Charles J. McAllister

Bio: Charles J. McAllister is an academic researcher from DaVita. The author has contributed to research in topics: Hazard ratio & Hemodialysis. The author has an hindex of 24, co-authored 28 publications receiving 5236 citations.

Associations Between Changes in Hemoglobin and Administered Erythropoiesis-Stimulating Agent and Survival in Hemodialysis Patients

Abstract: Although treating anemia of chronic kidney disease by erythropoiesis-stimulating agents (ESA) may improve survival, most studies have examined associations between baseline hemoglobin values and survival and ignored variations in clinical and laboratory measures over time. It is not clear whether longitudinal changes in hemoglobin or administered ESA have meaningful associations with survival after adjustment for time-varying confounders. With the use of time-dependent Cox regression models, longitudinal associations were examined between survival and quarterly (13-wk averaged) hemoglobin values and administered ESA dose in a 2-yr (July 2001 to June 2003) cohort of 58,058 maintenance hemodialysis patients from a large dialysis organization (DaVita) in the United States. After time-dependent and multivariate adjustment for case mix, quarterly varying administered intravenous iron and ESA doses, iron markers, and nutritional status, hemoglobin levels between 12 and 13 g/dl were associated with the greatest survival. Among prevalent patients, the lower range of the recommended Kidney Disease Quality Outcomes Initiative hemoglobin target (11 to 11.5 g/dl) was associated with a higher death risk compared with the 11.5- to 12-g/dl range. A decrease or increase in hemoglobin over time was associated with higher or lower death risk, respectively, independent of baseline hemoglobin. Administration of any dose of ESA was associated with better survival, whereas among those who received ESA, requiring higher doses were surrogates of higher death risk. In this observational study, greater survival was associated with a baseline hemoglobin between 12 and 13 g/dl, treatment with ESA, and rising hemoglobin. Falling hemoglobin and requiring higher ESA doses were associated with decreased survival. Randomized clinical trials are required to examine these associations.

Serum and Dialysate Potassium Concentrations and Survival in Hemodialysis Patients

Abstract: Background and objectives: Controlling serum potassium is an important goal in maintenance hemodialysis patients. We examined the achievement of potassium balance through hemodialysis treatments and the associated fluctuations in serum potassium. Design, setting, participants, & measurements: A 3-yr (July 2001 to June 2004) cohort of 81,013 maintenance hemodialysis patients from all DaVita dialysis clinics across the United States were studied. Nine quarterly-averaged serum potassium groups ( Results: Serum potassium correlated with nutritional markers. Serum potassium between 4.6 and 5.3 mEq/L was associated with the greatest survival, whereas potassium Conclusions: A predialysis serum potassium of 4.6 to 5.3 mEq/L is associated with the greatest survival in maintenance hemodialysis patients. Hyperkalemic patients who undergo maintenance hemodialysis against lower dialysate bath may have better survival. Limitations of observational studies including confounding by indication should be considered when interpreting these results.

Revisiting mortality predictability of serum albumin in the dialysis population: time dependency, longitudinal changes and population-attributable fraction

Abstract: Background. Hypoalbuminaemia is a marker of malnutrition–inflammation complex syndrome (MICS) and a strong predictor of cardiovascular (CV) death in maintenance haemodialysis (MHD) patients. However, serum albumin may change over time. Hence, its time-varying associations with outcome may be different. Methods. Associations between 3-month averaged serum albumin levels, measured in a single laboratory using bromocresol green, and CV mortality were studied longitudinally in a 2-year cohort of 58 058 MHD patients. Mortality predictability of fixed baseline and trimonthly-varying serum albumin concentrations were compared. Results. Hazard ratios (HRs) of CV death strictly increased across decrements of baseline serum albumin, whereas the HR for time-varying serum albumin decrements below 3.8 g/dl did not differ. A drop in serum albumin in the first 6 months was associated with increasing all-cause and CV death risks in the subsequent 18 months, while a rise in serum albumin was a predictor of better survival independent of baseline serum albumin. The multivariate adjusted population-attributable fraction of death due to baseline serum albumin 3.8 g/dl might reduce the number of MHD deaths in the USA by � 10 000 annually. Nutritional interventions examining benefits of increasing serum albumin in MHD patients are urgently needed.

Normalization of Hemoglobin Level in Patients with Chronic Kidney Disease and Anemia

Abstract: BACKGROUND Whether correction of anemia in patients with stage 3 or 4 chronic kidney disease improves cardiovascular outcomes is not established. METHODS We randomly assigned 603 patients with an estimated glomerular filtration rate (GFR) of 15.0 to 35.0 ml per minute per 1.73 m 2 of body-surface area and mild-to-moderate anemia (hemoglobin level, 11.0 to 12.5 g per deciliter) to a target hemoglobin value in the normal range (13.0 to 15.0 g per deciliter, group 1) or the subnormal range (10.5 to 11.5 g per deciliter, group 2). Subcutaneous erythropoietin (epoetin beta) was initiated at randomization (group 1) or only after the hemoglobin level fell below 10.5 g per deciliter (group 2). The primary end point was a composite of eight cardiovascular events; secondary end points included left ventricular mass index, quality-of-life scores, and the progression of chronic kidney disease. RESULTS During the 3-year study, complete correction of anemia did not affect the likelihood of a first cardiovascular event (58 events in group 1 vs. 47 events in group 2; hazard ratio, 0.78; 95% confidence interval, 0.53 to 1.14; P = 0.20). Left ventricular mass index remained stable in both groups. The mean estimated GFR was 24.9 ml per minute in group 1 and 24.2 ml per minute in group 2 at baseline and decreased by 3.6 and 3.1 ml per minute per year, respectively (P = 0.40). Dialysis was required in more patients in group 1 than in group 2 (127 vs. 111, P = 0.03). General health and physical function improved significantly (P = 0.003 and P<0.001, respectively, in group 1, as compared with group 2). There was no significant difference in the combined incidence of adverse events between the two groups, but hypertensive episodes and headaches were more prevalent in group 1. CONCLUSIONS In patients with chronic kidney disease, early complete correction of anemia does not reduce the risk of cardiovascular events. (ClinicalTrials.gov number, NCT00321919.)

Fibroblast growth factor 23 and mortality among patients undergoing hemodialysis.

Abstract: BACKGROUND Fibroblast growth factor 23 (FGF-23) is a hormone that increases the rate of urinary excretion of phosphate and inhibits renal production of 1,25-dihydroxyvitamin D, thus helping to mitigate hyperphosphatemia in patients with kidney disease. Hyperphosphatemia and low 1,25-dihydroxyvitamin D levels are associated with mortality among patients with chronic kidney disease, but the effect of the level of FGF-23 on mortality is unknown. METHODS We examined mortality according to serum phosphate levels in a prospective cohort of 10,044 patients who were beginning hemodialysis treatment and then analyzed FGF-23 levels and mortality in a nested case-control sample of 200 subjects who died and 200 who survived during the first year of hemodialysis treatment. We hypothesized that increased FGF-23 levels at the initiation of hemodialysis would be associated with increased mortality. RESULTS Serum phosphate levels in the highest quartile (>5.5 mg per deciliter [1.8 mmol per liter]) were associated with a 20% increase in the multivariable adjusted risk of death, as compared with normal levels (3.5 to 4.5 mg per deciliter [1.1 to 1.4 mmol per liter]) (hazard ratio, 1.2; 95% confidence interval [CI], 1.1 to 1.4). Median C-terminal FGF-23 (cFGF-23) levels were significantly higher in case subjects than in controls (2260 vs. 1406 reference units per milliliter, P<0.001). Multivariable adjusted analyses showed that increasing FGF-23 levels were associated with a monotonically increasing risk of death when examined either on a continuous scale (odds ratio per unit increase in log-transformed cFGF-23 values, 1.8; 95% CI, 1.4 to 2.4) or in quartiles, with quartile 1 as the reference category (odds ratio for quartile 2, 1.6 [95% CI, 0.8 to 3.3]; for quartile 3, 4.5 [95% CI, 2.2 to 9.4]; and for quartile 4, 5.7 [95% CI, 2.6 to 12.6]). CONCLUSIONS Increased FGF-23 levels appear to be independently associated with mortality among patients who are beginning hemodialysis treatment. Future studies might investigate whether FGF-23 is a potential biomarker that can be used to guide strategies for the management of phosphorus balance in patients with chronic kidney disease.