The relationship between intradialytic BP variability (BPV) and mild cognitive impairment (MCI) in maintenance hemo-dialysis (MHD) is unclear, but new research published in BMC Nephrology examines their correlation.

For the retrospective study, researchers collected intradialytic systolic BP (SBP) measurements 3 months before cognitive assessment as baseline data and averaged them as final data. They converted SBP into 4 BPV indices: standard deviation, coefficient of variation, average real variability (ARV), and RANGE. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA) scale. Based on the MoCA score, patients were assigned to the MCI group (MoCA score <26) and the non-MCI group (MoCA score ≥26).

A total of 170 patients with 6,662 dialysis records and 26,580 SBP measurements were enrolled. The MCI group included 133 patients, and the non-MCI group included 37 patients. Overall, the mean age was 59.99 years, 58.24% of patients were men, and the prevalence of MCI was 78.24%. Patients in the MCI group were older with a higher percentage of diabetes.

High SBP ARV Closely Associated With MCI

Intradialytic SBP ARV was noticeably higher in the MCI group compared with the non-MCI group (8.91 vs 7.60, respectively; P=0.042), and the mean SBV and other SBV indices between the two groups showed no notable difference. The researchers found that a nonlinear relationship existed between SBP ARV and MCI, with an inflection point of 7.52.

The univariate logistic analysis showed that higher intradialytic SBP ARV significantly correlated with MCI (odds ratio [OR], 1.24; 95% CI, 1.01-1.51; P=0.041) when assessed as a continuous variable. The clinical indicators that were significant in the univariate analyses and related to MCI included age (OR, 1.1; 95% CI, 1.06-1.14; P<0.001) and history of diabetes (OR, 6.25; 95% CI, 1.43-27.35; P=0.015).

Significant indicators from the univariate logistic analysis and those considered potentially related to cognitive impairment were included in the multivariable analysis. When tertiles of SBP ARV were considered a categorical variable, both middle (OR, 3.47; 95% CI, 1.33- 9.08; P=0.011) and high tertiles of SBP ARV (OR, 2.71; 95% CI, 1.02-7.25; P=0.047) showed significantly increased odds of MCI versus the low tertile in all models, according to the study findings.

Because high SBP ARV was closely associated with MCI, investigators suggested that it may serve as an indicator in patients receiving MHD. “Further prospective cohort studies are needed to clarify the potential mechanisms between BPV and MCI in MHD patients,” they wrote.