution were made using “Student’s t Test” and the “Paired Samples Test”. Variables 
measured at two different times in the dependent groups were compared with the “Wilcoxon 
Two-sample Paired Test”. The “Repeated-Measures Analysis of Variance” test was used to 
compare the measurements of the groups made at more than two different times. A p value 
<0·05 was considered statistically significant in statistical decisions. 
Results 
 
 

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