Supplementary Material for: Monthly versus bimonthly bioelectrical impedance analysis for dry weight assessment and intradialytic hypotension: a randomized crossover trial

Background: Intradialytic hypotension (IDH) is a major complication during hemodialysis, leading to arrhythmias and increased mortality. Inaccurate dry weight (DW) adjustment contributes to IDH. Bioelectrical impedance analysis (BIA) is commonly used to assess body composition, including fluid compartments, aiding in DW measurement. However, the measurement intreval of BIA measurement to reduce IDH remains unclear.
Methods: This single-center, randomized crossover trial enrolled 94 end-stage kidney disease (ESKD) patients on hemodialysis, and 82 of them completed the protocol. Participants were divided into two groups: Group 1 underwent BIA monthly for four months, then bimonthly twice; Group 2 started with BIA bimonthly twice, then monthly for four months. A one-month washout period was implemented before switching measurement frequencies. The primary outcome was to determine if bimonthly BIA reduced IDH as effectively as monthly BIA. Secondary outcomes assessed factors influencing IDH.
Results: No significant different incidence rate of IDH between monthly and bimonthly BIA measurement frequencies in both per-protocol (0.044 and 0.046 per patient-treatment, respectively. p = 0.85) and as-treated (0.043 and 0.050 per patient-treatment, respectively. p = 0.59) analyses. Factors increasing IDH risk included older age, comorbidities including diabetes, dyslipidemia, and ischemic heart disease, elevated pre-dialysis blood pressure, and high net ultrafiltration. Additionally, lower hemoglobin, sodium, and albumin levels significantly elevated IDH incidence.
Conclusion: There was no significant difference in the incidence rate of IDH between monthly and bimonthly BIA measurements.