Background Calcium-phosphate levels, linked to vascular dysfunction in chronic kidney disease, may represent novel risk factors for coronary heart disease, stroke, and death in community-dwelling ...adults. Methods We tested this hypothesis over 12.6 years of follow-up in the prospective, community-based Atherosclerosis Risk in Communities Study (n = 15,732). Results At baseline, mean (SD) values were 9.8 (0.4) mg/dL for serum calcium, 3.4 (0.5) mg/dL for serum phosphate, 33.6 (5.3) mg2 /dL2 for calcium-phosphate product, 54.2 (5.7) years for age, and 93.1 (21.5) mL/min per 1.73 m2 for glomerular filtration rate (GFR). Shared associations of calcium, phosphate, and calcium-phosphate product included older age, female sex, African American race, cigarette-years, current cigarette smoking, low body mass index, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, low serum albumin, low GFR, low caloric intake, and phosphorus intake. With adjustment for age, demographic characteristics, comorbid conditions, albumin, and GFR, calcium-associated hazards ratios for coronary heart disease, stroke, and death were, respectively, 1.01 (95% confidence interval 0.96-1.06), 1.16 (1.07-1.26, P = .0005), and 1.03 (0.98-1.08); phosphate-associated hazards ratios were 1.03 (0.98-1.08), 1.11 (1.02-1.21, P = .0219), and 1.14 (1.09-1.20, P < .0001); calcium-phosphate product-associated hazards ratios were 1.03 (0.98-1.08), 1.15 (1.05-1.26, P = .0017), and 1.15 (1.09-1.20, P < .0001). Conclusions Although calcium, phosphate, and calcium-phosphate product levels exhibit complex associations with traditional cardiovascular risk factors and outcomes, they may be potentially modifiable risk factors for stroke and death in community-dwelling adults.
Confronted with the decision to initiate dialysis, patients and caregivers often seek information about how expected survival chances evolve, both initially and afterward, providing the patient ...survives beyond arbitrary periods of time. Large registry data, used to examine these issues, may be subject to early ascertainment bias, such as those accruing from nonregistration of with end-stage kidney disease who die shortly after dialysis initiation and inclusion of patients with acute kidney injury with slower than typical recovery rates. Despite these caveats, available studies have suggested that mortality hazards are much higher in the first 3 months of renal replacement therapy. Prominent modifiable associations of early mortality include late referral to nephrology services, initial dialysis with vascular catheters, and, most problematically, higher glomerular filtration rates at initiation of renal replacement therapy. Despite their imperfections, currently available information is relatively user-unfriendly and could be better leveraged to help patients and treatment teams make better decisions.
Background The prevalence of moderate to severe cognitive impairment in hemodialysis patients is more than double the prevalence in the general population. This study describes cognitive impairment ...occurrence in a peritoneal dialysis cohort compared with a cohort without chronic kidney disease (CKD). Study Design Cross-sectional study. Setting & Participants 51 English-speaking peritoneal dialysis patients from 2 urban dialysis units compared with 338 hemodialysis patients from 16 urban dialysis units and 101 voluntary controls without CKD from urban general medicine clinics. Predictor 45-minute battery of 9 validated neuropsychological tests (cognitive domains memory, executive function, and language). Outcomes Mild, moderate, or severe cognitive impairment, classified according to a previously designed algorithm. Results Of the peritoneal dialysis cohort, 33.3% had no or mild, 35.3% had moderate, and 31.4% had severe cognitive impairment; corresponding values were 60.4%, 26.7%, and 12.9% of the non-CKD cohort and 26.6%, 36.4%, and 37.0% of the hemodialysis cohort. A logistic regression model including age, sex, race, education, hemoglobin level, diabetes, and stroke showed that only nonwhite race ( P = 0.002) and low education ( P = 0.002) were associated with moderate to severe cognitive impairment in the peritoneal dialysis cohort. Compared with hemodialysis patients, more peritoneal dialysis patients had moderate to severe memory impairment (58% vs 51%), but fewer had impaired executive function (one-third vs one-half). Peritoneal dialysis was associated with a more than 2.5-fold increased risk of moderate to severe global cognitive impairment compared with no CKD (OR, 2.58; 95% CI, 1.02-6.53), as was hemodialysis (OR, 3.16; 95% CI, 1.91-5.24), in an adjusted logistic regression model. Limitations Small sample size, participation rate somewhat low. Conclusions Similar to hemodialysis patients, two-thirds of peritoneal dialysis patients had moderate to severe cognitive impairment, enough to interfere with safely self-administering dialysis and adhering to complex medication regimens. These patients could benefit from cognitive assessment before and periodically after dialysis therapy initiation.
Background Autosomal dominant polycystic kidney disease (ADPKD) is amenable to early detection and specialty care. Thus, while important to patients with the condition, end-stage renal disease (ESRD) ...from ADPKD also may be an indicator of the overall state of nephrology care. Study Design Retrospective cohort study of temporal trends in ESRD from ADPKD and pre–renal replacement therapy (RRT) nephrologist care, 2001-2010 (n = 23,772). Setting & Participants US patients who initiated maintenance RRT from 2001 through 2010 (n = 1,069,343) from US Renal Data System data. Predictor ESRD from ADPKD versus from other causes for baseline characteristics and clinical outcomes; interval 2001-2005 versus 2006-2010 for comparisons of cohort of patients with ESRD from ADPKD. Outcomes Death, wait-listing for kidney transplant, kidney transplantation. Measurements US census data were used as population denominators. Poisson distribution was used to compute incidence rates (IRs). Incidence ratios were standardized to rates in 2001-2002 for age, sex, and race/ethnicity. Patients with and without ADPKD were matched to compare clinical outcomes. Poisson regression was used to calculate IRs and adjusted HRs for clinical events after inception of RRT. Results General population incidence ratios in 2009-2010 were unchanged from 2001-2002 (incidence ratio, 1.02). Of patients with ADPKD, 48.1% received more than 12 months of nephrology care before RRT; preemptive transplantation was the initial RRT in 14.3% and fistula was the initial hemodialysis access in 35.8%. During 4.9 years of follow-up, patients with ADPKD were more likely to be listed for transplantation (IR, 11.7 95% CI, 11.5-12.0 vs 8.4 95% CI, 8.2-8.7 per 100 person-years) and to undergo transplantation (IR, 9.8 95% CI, 9.5-10.0 vs 4.8 95% CI, 4.7-5.0 per 100 person-years) and less likely to die (IR, 5.6 95% CI, 5.4-5.7 vs 15.5 95% CI, 15.3-15.8 per 100 person-years) than matched controls without ADPKD. Limitations Retrospective nonexperimental registry-based study of associations; cause-and-effect relationships cannot be determined. Conclusions Although outcomes on dialysis therapy are better for patients with ADPKD than for those without ADPKD, access to predialysis nephrology care and nondeclining ESRD rates may be a cause for concern.
Background Estimates of chronic kidney disease (CKD) in the United States using the continuous National Health and Nutrition Examination Survey (NHANES) data set 1999-2004 indicate that 13.1% of the ...population (26.3 million people based on the 2000 census) has CKD stages 1 to 4. Study Design We performed sensitivity analyses to highlight assumptions underlying these estimates and illustrate their robustness to varying assumptions. Setting & Participants NHANES 1999-2004 was a nationally representative cross-sectional continuous survey of the civilian noninstitutionalized US population. Our sample included participants 20 years and older. Reference Test Estimated glomerular filtration rate (GFR) less than 60 mL/min/1.73 m2 defined from the 4-variable Modification of Diet in Renal Disease (MDRD) Study equation; albuminuria defined as persistence of urinary albumin-creatinine ratio greater than 30 mg/g. Index Tests We compared prevalence estimates using the MDRD Study equation with 2 other GFR estimating equations (equation 5 by Rule et al from the Mayo Clinic Donors study; Cockcroft-Gault equation adjusted for body surface area and corrected for the bias in the MDRD Study sample), and sex-specific cutoff values to define albuminuria. Results We found CKD stages 1 to 4 prevalence estimates ranging from 11.7% to 24.9%, a more than 2-fold difference resulting in population estimates of 25.8 million to 54.0 million people using 2006 population estimates. Considering only stages 3 and 4, which are not affected by the choice of cutoff values to define albuminuria, prevalence estimates ranged from 6.3% to 18.6%, resulting in population estimates of 13.7 million to 40.3 million people, a nearly 3-fold difference. Limitations NHANES 1999-2004 is a cross-sectional survey and allows for GFR and albumin-creatinine ratio estimates at 1 point in time. NHANES does not account for seniors in long-term care facilities. Conclusions Although CKD prevalence is high regardless of varying modeling assumptions, different assumptions yield large differences in prevalence estimates.
Background Although cognitive function in hemodialysis patients is believed to be best 24 hours after the dialysis session, the extent of variation during the dialysis cycle is unknown. Study Design ...Cohort study with repeated measures. Setting & Participants Hemodialysis centers; patients aged 55 years or older. Predictor Time of assessment related to the dialysis session. Time 1 (T1) occurred approximately 1 hour before the dialysis session; T2, 1 hour into the session; T3, 1 hour after; and T4, the next day. Outcomes Measures of cognitive function using a 45-minute cognitive battery. An average composite score was calculated to measure global cognitive function, equal to the average of subjects’ standardized scores on all tests given at each test time. Times were classified as best and worst according to composite scores. Measurements Testing was conducted on average over 2 dialysis sessions to avoid test fatigue. The cognitive battery included tests of verbal fluency, immediate and delayed verbal and visual memory, and executive function, administered at 4 times. Results In the 28 subjects who completed testing at 3 or 4 testing times, mean age was 66.7 ± 9.5 years and mean dialysis vintage was 44.7 ± 33.3 months. Using a general linear model for correlated data, the composite score was significantly lower (poorer) during dialysis (T2) than shortly before the session (T1) or on the next day (T4; P < 0.001 for both). Limitations Relatively small sample size, testing delays, results may not be generalizable. Conclusion Global cognitive function varies significantly during the dialysis cycle, being worst during dialysis and best shortly before the session or on the day after. Clinician visits may be most effective at these times.
To address the highly complex interrelated nature of chronic kidney disease (CKD) and diabetes, hypertension, and cardiovascular disease, we examined CKD prevalence by the predictive effect of ...demographic factors, comorbid conditions, and CKD risk factors by using National Health and Nutrition Examination Survey (NHANES) 1999-2004 data. NHANES is a nationally representative cross-sectional series of surveys with a complex stratified multistage sampling design. NHANES 1999-2004 participants (n = 15,332; age ≥ 20 years) were interviewed in their homes and asked to participate in standardized medical examinations in mobile centers and provide samples for laboratory tests. Weighted logistic regression modeling was used to assess the importance of individual CKD risk factors. Multiple logistic regressions were performed on patient cohorts, with increasing levels of CKD severity defined by means of estimated glomerular filtration rate. A branching diagram was constructed to address the distribution of CKD grouped by diabetes, hypertension, and cardiovascular disease status. CKD prevalence increases with age (39.2% for age ≥ 60 years). For ages 20 to 59 years, CKD prevalence was greater for participants with diabetes (33.8%) than for those without diabetes (8.2%) and for participants with both diabetes and hypertension (43%) than for diabetic participants without hypertension (25.5%) or nondiabetic participants with hypertension (15.2%). The prevalence was 6.8% for nondiabetic participants without hypertension. Effects of cardiovascular disease are less dramatic when hypertension and diabetes are considered. A CKD screening approach targeting individuals 60 years and older or those with diabetes or hypertension likely would be useful from a public health standpoint.
Background Studies addressing patterns and trends in red blood cell transfusion use in US hemodialysis patients surprisingly have received little attention in the last decade. Study Design ...Retrospective cohort study. Setting & Participants Point prevalent (as of January 1 of each calendar year 1992 to 2005) dialysis patients with Medicare Part A and Part B as primary insurance (n = 77,347 in 1992, n = 164,933 in 2005). The 6 months preceding January 1 of each year were used to assemble a comorbidity profile based on administrative claims data. Predictors Hemoglobin levels, patient characteristics, comorbid conditions. Outcomes Blood transfusion events obtained from Part A and Part B files using code files for both whole and packed red blood cell transfusions and hemoglobin levels. Measurements Comorbid conditions were defined by the presence of 1 or more inpatient/outpatient institutional claims (inpatient hospitalization, skilled nursing facility, or home health agency), 2 or more outpatient or physician/supplier claims, or 1 or more outpatient and 1 or more physician/supplier claims for atherosclerotic heart disease, congestive heart failure, cerebrovascular accidents/transient ischemic attacks, peripheral vascular disease, other cardiovascular diseases, chronic obstructive pulmonary disease, gastrointestinal disorders, liver disease, arrhythmia, and diabetes mellitus. Results Raw transfusion rates decreased in both outpatient and inpatient settings from 535.33/1,000 patient-years for 1992 prevalent dialysis patients to 263.65/1,000 patient-years in 2005 ( P for trend < 0.001, 1992 versus 1999 and 1999 versus 2005). Adjusted rates decreased similarly. This phenomenon could not be explained by changes in case mix. Limitations Cause, effect, and confounding cannot be separated in this observational study. The accuracy of blood transfusion billing data is unknown. Temporal trends may be related to factors other than erythropoiesis-stimulating agent use. Conclusion Transfusion events in hemodialysis patients decreased more than 2-fold from 1992 to 2005; most of the decrease occurred in the first 5 years after erythropoietin was introduced.
The US Renal Data System Coordinating Center identifies patients with chronic kidney disease (CKD) in administrative data sets and determines the overall size of the population with a diagnosis of ...CKD, with such major comorbid conditions as diabetes and congestive heart failure, and associated expenditures. A 2-year observation period is used to define individuals with at least 1 International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis code from inpatient claims or at least 2 from outpatient claims or physician and supplier service claims for kidney disease and comorbid conditions. This method is applied to the 5% general Medicare data and extrapolated to the general Medicare population. In the Medicare and dually enrolled Medicare/Medicaid populations, 8% to 10% have CKD or end-stage renal disease, and these groups account for 27% to 35% of expenditures. Hospitalization rates for all patients with cardiovascular disease, congestive heart failure, infection, and pneumonia are greatest for dialysis patients and patients with CKD compared with patients without CKD. Regarding detection in groups at high risk of CKD, approximately 1 in 5 patients with diabetes, only 1 in 50 patients with hypertension, and 1 in 4 patients with diabetes and hypertension had at least 1 microalbuminuria test in a year. CKD is a major public health issue with large financial implications. Continued surveillance and detection programs are needed to address the burden of disease, level of comorbidity, and access to care. Long-term trend analyses are needed to determine whether morbidity and mortality rates change based on greater detection and treatment efforts.
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