Association of intradialytic blood pressure variability with increased all-cause and cardiovascular mortality in patients treated with long-term hemodialysis.

BACKGROUND: Blood pressure is known to fluctuate widely during hemodialysis; however, little is known about the association between intradialytic blood pressure variability and outcomes. STUDY DESIGN: Retrospective observational cohort. SETTING & PARTICIPANTS: A random sample of 6,393 adult, thrice-weekly, in-center, maintenance hemodialysis patients dialyzing at 1,026 dialysis units within a single large dialysis organization. PREDICTOR: Intradialytic systolic blood pressure (SBP) variability. This was calculated using a mixed linear effects model. Peridialytic SBP phenomena were defined as starting SBP (regression intercept), systematic change in SBP over the course of dialysis (2 regression slopes), and random intradialytic SBP variability (absolute regression residual). OUTCOMES: All-cause and cardiovascular mortality. MEASUREMENTS: SBPs (n = 631,922) measured during hemodialysis treatments (n = 78,961) during the first 30 days in the study. Outcome data were obtained from the dialysis unit electronic medical record and were considered beginning on day 31. RESULTS: High (ie, greater than the median) versus low SBP variability was associated with greater risk of all-cause mortality (adjusted HR, 1.26; 95% CI, 1.08-1.47). The association between high SBP variability and cardiovascular mortality was even more potent (adjusted HR, 1.32; 95% CI, 1.01-1.72). A dose-response trend was observed across quartiles of SBP variability for both all-cause (P = 0.001) and cardiovascular (P = 0.04) mortality. LIMITATIONS: Inclusion of patients from a single large dialysis organization, over-representation of African Americans and patients with diabetes and heart failure, and lack of standardized SBP measurements. CONCLUSIONS: Greater intradialytic SBP variability is associated independently with increased all-cause and cardiovascular mortality. Further prospective studies are needed to confirm findings and identify means of reducing SBP variability to facilitate randomized study.

Factors associated with intradialytic systolic blood pressure variability.

BACKGROUND: Although blood pressure lability during hemodialysis has long been recognized, little is known about factors that promote nonsystematic intradialytic blood pressure variability. STUDY DESIGN: Prospective observational cohort. SETTING & PARTICIPANTS: Random cluster sample of 218 prevalent hemodialysis patients treated at 5 participating DaVita Dialysis units. PREDICTORS: Clinical variables that may plausibly influence intradialytic systolic blood pressure (SBP) variability. OUTCOMES: SBP variability as described by: (1) the deviation of SBP from its anticipated course (primary metric) and (2) the absolute value of the difference between successive SBP measurements (secondary metric). MEASUREMENTS: SBPs measured and recorded (n = 19,170) per clinical protocol during hemodialysis treatments (n = 2,422; median 11 per patient) occurring in the first 30 days of study. Predictors were assessed through standardized interview, examination, and medical record abstraction. RESULTS: Results were similar when SBP variability was considered in terms of the primary and secondary metrics. Older age and longer dialysis vintage were associated with increased SBP variability, whereas other patient characteristics were not. Greater fluid removal during hemodialysis (whether considered as volume or rate either absolute or relative to total-body water) was associated with greater SBP variability independently of its effects on net pre- to posttreatment SBP reduction. Neither number nor dialyzability of antihypertensive medications nor individual classes of agents showed an association with SBP variability. LIMITATIONS: Over-representation of African Americans and patients with congestive heart failure; observational design; use of clinically measured blood pressures; absence of medication adherence confirmation. CONCLUSIONS: Increased intradialytic SBP variability is associated with greater dialytic fluid removal and rate, as well as demographic characteristics, such as older age and dialysis vintage. Further work is needed to confirm these findings and measure associations between SBP variability and clinical outcomes.

A model of systolic blood pressure during the course of dialysis and clinical factors associated with various blood pressure behaviors.

BACKGROUND: Little is known about the behavior of systolic blood pressure (SBP) during hemodialysis. STUDY DESIGN: Prospective observational cohort. SETTING & PARTICIPANTS: 218 prevalent hemodialysis patients treated at 5 participating DaVita Dialysis units. PREDICTORS: Clinical variables that may plausibly influence the behavior of SBP during the course of hemodialysis sessions. OUTCOMES: SBP at the onset of dialysis and its rate of change (slope) over the first 25% and latter 75% of the treatment interval. MEASUREMENTS: SBPs measured and recorded per clinical protocol during the first 30 days of study (median, 11 treatments/patient; SBP measured at 30-minute intervals). RESULTS: Intradialytic SBP behavior is well characterized by a 2-slope linear spline model, which describes SBP at time zero, a rapid decrease during the first 25% of the treatment (early), and a more gradual decrease thereafter (late). Higher ultrafiltration volume and rate each are associated with greater SBP at the start of dialysis and more rapid early and late SBP decreases. Use of a higher number of antihypertensives was associated with greater time zero SBP. Calcium acetate use is associated with high SBP at the start of hemodialysis and a more pronounced decrease during the early and late parts of treatment. LIMITATIONS: Over-representation of blacks and patients with congestive heart failure; observational design; use of clinically measured blood pressures. CONCLUSIONS: Intradialytic SBP can be characterized using 3 parameters: value at the start of dialysis and slopes during the first 25% and latter 75% of treatment. Practices related to fluid management, antihypertensive use, and metabolic bone disease control are associated with blood pressure behavior during dialysis. Further work is needed to confirm findings and measure associations between various aspects of intradialytic blood pressure behavior and clinical outcomes.

A local, regional, and national assessment of pediatric malaria in the United States.

BACKGROUND: Imported malaria remains a public health concern in the United States, but the health impact on children and the financial costs to society have not been well defined. METHODS: Inpatient and outpatient malaria cases diagnosed at Children's National Medical Center (CNMC) in Washington, DC over an 8-year period are retrospectively reviewed. Cases are mapped against Census Bureau population data. These observations are compared with the national burden of pediatric malaria, including both disease severity and cost, by reviewing inpatient malaria cases in the Pediatric Health Information System (PHIS), January 2003 to June 2008. RESULTS: At CNMC, malaria most commonly affects children who traveled to West Africa to visit friends and relatives. Poor adherence to prophylaxis and self-treatment with antimalarial medications were commonly identified. Mapping demonstrates case clustering in communities with large sub-Saharan African populations. The cumulative incidence (CI) of malaria at CNMC of 9.0 per 10,000 admissions is 7.6 times the national average. The CI of malaria at PHIS hospitals is 1.2 per 10,000 admissions with an average cost of $17,519. CONCLUSIONS: Malaria is a preventable disease for which the risk to life and costs of treatment are significant. Patterns of risk can be used by health planners to target prevention strategies at the community level. In regions with a high density of immigrants, particularly from sub-Saharan Africa, physicians must be aware of the risk, understand recommended prophylaxis and treatment regimens, and advocate for their appropriate use in the community.