Spontaneous All-Sequence Baroreflex Sensitivity Across Predialysis Chronic Kidney Disease Categories: A Cross-Sectional Study.

Introduction Cardiovascular autonomic dysfunction contributes to the excess cardiovascular burden of chronic kidney disease (CKD). Spontaneous baroreflex sensitivity (BRS) quantifies the cardiac interval response to short-term changes in systolic blood pressure (SBP); however, balanced comparisons across consecutive predialysis CKD categories remain limited. Materials and methods This cross-sectional observational study was conducted from May 2024 to October 2025 in the Autonomic and Vascular Function Testing Laboratory, Department of Physiology, Indira Gandhi Institute of Medical Sciences (IGIMS), Patna, in collaboration with the Department of Nephrology. It used stage-stratified consecutive sampling to recruit 162 adults aged 18-65 years with predialysis CKD, with 54 participants in each of the G3, G4, and G5 categories. After 10 minutes of supine rest, a continuous five-minute stationary segment of simultaneous electrocardiographic and beat-to-beat arterial pressure signals was analyzed. Spontaneous all-sequence BRS was calculated using Nevrokard BRS version 6.3.0 (Nevrokard Kiauta, Izola, Slovenia). Category differences were assessed using Welch analysis of variance with Games-Howell pairwise comparisons. A post hoc multivariable linear regression sensitivity analysis using HC3 robust standard errors was performed to adjust for age, sex, body mass index (BMI), and resting SBP. Results The mean BRS was 10.87 ± 5.02 ms/mmHg in G3, 7.05 ± 3.39 ms/mmHg in G4, and 3.44 ± 1.86 ms/mmHg in G5. The overall difference was significant (p < 0.001), and all pairwise comparisons remained significant after adjustment for multiple comparisons. In an exploratory multivariable sensitivity analysis, BRS remained significantly lower in G4 and G5 compared with G3 after adjustment for age, sex, BMI, and resting SBP. Conclusions Spontaneous all-sequence BRS was substantially lower across successively higher predialysis CKD categories, and the association persisted after adjustment for age, sex, BMI, and resting SBP. However, the cross-sectional design does not establish temporal progression, causality, or prognostic utility.