The Feasibility and Safety of an Intradialytic Exercise Program: DIALY-SIZE

Recruitment: participants will be recruited by a study coordinator during their regular hemodialysis shift. This is a quaternary outpatient dialysis unit serving approximately 110 patients.

Randomization and allocation: we will use a permuted block design with randomly varied block sizes of eight and twelve. The randomization sequence will be computer generated and randomization to one of the 4 groups will be on a 1:1:1:1 ratio. Allocation is concealed in serially numbered, opaque, sealed envelopes.

Data collection: demographic data, length of time of hemodialysis, cause of ESRD, access type, comorbidities, number of medications, functional status, comorbidities, and dialysis prescription will be collected. The laboratory values and dialysis prescription will be collected from the dialysis unit chart using the most recent monthly blood-work and from the provincial laboratory repository. The amount and intensity of exercise that was performed as well as the participant's heart rate and blood pressure during the exercise session will be recorded at each exercise session. The exercise forms from each participant's dialysis session will be reviewed weekly for missing data. Forms with any empty field will be classified as incomplete and where possible, the appropriate staff will be asked to verify the query.

The occurrence of adverse events will be collected from all four randomization groups.The hemodialysis run-sheet, nursing notes, and exercise data collection form will be reviewed weekly for the occurence of adverse events. Hemodialysis unit staff and the exercise trainer have been instructed to report adverse events (defined a priori) as they occur. In addition, prior to each exercise session, participants will be asked if they have had any new health problems or symptoms since their last exercise session.

Missing data: conditional on the participant's consent, outcome data will be collected from all participants who drop out. For those participants who do not wish to be followed or who have missing data, baseline data will be carried forward.

Safety: due to the short duration and small size of this study, a formal safety and trial management board will not be established. A nephrologist who is not affiliated with the study will review all SAEs as they occur. The nephrologist will then determine if the SAE was associated with the intervention and whether the individual's participation requires modification or discontinuation.

Statistical analysis plan: descriptive statistics will be used to compare the clinical characteristics of the four groups at baseline. All analyses will follow the intention to treat principle.

Safety: in a primary analysis, adverse events will be reported as the number of events directly related to the intervention compared to control, by randomization group. In a secondary analysis, all adverse events that occurred during the study will be analyzed. The frequency of events will be compared using ANOVA or Kruskal-Wallis where appropriate, and with appropriate post-hoc tests to detect differences between randomization groups.

To explore the effect of aerobic and resistance exercise on components of HRQOL we will estimate the absolute change in score at 12 weeks relative to baseline in the physical component summary score (PCS), the mental component summary score (MCS), and the kidney-disease specific score (KDCS). We will report the absolute change in sub-scores for each of the component summary scores. We will use the same method to estimate the difference in scores on the tests of physical performance and strength. Assuming there is no statistical interaction (no indication in the literature), we will estimate the efficacy of the aerobic intervention by comparing all participants who received aerobic exercise with all groups that did not (aerobic and combined exercise groups versus resistance and control exercise groups) and similarly for the resistance-training group. Final scores will be compared using analysis of covariance (ANCOVA) adjusting for the baseline scores and both main effect terms. The final score will be presented as the adjusted difference in the means. To correct for multiple comparisons in the combined exercise group, based on the Bonferroni procedure a significance level of less than 0.025 will be considered significant. The same method will be used to analyze differences in the tests of physical functioning and strength. The interaction will be estimated in a secondary analysis. Due to the small sample size, no subgroup analysis will be performed.

Inclusion criteria

• adult (age ≥18)
• dialysis dependent for ≥ 3 consecutive months
• receiving ≥ 3 dialysis treatments per week
• mobile (any distance and can be with the assistance of an aid)
• at least one non-prosthetic and functional limb
• stable during hemodialysis treatment (assessed by hemodialysis unit staff and the study physician)
• capable of providing consent

Exclusion criteria

• currently enrolled in a clinical trial
• missing an average of more than 2 shifts per month
• planned move or modality change within the next 4 months
• currently enrolled in a structured exercise program
• scheduled hospitalization for > 1 week
• any uncontrolled medical condition that would preclude participation in a low/moderate intensity exercise program (e.g. unstable angina, uncontrolled hypertension, severe valvular heart disease)