Biomedical subjects

J Michael Lazarus

Publications and source records attributed to J Michael Lazarus.

22 records · Page 2Linked to original sources

PubMed2003

Interactions between dialysis-related volume exposures, nutritional surrogates and mortality among ESRD patients.

BACKGROUND: Interdialytic weight gain is used as a surrogate for volume expansion in haemodialysis patients and as an indicator of non-compliance. Increased weight gain is associated with both a greater mortality risk and better nutrition indices. This analysis characterizes the association between dialysis-related volume expansion and mortality in the context of its interaction with nutritional surrogates. METHODS: All patients receiving haemodialysis through Fresenius Medical Care-North America during 1998 were included. The percentage reduction in weight or intradialytic weight loss (IDWL%) was defined as the difference between the average of pre- and post-dialysis weights from the last 3 months of 1997 expressed as a percentage of post-dialysis weight. Associations between IDWL% and clinical and demographic variables were estimated using linear regression. The association between mortality risk and IDWL% was estimated using Cox proportional hazards regression. RESULTS: Younger age, male gender, the presence of diabetes mellitus, decreasing cholesterol, post-dialysis weight and pre-dialysis blood pressure (systolic and pulse pressure) were associated with increased IDWL%. Increasing IDWL% was associated with increasing phosphorus, creatinine, albumin, potassium and urea reduction ratio. Increasing IDWL% was significantly associated with mortality at 1 year [hazard ratio (HR) = 1.07, P = 0.003]. Among patients with diabetes mellitus, increasing IDWL% was associated with a mortality HR of 1.03 (P = 0.02). Among patients without diabetes mellitus, increasing IDWL% was not associated with an increased mortality risk. Increasing IDWL% is associated with a greater mortality risk among patients with creatinine <7.26, which failed to remain significant for patients whose creatinine was >or=7.26 mg/dl. Increasing IDWL% is associated with a greater mortality risk among patients with greater post-dialysis weight, greater body mass index and lower serum sodium measurements. CONCLUSIONS: This study confirms and extends the findings of the deleterious association between increasing IDWL% and mortality among patients with diabetes mellitus and among subgroups based on serum creatinine and body weight. The putative deleterious effect of dialysis-related volume expansion on mortality must be interpreted in the context of the patient's diabetic and nutritional status.

Adolescent↗

PubMed2002

Association between pulse pressure and mortality in patients undergoing maintenance hemodialysis.

CONTEXT: Although increased blood pressure is associated with adverse outcomes in the general population, elevated blood pressure is associated with decreased mortality in patients with end-stage renal disease undergoing maintenance hemodialysis. Recent investigations in the general population have demonstrated the predictive utility of pulse pressure (systolic minus diastolic blood pressure), a measure reflecting the pulsatile nature of the cardiac cycle. OBJECTIVES: To estimate the relationship between pulse pressure and mortality in patients undergoing maintenance hemodialysis and to test our hypothesis that an increasing pulse pressure would be associated with increased risk of death up to 1 year despite the inverse relationship between conventional blood pressure measures and mortality in patients with end-stage renal disease. DESIGN, SETTING, AND PATIENTS: Retrospective cohort investigation of patients with end-stage renal disease undergoing maintenance hemodialysis at 782 hemodialysis facilities throughout the United States. Of 44 069 eligible patients as of January 1, 1998, 37 069 with complete demographic data were included in the analyses of clinical and laboratory data collected from October 1 through December 31, 1997. Patients were followed up through December 31, 1998. MAIN OUTCOME MEASURES: The primary study outcome was death at 1 year. A secondary outcome was the magnitude of the pulse pressure. RESULTS: The final patient cohort was similar to national averages with respect to age, sex, race, and diabetic status. Mean (SD) pulse pressures before dialysis were 75.0 (15.0) mm Hg and 66.9 (13.9) mm Hg after dialysis. By the end of the 1-year follow-up, 5731 patients (18.4%) died. After adjusting for level of systolic blood pressure, multivariable Cox proportional hazards modeling showed a direct and consistent relationship between increasing pulse pressure and increasing death risk. Each incremental elevation of 10 mm Hg in postdialysis pulse pressure was associated with a 12% increase in the hazard for death (hazard ratio, 1.12; 95% confidence interval, 1.06-1.18). Postdialysis systolic blood pressure was inversely related to mortality with a 13% decreased hazard for death for each incremental elevation of 10 mm Hg (hazard ratio, 0.87; 95% confidence interval, 0.84-0.90). In a multivariable linear regression model, important variables directly associated with elevated pulse pressure included age, diabetes, white race, female sex, and number of years receiving dialysis (all P<.001). CONCLUSIONS: Pulse pressure is associated with risk of death in a large, nationally representative sample of patients undergoing maintenance hemodialysis. The recognition of pulse pressure as an important correlate of mortality in patients receiving dialysis highlights the need to investigate the relationship between potential therapeutic implications of conduit vessel function and clinical outcomes in patients with end-stage renal disease.

Age Factors↗

PubMed2002

Body size, dialysis dose and death risk relationships among hemodialysis patients.

BACKGROUND: The normalized treatment ratio, Kt/V derived from urea kinetic models (UKM), is a commonly used measure of dialysis dose. This measure assumes that smaller patients with low volume of urea distribution (V) require proportionately less total treatment (Kt) than larger patients. The conclusion has been questioned because the UKM use assumptions that could make them invalid for accurately predicting a clinical outcome like survival. It is possible that a relationship exists between Kt and body size whereby a different Kt is required for different sizes. This study therefore explored the relationships among body size, Kt, and death risk focusing on possible interactions between Kt and size. METHODS: The sample included 43,334 patients treated on January 1, 1999. Survival time was modeled using Kt or body size groups to evaluate the shape of the risk profiles. Kt and the size measures were then evaluated together as continuous functions both in main effects (that is, Kt and size) and interaction models to see if the association of Kt with risk might be different for different sizes. The size measures were body weight, weight adjusted statistically for height, body surface area (BSA), weight divided by height (wt/ht) and the body mass index (BMI). RESULTS: The log of risk decreased in rough linear fashion for Kt, weight, weight for height, and BSA. The log-risk relationships were "reverse J-shaped" for wt/ht and BMI. The main effects models suggested improved survival with increasing Kt and all of the size measures. Adding an interaction term increased the benefit associated with increasing Kt and for weight, weight for height and BSA at low values of Kt and size. A significant, positive interaction term mitigated those effects at higher values. Thus, the death risk penalties associated with reducing Kt among small patients were as great as or greater than they were among large patients. A similar pattern was observed for V. Adding the interaction to the BMI model destroyed the main effects, so that there was no significant association between risk and either Kt or BMI. A cross-categorical model of BMI and Kt, however, revealed improving survival with increasing Kt among both low and high BMI patients throughout the range of Kt. CONCLUSIONS: Evidence supporting the intuition that smaller patients require proportionately lower dialysis dose than larger patients was not found. To the contrary, smaller patients suffer as much risk as or more risk than larger patients from reducing Kt. Deciding dialysis treatment using a Kt/V based intuition may lead to avoidable under-dialysis particularly among small patients.

Adult↗

PubMedDate not supplied

Dialyzer best practice: single use or reuse?

Outcome studies have shown either no additional risk or a small additional risk for hospitalization and mortality associated with reprocessing dialyzers. Although the risks from reprocessing dialyzers have yet to be fully elucidated, reuse can be done safely if it is performed in full compliance with the standards of Association for the Advancement of Medical Instrumentation (AAMI). Like most industrial processes, however, complete control of the reuse process in a clinical environment and full compliance with regulations at all times is difficult. Potential errors and breakdowns in the reuse process are continuing concerns. The quality controls for reprocessing of dialyzers are not equal to the rigor of the manufacturing process under the purview of the U.S. Food and Drug Administration (FDA). Therefore, if one were to determine "best practice," single use is preferable to reuse of dialyzers based on medical criteria and risk assessment. The long-term and cumulative effects of exposure to reuse reagents are unknown and there is no compelling medical indication for reprocessing of dialyzers. The major impediment when deciding to convert from reuse to single use of dialyzers is economic. The experience in Fresenius Medical Care-North America (FMCNA) facilities demonstrates that converting from a practice of reuse to single use is achievable. However, the overall economic impact of conversion to single use is provider specific. The dominance of reuse has been negated of late by a major shift in practice toward single use. Physicians and patients should be well informed in making decisions regarding the practice of single use versus reuse of dialyzers.

Disinfection↗