Peridialysis BP levels and risk of all-cause mortality: a dose-response meta-analysis

Hypertension in Dialysis Patients: Diagnostic Approaches and Evaluation of Epidemiology

Whereas hypertension is an established cardiovascular risk factor in the general population, the contribution of increased blood pressure (BP) to the huge burden of cardiovascular morbidity and mortality in patients receiving dialysis continues to be debated. In a large part, this controversy is attributable to particular difficulties in the accurate diagnosis of hypertension. The reverse epidemiology of hypertension in dialysis patients is based on evidence from large cohort studies showing that routine predialysis or postdialysis BP measurements exhibit a U-shaped or J-shaped association with cardiovascular or all-cause mortality. However, substantial evidence supports the notion that home or ambulatory BP measurements are superior to dialysis-unit BP recordings in diagnosing hypertension, in detecting evidence of target-organ damage and in prognosticating the all-cause death risk. In the first part of this article, we explore the accuracy of different methods of BP measurement in diagnosing hypertension among patients on dialysis. In the second part, we describe how the epidemiology of hypertension is modified when the assessment of BP is based on dialysis-unit versus home or ambulatory recordings.

Paradoxical Association Between Intradialytic Blood Pressure Change and Long-Term Mortality with Different Levels of Interdialytic Weight Gain

Background

A greater interdialytic weight gain (IDWG) implies a greater ultrafiltration rate, which might lead to hemodynamic instability and intradialytic blood pressure (BP) change in hemodialysis patients. However, current studies have not explicated the impact of IDWG on the association between intradialytic BP changes and prognosis, especially in patients without cardiac dysfunction and diabetes. In this study, we aimed to explore the relationship between absolute intradialytic BP changes and mortality with different IDWG levels.

Methods

A total of 204 hemodialysis patients (without cardiac dysfunction and diabetes) were included in this prospective observation study, with a mean follow-up of 55.32±20.99 months. Initially, we collected IDWG, IDWG% (percentages according to dry weight), and pre-/post-BPs of 36 consecutive dialysis sessions during three months enrollment. And the average value of them was defined as baseline value. Patients were divided into 3 cohorts according to IDWG% tertiles (<3.3%, 3.3%-4.6%, ≥4.6%). Comparisons between different tertiles were analyzed.

Results

Compared to the low IDWG% group (tertile 1, T1), patients of high IDWG% group (tertile 3, T3) were younger, had higher ultrafiltration rate, less residual kidney function, lower BMI and dry weight, longer dialysis vintage and higher N terminal pro B type natriuretic peptide levels (P<0.05). Correlations were found between IDWG% and intradialytic BP changes. Kaplan-Meier analysis and multivariate Cox regression model adjusted for demographic data, dialysis information and predialysis BPs indicated that greater absolute intradialytic BP changes were associated with worse prognosis in T1 group (P<0.05). While in T3 group, less absolute intradialytic BP changes were associated with higher mortality (P<0.05).

Conclusion

There is a paradoxical association between absolute intradialytic BP changes and long-term mortality with different IDWG levels. Both BP stability and volume balance are crucial to patients' prognosis.

Intradialytic systolic blood pressure variation can predict long-term mortality in patients on maintenance hemodialysis

PURPOSE

It is unclear which time-points of intradialytic blood pressure (BP) best predict prognosis. Thus, it is important to assess the association between different time-points of intradialytic BP and prognosis in clinical practice.

METHODS

We recruited patients who underwent hemodialysis from January 2014 to June 2014. Data about dialysis were collected, including intradialytic BP. Cox regression analysis was performed to examine the association between different time-points of intradialytic BP and clinical events, with a follow-up through December 31, 2019. The primary endpoint was all-cause mortality.

RESULTS

A total of 216 patients were recruited and 62 (30.7%) patients died (6.1 per 100-person year) during the follow-up. Intradialytic SBP varied greatly in fatalities. Univariate and multivariate Cox regression models indicated that the adjusted hazard ratio for death was 1.80 and 5.06 when intradialytic systolic blood pressure (SBP) variation was analyzed in increments of 20 mmHg. Furthermore, we divided intradialytic SBP variation into three categories: < 15 mmHg, 15 ~ 30 mmHg,  ≥ 30 mmHg. Kaplan-Meier analysis indicated that both all-cause mortality and cardiovascular mortality increased significantly for patients with intradialytic SBP variation over 30 mmHg (P = 0.006 and 0.021). Univariate and multivariate Cox regression models indicated that the adjusted hazard ratio for death was 3.78 and 12.62 as intradialytic SBP variation ≥ 30 mmHg vs. intradialytic SBP variation < 15 mmHg.

CONCLUSION

Intradialytic SBP variation, rather than BP of specific intradialytic time-points, has the potential to predict long-term mortality in hemodialysis patients. BP stability is crucial for patients' prognosis.