Original Investigation
Dialysis
Association of Blood Pressure Increases During Hemodialysis With 2-Year Mortality in Incident Hemodialysis Patients: A Secondary Analysis of the Dialysis Morbidity and Mortality Wave 2 Study

https://doi.org/10.1053/j.ajkd.2009.05.012Get rights and content

Background

Intradialytic increases in blood pressure (BP) can complicate the management of hypertension in hemodialysis (HD) patients. However, the long-term consequences are uncertain. Thus, we sought to determine whether BP increases during HD were associated with greater 2-year mortality in incident HD patients.

Study Design

Secondary analysis of a prospective dialysis cohort.

Setting & Participants

Incident HD patients in the Dialysis Morbidity and Mortality Wave 2 Study.

Predictors

Changes in systolic BP (SBP) during HD (ie, postdialysis SBP − predialysis SBP), averaged from 3 HD sessions before enrollment.

Outcome

Time to 2-year all-cause mortality.

Measurements

Cox regression was used to model hazard ratios for mortality associated with changes in SBP during HD while adjusting for demographics, comorbid conditions, interdialytic weight gain, laboratory variables, and antihypertensive agents.

Results

Of 1,748 patients, 12.2% showed greater than 10–mm Hg increases in SBP during HD. In adjusted analyses, every 10–mm Hg increase in SBP during HD was associated independently with a 6% increased hazard of death (hazard ratio, 1.06; 95% confidence interval, 1.01 to 1.11). When also adjusted for diastolic BP and postdialysis SBP, the adjusted hazard of death associated with increasing SBP during HD remained significant (hazard ratio, 1.12; 95% confidence interval, 1.05 to 1.21 per 10–mm Hg increase in SBP during HD). However, in analyses adjusted for predialysis SBP, there was a significant interaction between change in SBP and predialysis SBP. In analyses stratified by predialysis SBP, trends for increased mortality associated with increasing SBP during dialysis were present in patients with predialysis SBP less than 160 mm Hg. However, this relationship was significant only in patients with predialysis SBP less than 120 mm Hg.

Limitations

Secondary analysis with a limited number of baseline BP measurements and limited information about dialysis prescription.

Conclusions

Increasing SBP by more than 10 mm Hg during HD occurs in approximately 10% of incident patients, and although increasing SBP during HD was associated with decreased 2-year survival, these findings were limited to patients with predialysis SBP less than 120 mm Hg.

Section snippets

Study Design

This study is a secondary analysis of a prospective cohort of incident dialysis patients enrolled in the Dialysis Morbidity and Mortality Study (DMMS) Wave 2.

Setting

All incident peritoneal dialysis patients and a 20% random sample of incident HD patients starting dialysis therapy during 1996 and 1997 in the United States were enrolled in the DMMS cohort. Entry into the cohort began 60 days after dialysis therapy initiation, at which time demographics, comorbid conditions, clinical variables,

Participants and Descriptive Data

Of 1,748 incident HD patients, 213 (12.2%) showed increases in SBP during HD greater than 10 mm Hg (Table 1). Figure 1 shows the distribution of changes in SBP during HD across the cohort of patients. In general, patients with intradialytic increases in SBP had lower dry weight, smaller body mass index, and lower interdialytic weight gain compared with patients with SBP that was unchanged or decreased with HD (P < 0.001 for all). Patients with intradialytic increases in SBP also had lower serum

Discussion

Intradialytic increase in BP is a known phenomenon of HD; however, this is the first study to identify its association with adverse 2-year clinical outcomes. Although clinicians often focus on intradialytic hypotension and its complications, intradialytic increases in BP often are largely ignored. Considering that our investigation identified an intradialytic increase in SBP to be associated with an increased hazard of death, particularly in patients with low predialysis SBP, additional

Acknowledgements

The data reported here have been supplied by the USRDS. The interpretation and reporting of these data are the responsibility of the authors and in no way should be seen as an official policy or interpretation of the US government. This work was presented in part at the American Society of Nephrology 41st Annual Meeting, Philadelphia, PA, November 6, 2008.

Support: Dr Inrig was supported by National Institutes of Health (NIH) grant K23 HL092297. Dr Patel was supported by NIH grant K23 DK075929.

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    Originally published online as doi: 10.1053/j.ajkd.2009.05.012 on July 31, 2009.

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