Kamyar Kalantar-Zadeh | University of California, Irvine (original) (raw)

Papers by Kamyar Kalantar-Zadeh

Research paper thumbnail of Abstract 809: Greater Fluid Retention is Associated with Increased Cardiovascular Mortality in Different Groups of CKD Patients on Hemodialysis

Circulation, Oct 28, 2008

Research paper thumbnail of Precision Medicine for Nutritional Management in End-Stage Kidney Disease and Transition to Dialysis

Seminars in nephrology, 2018

Chronic kidney disease (CKD) is a global public health burden. Dialysis is not only costly but ma... more Chronic kidney disease (CKD) is a global public health burden. Dialysis is not only costly but may not be readily available in developing countries. Even in highly developed nations, many patients may prefer to defer or avoid dialysis. Thus, alternative options to dialysis therapy or to complement dialysis are needed urgently and are important objectives in CKD management that could have huge clinical and economic implications globally. The role of nutritional therapy as a strategy to slow CKD progression and uremia was discussed as early as the late 19th and early 20th century, but was only seriously explored in the 1970s. There is a revival of interest recently owing to encouraging data as well as the increase of precision medicine with an emphasis on a personalized approach to CKD management. Although part of the explanation for the inconclusive data may relate to variations in study design and dietary prescription, diversity in genetic make-up, variations in the non-nutritional ...

Research paper thumbnail of 57 a Low, Rather Than a High, Total Plasma Homocysteine is an Indicator of Poor Outcome in Hemodialysis Patients

Journal of Investigative Medicine, 2004

Research paper thumbnail of Intradialytic hypotension, blood pressure changes and mortality risk in incident hemodialysis patients

Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association, Jan 21, 2017

Intradialytic hypotension (IDH) occurs frequently in maintenance hemodialysis (HD) patients and m... more Intradialytic hypotension (IDH) occurs frequently in maintenance hemodialysis (HD) patients and may be associated with higher mortality. We hypothesize that nadir intradialytic systolic blood pressure (niSBP) is inversely related to death risk while iSBP change (Δ) and IDH frequency are incrementally associated with all-cause mortality. In a US-based cohort of 112 013 incident HD patients over a 5-year period (2007-11), using niSBP, ΔiSBP (pre-HD SBP minus niSBP) and IDH frequency (proportion of HD treatments with niSBP <90 mmHg) within the first 91 days of HD, we examined mortality-predictability at 1, 2 and 5 years using Cox models and restricted cubic splines adjusted for case-mix, comorbidities and laboratory covariates. We observed that niSBP of <90 and ≥140 mmHg had a 5-year mortality hazard ratio (HR) (95% confidence interval) of 1.57 (1.47-1.67) and 1.25 (1.18-1.33), respectively, compared with niSBP 110 to <120 mmHg. ΔiSBP of <15 and ≥50 compared with 21-30 mmHg...

Research paper thumbnail of Sex Differences in Hospitalizations with Maintenance Hemodialysis

Journal of the American Society of Nephrology, 2017

Hospitalization is a major source of morbidity among patients with ESRD undergoing maintenance he... more Hospitalization is a major source of morbidity among patients with ESRD undergoing maintenance hemodialysis and is a significant contributor to health care costs. To identify subgroups at the highest risk of hospitalization, we analyzed by sex, age, and race, adjusting for demographic and clinical characteristics, the hospitalization rates, and 30-day readmissions for 333,756 hospitalizations among 111,653 patients undergoing maintenance hemodialysis in facilities operated by a large dialysis organization in the United States (2007–2011). The overall hospitalization rate was 1.85 hospitalizations per person-year and was much higher among women than among men (2.08 versus 1.68 hospitalizations per year for women versus men, P<0.001). Age group–specific hospitalization rates were consistently higher for women than for men of the same race, and the differences were greatest in younger age groups (for example, women aged 18–34 years and ≥75 years had 54% [95% confidence interval, 42%...

Research paper thumbnail of Prediction equation for calculating residual kidney urea clearance using urine collections for different hemodialysis treatment frequencies and interdialytic intervals

Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association, Mar 15, 2017

The purpose of the study was to explore the precision of an equation designed to estimate residua... more The purpose of the study was to explore the precision of an equation designed to estimate residual kidney urea clearance (K RU ) from interdialytic urine collection data and pre-hemodialysis (HD) serum urea nitrogen (SUN) in different hemodialysis treatment schedules. The generalizability of the proposed equation was tested in 32 731 HD treatments where urine was collected prior to a dialysis session, mostly for 24 h but sometimes longer, in patients being dialyzed 1-4 times/week. The residual kidney urea clearance estimating equation predicted a K RU that matched the one computed by formal modeling within 5% in >98% of sessions analyzed. The errors in estimated versus modeled K RU for interdialytic intervals (IDIs) of 2, 3, 4 and 7 days, were 1.6 ± 1.5%, -0.4 ± 1.6%, 0.9 ± 1.6%, and 1.5 ± 1.2%, respectively. Percent errors were similar for schedules of 1-4/week with the exception of urine collection during the 2-day interval of a 2:5-day twice-weekly schedule; here error average...

Research paper thumbnail of Blood Pressure Before Initiation of Maintenance Dialysis and Subsequent Mortality

American Journal of Kidney Diseases, 2017

Research paper thumbnail of Modeling longitudinal data and its impact on survival in observational nephrology studies: tools and considerations

Nephrology Dialysis Transplantation, 2017

Research paper thumbnail of Incremental Hemodialysis: The University of California Irvine Experience

Seminars in Dialysis, 2017

Research paper thumbnail of Changes in urine volume and serum albumin in incident hemodialysis patients

Hemodialysis international. International Symposium on Home Hemodialysis, Oct 25, 2016

Introduction Hypoalbuminemia is a predictor of poor outcomes in dialysis patients. Among hemodial... more Introduction Hypoalbuminemia is a predictor of poor outcomes in dialysis patients. Among hemodialysis patients, there has not been prior study of whether residual kidney function or decline over time impacts serum albumin levels. We hypothesized that a decline in residual kidney function is associated with an increase in serum albumin levels among incident hemodialysis patients. Methods In a large national cohort of 38,504 patients who initiated hemodialysis during 1/2007-12/2011, we examined the association of residual kidney function, ascertained by urine volume and renal urea clearance, with changes in serum albumin over five years across strata of baseline residual kidney function, race, and diabetes using case-mix adjusted linear mixed effects models. Findings Serum albumin levels increased over time. At baseline, patients with greater urine volume had higher serum albumin levels: 3.44 ± 0.48, 3.50 ± 0.46, 3.57 ± 0.44, 3.59 ± 0.45, and 3.65 ± 0.46 g/dL for urine volume groups o...

Research paper thumbnail of Serum uric acid, protein intake and mortality in hemodialysis patients

Nephrology Dialysis Transplantation, 2017

Research paper thumbnail of Association of body weight changes with mortality in incident hemodialysis patients

Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association, Jan 26, 2016

Incident hemodialysis patients may experience rapid weight loss in the first few months of starti... more Incident hemodialysis patients may experience rapid weight loss in the first few months of starting dialysis. However, trends in weight changes over time and their associations with survival have not yet been characterized in this population. In a large contemporary US cohort of 58 106 patients who initiated hemodialysis during 1 January 2007-31 December 2011 and survived the first year of dialysis, we observed trends in weight changes during the first year of treatment and then examined the association of post-dialysis weight changes with all-cause mortality. Patients' post-dialysis weights rapidly decreased and reached a nadir at the 5th month of dialysis with an average decline of 2% from baseline, whereas obese patients (body mass index ≥30 kg/m(2)) did not reach a nadir and lost ∼3.8% of their weight by the 12th month. Compared with the reference group (-2 to 2% changes in weight), the death hazard ratios (HRs) of patients with -6 to -2% and greater than or equal to -6% wei...

Research paper thumbnail of Racial-ethnic disparities in mortality and kidney transplant outcomes among pediatric dialysis patients

Pediatric nephrology (Berlin, Germany), Apr 29, 2016

Previous studies in adult hemodialysis patients have shown that African-American and Hispanic pat... more Previous studies in adult hemodialysis patients have shown that African-American and Hispanic patients have a lower risk of mortality in addition to a lower likelihood of kidney transplantation. However, studies of the association between race and outcomes in pediatric dialysis are sparse and often do not examine outcomes in Hispanic children. The objective was to determine if racial-ethnic disparities in mortality and kidney transplantation outcomes exist in pediatric dialysis patients. This was a retrospective cohort analysis of 2,697 pediatric dialysis patients (aged 0-20 years) from a large national dialysis organization (entry period 2001-2011) of non-Hispanic white, African-American, and Hispanic race-ethnicity. Associations between race-ethnicity with mortality and kidney transplantation outcomes were examined separately using competing risks methods. Logistic regression analyses were used to examine the association between race-ethnicity, with outcomes within 1 year of dialy...

Research paper thumbnail of Serum Magnesium Levels and Hospitalization and Mortality in Incident Peritoneal Dialysis Patients: A Cohort Study

American journal of kidney diseases : the official journal of the National Kidney Foundation, Oct 31, 2016

Prior studies have shown the association of low serum magnesium levels with adverse health outcom... more Prior studies have shown the association of low serum magnesium levels with adverse health outcomes in patients undergoing hemodialysis. There is a paucity of such studies in patients undergoing peritoneal dialysis (PD). Cohort study. 10,692 patients treated with PD from January 1, 2007, through December 31, 2011, in facilities operated by a single large dialysis organization in the United States. Baseline serum magnesium levels, examined as 5 categories (<1.8, 1.8-<2.0, 2.0-<2.2 [reference], 2.2-<2.4, and ≥2.4mg/dL). Time to first hospitalization and time to death using competing-risks regression models. The distribution of baseline serum magnesium levels in the cohort was <1.8mg/dL, 1,928 (18%); 1.8 to <2.0mg/dL, 2,204 (21%); 2.0 to <2.2mg/dL, 2,765 (26%); 2.2 to <2.4mg/dL, 1,765 (16%); and ≥2.4mg/dL, 2,030 (19%). Of 10,692 patients, 6,465 (60%) were hospitalized at least once and 1,392 (13%) died during follow-up (median, 13; IQR, 7-23 months). Baseline se...

Research paper thumbnail of Association between vascular access creation and deceleration of estimated glomerular filtration rate decline in late-stage chronic kidney disease patients transitioning to end-stage renal disease

Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association, Jan 30, 2016

Prior studies have suggested that arteriovenous fistula (AVF) or graft (AVG) creation may be asso... more Prior studies have suggested that arteriovenous fistula (AVF) or graft (AVG) creation may be associated with slowing of estimated glomerular filtration rate (eGFR) decline. It is unclear if this is attributable to the physiological benefits of a mature access on systemic circulation versus confounding factors. We examined a nationwide cohort of 3026 US veterans with advanced chronic kidney disease (CKD) transitioning to dialysis between 2007 and 2011 who had a pre-dialysis AVF/AVG and had at least three outpatient eGFR measurements both before and after AVF/AVG creation. Slopes of eGFR were estimated using mixed-effects models adjusted for fixed and time-dependent confounders, and compared separately for the pre- and post-AVF/AVG period overall and in patients stratified by AVF/AVG maturation. In all, 3514 patients without AVF/AVG who started dialysis with a catheter served as comparators, using an arbitrary 6-month index date before dialysis initiation to assess change in eGFR slop...

Research paper thumbnail of Association of serum vitamin B12 and folate with mortality in incident hemodialysis patients

Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association, Jan 10, 2016

Vitamin B12 (B12) and folate are essential vitamins that play important roles in physiological pr... more Vitamin B12 (B12) and folate are essential vitamins that play important roles in physiological processes. In the general population, many studies have evaluated the association of these vitamins with clinical outcomes, yet this association in hemodialysis (HD) patients remains unclear. We examined the association of serum folate and B12 with mortality in a 5-year cohort of 9517 (folate) and 12 968 (B12) HD patients using Cox models with hierarchical adjustment for sociodemographics, comorbidities, and laboratory variables associated with the malnutrition and inflammation complex syndrome. The associations of baseline B12 and folate (separately) with all-cause mortality were evaluated across five categories of B12 [<400 (reference), 400-<550, 550-<650, 650-<750 and ≥750 pg/mL] and folate [<6.2, 6.2-<8.4, 8.4-<11 (reference), 11-<14.3 and ≥14.3 ng/mL]. The study cohort with B12 measurements had a mean ± standard deviation age of 63 ± 15 years, among whom 43% we...

Research paper thumbnail of Successful Conversion From Parenteral Paricalcitol to Pulse Oral Calcitriol for the Management of Secondary Hyperparathyroidism in Hemodialysis Patients

Journal of Renal Nutrition, 2016

Research paper thumbnail of Serum creatinine as a marker of muscle mass in chronic kidney disease: results of a cross-sectional study and review of literature

Journal of cachexia, sarcopenia and muscle, 2013

Higher muscle mass is associated with better outcomes and longevity in patients with chronic dise... more Higher muscle mass is associated with better outcomes and longevity in patients with chronic disease states. Imaging studies such as dual-energy X-ray absorptiometry (DEXA) are among the gold standard methods for assessing body fat and lean body mass (LBM), approximately half of which is comprised of skeletal muscle mass. Elaborate imaging devices, however, are not commonly available in routine clinical practice and therefore easily accessible and cost-effective, but reliable muscle mass biomarkers are needed. One such marker is serum creatinine, derived from muscle-based creatine, which is inexpensive and ubiquitously available, and it can serve as a biomarker of skeletal muscle mass in human subjects. In 118 hemodialysis patients, we found that the 3-month averaged serum creatinine concentration correlated well with DEXA-measured LBM. The recent literature regarding serum creatinine as a surrogate of muscle mass is summarized, as is the literature concerning the use of other measu...

Research paper thumbnail of Organic and inorganic dietary phosphorus and its management in chronic kidney disease

Iranian journal of kidney diseases, 2010

Dietary phosphorus control is often a main strategy in the management of patients with chronic ki... more Dietary phosphorus control is often a main strategy in the management of patients with chronic kidney disease. Dietary protein is a major source of phosphorus intake. Recent data indicate that imposed dietary phosphorus restriction may compromise the need for adequate protein intake, leading to protein-energy wasting and possibly to increased mortality. The two main sources of dietary phosphorus are organic, including animal and vegetarian proteins, and inorganic, mostly food preservatives. Animal-based foods and plant are abundant in organic phosphorus. Usually 40% to 60% of animal-based phosphorus is absorbed; this varies by degree of gastrointestinal vitamin-D-receptor activation, whereas plant phosphorus, mostly associated with phytates, is less absorbable by human gastrointestinal tract. Up to 100% of inorganic phosphorus in processed foods may be absorbed; ie, phosphorus in processed cheese and some soda (cola) drinks. A recent study suggests that a higher dietary phosphorus-p...

Research paper thumbnail of Association between obesity and health-related quality of life in patients with coronary artery disease

International journal of obesity (2005), 2010

In patients with coronary artery disease (CAD), obesity is paradoxically associated with better s... more In patients with coronary artery disease (CAD), obesity is paradoxically associated with better survival (the 'obesity paradox'). Our objective was to determine whether this counterintuitive relationship extends to health-related quality of life (HRQOL) outcomes. Cross-sectional observational study. All adults undergoing coronary angiography residing in Alberta, Canada between January 2003 and March 2006 in the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) registry. Patients completed self-reported questionnaires 1 year after their index cardiac catheterization, including the Seattle Angina Questionnaire (SAQ) and the EuroQol 5D (EQ-5D Index). Patients were grouped into six body mass index (BMI) categories (underweight, normal, overweight, mild obesity, moderate obesity and severe obesity). An analysis of covariance was used to create risk-adjusted scores. A total of 5362 patients were included in the analysis. Obese patients were you...

Research paper thumbnail of Abstract 809: Greater Fluid Retention is Associated with Increased Cardiovascular Mortality in Different Groups of CKD Patients on Hemodialysis

Circulation, Oct 28, 2008

Research paper thumbnail of Precision Medicine for Nutritional Management in End-Stage Kidney Disease and Transition to Dialysis

Seminars in nephrology, 2018

Chronic kidney disease (CKD) is a global public health burden. Dialysis is not only costly but ma... more Chronic kidney disease (CKD) is a global public health burden. Dialysis is not only costly but may not be readily available in developing countries. Even in highly developed nations, many patients may prefer to defer or avoid dialysis. Thus, alternative options to dialysis therapy or to complement dialysis are needed urgently and are important objectives in CKD management that could have huge clinical and economic implications globally. The role of nutritional therapy as a strategy to slow CKD progression and uremia was discussed as early as the late 19th and early 20th century, but was only seriously explored in the 1970s. There is a revival of interest recently owing to encouraging data as well as the increase of precision medicine with an emphasis on a personalized approach to CKD management. Although part of the explanation for the inconclusive data may relate to variations in study design and dietary prescription, diversity in genetic make-up, variations in the non-nutritional ...

Research paper thumbnail of 57 a Low, Rather Than a High, Total Plasma Homocysteine is an Indicator of Poor Outcome in Hemodialysis Patients

Journal of Investigative Medicine, 2004

Research paper thumbnail of Intradialytic hypotension, blood pressure changes and mortality risk in incident hemodialysis patients

Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association, Jan 21, 2017

Intradialytic hypotension (IDH) occurs frequently in maintenance hemodialysis (HD) patients and m... more Intradialytic hypotension (IDH) occurs frequently in maintenance hemodialysis (HD) patients and may be associated with higher mortality. We hypothesize that nadir intradialytic systolic blood pressure (niSBP) is inversely related to death risk while iSBP change (Δ) and IDH frequency are incrementally associated with all-cause mortality. In a US-based cohort of 112 013 incident HD patients over a 5-year period (2007-11), using niSBP, ΔiSBP (pre-HD SBP minus niSBP) and IDH frequency (proportion of HD treatments with niSBP <90 mmHg) within the first 91 days of HD, we examined mortality-predictability at 1, 2 and 5 years using Cox models and restricted cubic splines adjusted for case-mix, comorbidities and laboratory covariates. We observed that niSBP of <90 and ≥140 mmHg had a 5-year mortality hazard ratio (HR) (95% confidence interval) of 1.57 (1.47-1.67) and 1.25 (1.18-1.33), respectively, compared with niSBP 110 to <120 mmHg. ΔiSBP of <15 and ≥50 compared with 21-30 mmHg...

Research paper thumbnail of Sex Differences in Hospitalizations with Maintenance Hemodialysis

Journal of the American Society of Nephrology, 2017

Hospitalization is a major source of morbidity among patients with ESRD undergoing maintenance he... more Hospitalization is a major source of morbidity among patients with ESRD undergoing maintenance hemodialysis and is a significant contributor to health care costs. To identify subgroups at the highest risk of hospitalization, we analyzed by sex, age, and race, adjusting for demographic and clinical characteristics, the hospitalization rates, and 30-day readmissions for 333,756 hospitalizations among 111,653 patients undergoing maintenance hemodialysis in facilities operated by a large dialysis organization in the United States (2007–2011). The overall hospitalization rate was 1.85 hospitalizations per person-year and was much higher among women than among men (2.08 versus 1.68 hospitalizations per year for women versus men, P<0.001). Age group–specific hospitalization rates were consistently higher for women than for men of the same race, and the differences were greatest in younger age groups (for example, women aged 18–34 years and ≥75 years had 54% [95% confidence interval, 42%...

Research paper thumbnail of Prediction equation for calculating residual kidney urea clearance using urine collections for different hemodialysis treatment frequencies and interdialytic intervals

Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association, Mar 15, 2017

The purpose of the study was to explore the precision of an equation designed to estimate residua... more The purpose of the study was to explore the precision of an equation designed to estimate residual kidney urea clearance (K RU ) from interdialytic urine collection data and pre-hemodialysis (HD) serum urea nitrogen (SUN) in different hemodialysis treatment schedules. The generalizability of the proposed equation was tested in 32 731 HD treatments where urine was collected prior to a dialysis session, mostly for 24 h but sometimes longer, in patients being dialyzed 1-4 times/week. The residual kidney urea clearance estimating equation predicted a K RU that matched the one computed by formal modeling within 5% in >98% of sessions analyzed. The errors in estimated versus modeled K RU for interdialytic intervals (IDIs) of 2, 3, 4 and 7 days, were 1.6 ± 1.5%, -0.4 ± 1.6%, 0.9 ± 1.6%, and 1.5 ± 1.2%, respectively. Percent errors were similar for schedules of 1-4/week with the exception of urine collection during the 2-day interval of a 2:5-day twice-weekly schedule; here error average...

Research paper thumbnail of Blood Pressure Before Initiation of Maintenance Dialysis and Subsequent Mortality

American Journal of Kidney Diseases, 2017

Research paper thumbnail of Modeling longitudinal data and its impact on survival in observational nephrology studies: tools and considerations

Nephrology Dialysis Transplantation, 2017

Research paper thumbnail of Incremental Hemodialysis: The University of California Irvine Experience

Seminars in Dialysis, 2017

Research paper thumbnail of Changes in urine volume and serum albumin in incident hemodialysis patients

Hemodialysis international. International Symposium on Home Hemodialysis, Oct 25, 2016

Introduction Hypoalbuminemia is a predictor of poor outcomes in dialysis patients. Among hemodial... more Introduction Hypoalbuminemia is a predictor of poor outcomes in dialysis patients. Among hemodialysis patients, there has not been prior study of whether residual kidney function or decline over time impacts serum albumin levels. We hypothesized that a decline in residual kidney function is associated with an increase in serum albumin levels among incident hemodialysis patients. Methods In a large national cohort of 38,504 patients who initiated hemodialysis during 1/2007-12/2011, we examined the association of residual kidney function, ascertained by urine volume and renal urea clearance, with changes in serum albumin over five years across strata of baseline residual kidney function, race, and diabetes using case-mix adjusted linear mixed effects models. Findings Serum albumin levels increased over time. At baseline, patients with greater urine volume had higher serum albumin levels: 3.44 ± 0.48, 3.50 ± 0.46, 3.57 ± 0.44, 3.59 ± 0.45, and 3.65 ± 0.46 g/dL for urine volume groups o...

Research paper thumbnail of Serum uric acid, protein intake and mortality in hemodialysis patients

Nephrology Dialysis Transplantation, 2017

Research paper thumbnail of Association of body weight changes with mortality in incident hemodialysis patients

Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association, Jan 26, 2016

Incident hemodialysis patients may experience rapid weight loss in the first few months of starti... more Incident hemodialysis patients may experience rapid weight loss in the first few months of starting dialysis. However, trends in weight changes over time and their associations with survival have not yet been characterized in this population. In a large contemporary US cohort of 58 106 patients who initiated hemodialysis during 1 January 2007-31 December 2011 and survived the first year of dialysis, we observed trends in weight changes during the first year of treatment and then examined the association of post-dialysis weight changes with all-cause mortality. Patients' post-dialysis weights rapidly decreased and reached a nadir at the 5th month of dialysis with an average decline of 2% from baseline, whereas obese patients (body mass index ≥30 kg/m(2)) did not reach a nadir and lost ∼3.8% of their weight by the 12th month. Compared with the reference group (-2 to 2% changes in weight), the death hazard ratios (HRs) of patients with -6 to -2% and greater than or equal to -6% wei...

Research paper thumbnail of Racial-ethnic disparities in mortality and kidney transplant outcomes among pediatric dialysis patients

Pediatric nephrology (Berlin, Germany), Apr 29, 2016

Previous studies in adult hemodialysis patients have shown that African-American and Hispanic pat... more Previous studies in adult hemodialysis patients have shown that African-American and Hispanic patients have a lower risk of mortality in addition to a lower likelihood of kidney transplantation. However, studies of the association between race and outcomes in pediatric dialysis are sparse and often do not examine outcomes in Hispanic children. The objective was to determine if racial-ethnic disparities in mortality and kidney transplantation outcomes exist in pediatric dialysis patients. This was a retrospective cohort analysis of 2,697 pediatric dialysis patients (aged 0-20 years) from a large national dialysis organization (entry period 2001-2011) of non-Hispanic white, African-American, and Hispanic race-ethnicity. Associations between race-ethnicity with mortality and kidney transplantation outcomes were examined separately using competing risks methods. Logistic regression analyses were used to examine the association between race-ethnicity, with outcomes within 1 year of dialy...

Research paper thumbnail of Serum Magnesium Levels and Hospitalization and Mortality in Incident Peritoneal Dialysis Patients: A Cohort Study

American journal of kidney diseases : the official journal of the National Kidney Foundation, Oct 31, 2016

Prior studies have shown the association of low serum magnesium levels with adverse health outcom... more Prior studies have shown the association of low serum magnesium levels with adverse health outcomes in patients undergoing hemodialysis. There is a paucity of such studies in patients undergoing peritoneal dialysis (PD). Cohort study. 10,692 patients treated with PD from January 1, 2007, through December 31, 2011, in facilities operated by a single large dialysis organization in the United States. Baseline serum magnesium levels, examined as 5 categories (<1.8, 1.8-<2.0, 2.0-<2.2 [reference], 2.2-<2.4, and ≥2.4mg/dL). Time to first hospitalization and time to death using competing-risks regression models. The distribution of baseline serum magnesium levels in the cohort was <1.8mg/dL, 1,928 (18%); 1.8 to <2.0mg/dL, 2,204 (21%); 2.0 to <2.2mg/dL, 2,765 (26%); 2.2 to <2.4mg/dL, 1,765 (16%); and ≥2.4mg/dL, 2,030 (19%). Of 10,692 patients, 6,465 (60%) were hospitalized at least once and 1,392 (13%) died during follow-up (median, 13; IQR, 7-23 months). Baseline se...

Research paper thumbnail of Association between vascular access creation and deceleration of estimated glomerular filtration rate decline in late-stage chronic kidney disease patients transitioning to end-stage renal disease

Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association, Jan 30, 2016

Prior studies have suggested that arteriovenous fistula (AVF) or graft (AVG) creation may be asso... more Prior studies have suggested that arteriovenous fistula (AVF) or graft (AVG) creation may be associated with slowing of estimated glomerular filtration rate (eGFR) decline. It is unclear if this is attributable to the physiological benefits of a mature access on systemic circulation versus confounding factors. We examined a nationwide cohort of 3026 US veterans with advanced chronic kidney disease (CKD) transitioning to dialysis between 2007 and 2011 who had a pre-dialysis AVF/AVG and had at least three outpatient eGFR measurements both before and after AVF/AVG creation. Slopes of eGFR were estimated using mixed-effects models adjusted for fixed and time-dependent confounders, and compared separately for the pre- and post-AVF/AVG period overall and in patients stratified by AVF/AVG maturation. In all, 3514 patients without AVF/AVG who started dialysis with a catheter served as comparators, using an arbitrary 6-month index date before dialysis initiation to assess change in eGFR slop...

Research paper thumbnail of Association of serum vitamin B12 and folate with mortality in incident hemodialysis patients

Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association, Jan 10, 2016

Vitamin B12 (B12) and folate are essential vitamins that play important roles in physiological pr... more Vitamin B12 (B12) and folate are essential vitamins that play important roles in physiological processes. In the general population, many studies have evaluated the association of these vitamins with clinical outcomes, yet this association in hemodialysis (HD) patients remains unclear. We examined the association of serum folate and B12 with mortality in a 5-year cohort of 9517 (folate) and 12 968 (B12) HD patients using Cox models with hierarchical adjustment for sociodemographics, comorbidities, and laboratory variables associated with the malnutrition and inflammation complex syndrome. The associations of baseline B12 and folate (separately) with all-cause mortality were evaluated across five categories of B12 [<400 (reference), 400-<550, 550-<650, 650-<750 and ≥750 pg/mL] and folate [<6.2, 6.2-<8.4, 8.4-<11 (reference), 11-<14.3 and ≥14.3 ng/mL]. The study cohort with B12 measurements had a mean ± standard deviation age of 63 ± 15 years, among whom 43% we...

Research paper thumbnail of Successful Conversion From Parenteral Paricalcitol to Pulse Oral Calcitriol for the Management of Secondary Hyperparathyroidism in Hemodialysis Patients

Journal of Renal Nutrition, 2016

Research paper thumbnail of Serum creatinine as a marker of muscle mass in chronic kidney disease: results of a cross-sectional study and review of literature

Journal of cachexia, sarcopenia and muscle, 2013

Higher muscle mass is associated with better outcomes and longevity in patients with chronic dise... more Higher muscle mass is associated with better outcomes and longevity in patients with chronic disease states. Imaging studies such as dual-energy X-ray absorptiometry (DEXA) are among the gold standard methods for assessing body fat and lean body mass (LBM), approximately half of which is comprised of skeletal muscle mass. Elaborate imaging devices, however, are not commonly available in routine clinical practice and therefore easily accessible and cost-effective, but reliable muscle mass biomarkers are needed. One such marker is serum creatinine, derived from muscle-based creatine, which is inexpensive and ubiquitously available, and it can serve as a biomarker of skeletal muscle mass in human subjects. In 118 hemodialysis patients, we found that the 3-month averaged serum creatinine concentration correlated well with DEXA-measured LBM. The recent literature regarding serum creatinine as a surrogate of muscle mass is summarized, as is the literature concerning the use of other measu...

Research paper thumbnail of Organic and inorganic dietary phosphorus and its management in chronic kidney disease

Iranian journal of kidney diseases, 2010

Dietary phosphorus control is often a main strategy in the management of patients with chronic ki... more Dietary phosphorus control is often a main strategy in the management of patients with chronic kidney disease. Dietary protein is a major source of phosphorus intake. Recent data indicate that imposed dietary phosphorus restriction may compromise the need for adequate protein intake, leading to protein-energy wasting and possibly to increased mortality. The two main sources of dietary phosphorus are organic, including animal and vegetarian proteins, and inorganic, mostly food preservatives. Animal-based foods and plant are abundant in organic phosphorus. Usually 40% to 60% of animal-based phosphorus is absorbed; this varies by degree of gastrointestinal vitamin-D-receptor activation, whereas plant phosphorus, mostly associated with phytates, is less absorbable by human gastrointestinal tract. Up to 100% of inorganic phosphorus in processed foods may be absorbed; ie, phosphorus in processed cheese and some soda (cola) drinks. A recent study suggests that a higher dietary phosphorus-p...

Research paper thumbnail of Association between obesity and health-related quality of life in patients with coronary artery disease

International journal of obesity (2005), 2010

In patients with coronary artery disease (CAD), obesity is paradoxically associated with better s... more In patients with coronary artery disease (CAD), obesity is paradoxically associated with better survival (the 'obesity paradox'). Our objective was to determine whether this counterintuitive relationship extends to health-related quality of life (HRQOL) outcomes. Cross-sectional observational study. All adults undergoing coronary angiography residing in Alberta, Canada between January 2003 and March 2006 in the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) registry. Patients completed self-reported questionnaires 1 year after their index cardiac catheterization, including the Seattle Angina Questionnaire (SAQ) and the EuroQol 5D (EQ-5D Index). Patients were grouped into six body mass index (BMI) categories (underweight, normal, overweight, mild obesity, moderate obesity and severe obesity). An analysis of covariance was used to create risk-adjusted scores. A total of 5362 patients were included in the analysis. Obese patients were you...