Prevalence of Intradialytic Hypertension Among Patients Undergoing Maintenance Hemodialysis: A Single-Center Cross-Sectional Study Using Three Diagnostic Definitions

Technical Summary: Prevalence of Intradialytic Hypertension Among Patients Undergoing Maintenance Hemodialysis

Problem Statement
Intradialytic hypertension (IDH) is characterized by a paradoxical increase in blood pressure during or immediately after hemodialysis, a phenomenon linked to adverse cardiovascular outcomes. However, the reported prevalence of IDH varies substantially across the literature due to the absence of a universally applied diagnostic definition. Existing studies utilize heterogeneous criteria, ranging from any intradialytic rise to specific absolute increases in systolic blood pressure (SBP) or post-dialysis hypertensive thresholds. This definitional inconsistency complicates case ascertainment, prevalence estimation, and clinical interpretation, particularly in single-center descriptive studies where comparisons with external populations may be misleading.

Methodology
This single-center, cross-sectional study was conducted at the maintenance hemodialysis unit of Kasturba Medical College, Mangalore, India, between January and July 2026. The analytic cohort consisted of 280 adults (mean age 49.5 ± 14.6 years; 60% male) with end-stage kidney disease undergoing maintenance hemodialysis for at least three months.

The study evaluated pre- and post-dialysis systolic blood pressure (SBP) over six consecutive sessions using automated monitors integrated into Fresenius dialysis machines. To address the variability in diagnostic criteria, the author applied three distinct, reproducible operational definitions to the dataset:

• Definition A (Recurrent Any-Rise): Post-dialysis SBP exceeded pre-dialysis SBP in at least four of six sessions.
• Definition B (Recurrent Significant Rise): Post-dialysis SBP increased by ≥10 mmHg compared to pre-dialysis SBP in at least four of six sessions.
• Definition C (Recurrent Hypertensive-Range Rise): Criteria for Definition B were met, and the post-dialysis SBP was ≥140 mmHg in at least four of six sessions.

Statistical analysis included the calculation of prevalence with Wilson 95% confidence intervals (CIs) and the assessment of agreement between definitions using Cohen's kappa. Unadjusted subgroup analyses were performed for sex and diabetes status using Pearson's chi-square test.

Key Results

• Blood Pressure Trajectories: The mean session-averaged SBP increased from 138.7 ± 7.6 mmHg pre-dialysis to 146.1 ± 12.1 mmHg post-dialysis, representing a mean change of +7.4 ± 7.6 mmHg.
• Prevalence Estimates:
  • Definitions A and B yielded identical prevalence rates of 69.6% (195/280; 95% CI 64.0–74.7).
  • Definition C, which included the hypertensive-range threshold, identified 60.0% (168/280; 95% CI 54.2–65.6) of participants.
  • The inclusion of the post-dialysis SBP ≥140 mmHg criterion resulted in an absolute reduction of 9.6 percentage points in prevalence.
• Agreement: Definitions A and B showed perfect agreement (κ = 1.00). Both definitions agreed with Definition C in 90.4% of participants (κ = 0.79). The 27 participants who met Definitions A and B but not C had recurrent rises ≥10 mmHg but failed to reach the post-dialysis hypertensive threshold.
• Subgroup Associations: Unadjusted analyses revealed stark differences in prevalence by sex and diabetes status. Under Definition A, prevalence was 96.4% in males versus 29.5% in females, and 98.2% in participants with diabetes versus 50.6% in those without. Similar patterns were observed under Definition C.

Key Contributions

1. Quantification of Definitional Impact: The study demonstrates that the operational definition used significantly alters prevalence estimates. Specifically, requiring a post-dialysis SBP in the hypertensive range (Definition C) excludes approximately one in ten patients who otherwise exhibit recurrent significant intradialytic rises.
2. Data Polarization: The analysis revealed that in this specific dataset, Definitions A and B were identical, suggesting a polarized distribution of blood pressure trajectories where patients either exhibited minimal change or a rise of ≥10 mmHg.
3. Methodological Transparency: By reporting prevalence across three distinct definitions and quantifying their agreement, the study highlights the necessity of precise operational criteria for valid clinical interpretation and cross-study comparability.

Significance and Claims
The paper asserts that while the estimated IDH prevalence in this cohort is high (ranging from 60.0% to 69.6%), these figures must be interpreted with caution. The author explicitly notes that the dataset exhibited "extensive exact repetition" of blood pressure trajectories (only 25 unique six-session trajectories among 280 records), which may indicate structured data generation or templating.

Consequently, the author concludes that these findings should be regarded as provisional. They emphasize that before these estimates can support clinical or epidemiological conclusions, the source data must be reconciled against original records, and clinical method details must be completed. The study underscores that while explicit definition reporting improves comparability, the validity of the prevalence estimates is contingent upon the verification of the underlying data integrity. The author refrains from drawing causal inferences regarding the strong unadjusted associations with male sex and diabetes, citing the lack of multivariable adjustment and the potential for confounding.