Autonomic and Inflammatory Markers Associated with Reduced Glomerular Filtration Rate in Non-Dialysis Chronic Kidney Disease: A Cross-Sectional Study

Abstract Background Chronic kidney disease (CKD) progression is influenced by metabolic comorbidities such as diabetes and hypertension and is frequently accompanied by impaired cardiovascular autonomic regulation. Although autonomic imbalance and systemic inflammation are both linked to adverse renal outcomes, their combined contribution to variability in estimated glomerular filtration rate (eGFR) in non-dialysis CKD patients remains unclear. This study aimed to evaluate whether autonomic function parameters and inflammatory markers are associated with eGFR beyond traditional clinical predictors. Methods This cross-sectional study included 43 patients with chronic kidney disease not receiving dialysis. Clinical data were obtained from medical records. Fasting blood samples were collected for creatinine, cystatin C, urea, and interleukin-6 measurements. eGFR was calculated using the combined creatinine–cystatin C equation. Heart rate variability (HRV) was recorded using a validated smartphone application and analyzed with Kubios HRV Scientific software. Blood pressure was measured with a digital sphygmomanometer. Results Interleukin-6 showed a significant negative correlation with eGFR. In contrast, most HRV parameters were not individually correlated with renal function. Multiple linear regression analysis explained 44.1% of the variance in eGFR. Although RMSSD (a parasympathetic index) alone did not independently predict eGFR after adjustment, the final multivariable model identified RMSSD, serum urea, and interleukin-6 as significant predictors alongside conventional variables such as body mass index and sex. Conclusion Parasympathetic modulation (RMSSD) and systemic inflammation (interleukin-6) are independently associated with renal function in non-dialysis CKD patients, suggesting that combining heart rate variability and inflammatory markers may improve clinical assessment and early risk stratification.