Patients receiving hemodialysis have high rates of cardiovascular morbidity and mortality that may be related to the hemodynamic effects of rapid ultrafiltration. Here we tested whether higher dialytic ultrafiltration rates are associated with greater all-cause and cardiovascular mortality, and hospitalization for cardiovascular disease. We used data from the Hemodialysis Study, an almost-7-year randomized clinical trial of 1846 patients receiving thrice-weekly chronic dialysis. The ultrafiltration rates were divided into three categories: up to 10 ml/h/kg, 10–13 ml/h/kg, and over 13 ml/h/kg. Compared to ultrafiltration rates in the lowest group, rates in the highest were significantly associated with increased all-cause and cardiovascular-related mortality with adjusted hazard ratios of 1.59 and 1.71, respectively. Overall, ultrafiltration rates between 10–13 ml/h/kg were not associated with all-cause or cardiovascular mortality; however, they were significantly associated among participants with congestive heart failure. Cubic spline interpolation suggested that the risk of all-cause and cardiovascular mortality began to increase at ultrafiltration rates over 10 ml/h/kg regardless of the status of congestive heart failure. Hence, higher ultrafiltration rates in hemodialysis patients are associated with a greater risk of all-cause and cardiovascular death.

Intradialytic hypotension is a serious and frequent complication of hemodialysis; however, there is no evidence-based consensus definition of intradialytic hypotension. As a result, coherent evaluation of the effects of intradialytic hypotension is difficult. We analyzed data from 1409 patients in the HEMO Study and 10,392 patients from a single large dialysis organization to investigate the associations of commonly used intradialytic hypotension definitions and mortality. Intradialytic hypotension definitions were selected a priori on the basis of literature review. For each definition, patients were characterized as having intradialytic hypotension if they met the corresponding definition in at least 30% of baseline exposure period treatments or characterized as control otherwise. Overall and within subgroups of patients with predialysis systolic BP,120 or 120-159 mmHg, an absolute nadir systolic BP,90 mmHg was most potently associated with mortality. Within the subgroup of patients with predialysis BP$160 mmHg, nadir BP,100 mmHg was most potently associated with mortality. Intradialytic hypotension definitions that considered symptoms, interventions, and decreases in BP during dialysis were not associated with outcome, and when added to nadir BP, symptom and intervention criteria did not accentuate associations with mortality. Our results suggest that nadir-based definitions best capture the association between intradialytic hypotension and mortality.

SummaryBackground and objectives At least four definitions of AKI have recently been proposed. This study sought to characterize the epidemiology of AKI according to the most recent consensus definition proposed by the Kidney Disease Improving Global Outcomes (KDIGO) Work Group, and to compare it with three other definitions.Design, setting, participants, & measurements This was a retrospective cohort study of 31,970 hospitalizations at an academic medical center in 2010. AKI was defined and staged according to KDIGO criteria, the Acute Dialysis Quality Initiative's RIFLE criteria, the Acute Kidney Injury Network (AKIN) criteria, and a definition based on a model of creatinine kinetics (CK). Outcomes of interest were incidence, in-hospital mortality, length of stay, costs, readmission rates, and posthospitalization disposition.Results AKI incidence was highest according to the KDIGO definition (18.3%) followed by the AKIN (16.6%), RIFLE (16.1%), and CK (7.0%) definitions. AKI incidence appeared markedly higher in those with low baseline serum creatinine according to the KDIGO, AKIN, and RIFLE definitions, in which AKI may be defined by a 50% increase over baseline. AKI according to all definitions was associated with a significantly higher risk of death and higher resource utilization. The adjusted odds ratios for in-hospital mortality in those with AKI were highest with the CK definition (5.2; 95% confidence interval [95% CI], 4.1 to 6.6), followed by the RIFLE (2.9; 95% CI, 2.2 to 3.6), KDIGO (2.8; 95% CI, 2.2 to 3.6), and AKIN (2.6; 95% CI, 2.0 to 3.3) definitions. Concordance in diagnosis and staging was high among the KDIGO, AKIN, and RIFLE definitions. ConclusionsThe incidence of AKI in hospitalized individuals varies depending on the definition used. AKI according to all definitions is associated with higher in-hospital mortality and resource utilization. AKI may be inappropriately diagnosed in those with low baseline serum creatinine using definitions that incorporate percentage increases over baseline.