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3.  APOL1 Risk Variants, Race, and Progression of Chronic Kidney Disease 
The New England journal of medicine  2013;369(23):2183-2196.
BACKGROUND
Among patients in the United States with chronic kidney disease, black patients are at increased risk for end-stage renal disease, as compared with white patients.
METHODS
In two studies, we examined the effects of variants in the gene encoding apolipoprotein L1 (APOL1) on the progression of chronic kidney disease. In the African American Study of Kidney Disease and Hypertension (AASK), we evaluated 693 black patients with chronic kidney disease attributed to hypertension. In the Chronic Renal Insufficiency Cohort (CRIC) study, we evaluated 2955 white patients and black patients with chronic kidney disease (46% of whom had diabetes) according to whether they had 2 copies of high-risk APOL1 variants (APOL1 high-risk group) or 0 or 1 copy (APOL1 low-risk group). In the AASK study, the primary outcome was a composite of end-stage renal disease or a doubling of the serum creatinine level. In the CRIC study, the primary outcomes were the slope in the estimated glomerular filtration rate (eGFR) and the composite of end-stage renal disease or a reduction of 50% in the eGFR from baseline.
RESULTS
In the AASK study, the primary outcome occurred in 58.1% of the patients in the APOL1 high-risk group and in 36.6% of those in the APOL1 low-risk group (hazard ratio in the high-risk group, 1.88; P<0.001). There was no interaction between APOL1 status and trial interventions or the presence of baseline proteinuria. In the CRIC study, black patients in the APOL1 high-risk group had a more rapid decline in the eGFR and a higher risk of the composite renal outcome than did white patients, among those with diabetes and those without diabetes (P<0.001 for all comparisons).
CONCLUSIONS
Renal risk variants in APOL1 were associated with the higher rates of end-stage renal disease and progression of chronic kidney disease that were observed in black patients as compared with white patients, regardless of diabetes status. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and others.)
doi:10.1056/NEJMoa1310345
PMCID: PMC3969022  PMID: 24206458
4.  Depressive symptoms and chronic kidney disease: results from the National Health and Nutrition Examination Survey (NHANES) 2005–2006 
International urology and nephrology  2010;42(4):1063-1068.
Background and objective
Depression is common in individuals with end-stage renal disease. However, its relationship with earlier stages of chronic kidney disease (CKD) is less well known. In this study, we examined the association between depressive symptoms and CKD.
Methods
Cross-sectional analysis of the prevalence and correlates of depressive symptoms were measured by the Patient Health Questionnaire (PHQ-9) among adult participants with CKD in the National Health and Nutrition Examination Survey 2005–2006. CKD was defined according to estimated glomerular filtration rate by Modification of Diet in Renal Disease Study equation of <60 ml/min/1.73 m2 or the presence of microalbuminuria (≥30 mg/g creatinine), using the Kidney Disease Outcomes Quality Initiative classification. A PHQ-9 score ≥ 10 was considered to be indicative of depressive symptoms.
Results
Among 3653 subjects in our study sample, 683 (15.2%) met laboratory criteria for CKD. The prevalence of depressive symptoms was 7% (95% confidence interval [CI] 3.2–10.8%) in subjects with CKD and 6% (95% CI 4.6–7.4%) in subjects without CKD (P = 0.6). In regression analysis, the presence of CKD was not significantly associated with depressive symptoms (adjusted odds ratio = 0.96 [95% CI 0.51, 1.78], P = 0.9).
Conclusions
We found no difference in the prevalence of depressive symptoms among individuals with or without CKD.
doi:10.1007/s11255-010-9833-5
PMCID: PMC3951180  PMID: 20949318
Chronic kidney disease; Depression; National Health and Nutrition Examination Survey; Prevalence
5.  Limited health literacy is associated with low glomerular filtration in the Chronic Renal Insufficiency Cohort (CRIC) study 
Clinical nephrology  2014;81(1):30-37.
Background
Low health literacy in the general population is associated with increased risk of death and hospitalization. The evaluation of health literacy in individuals with predialysis chronic kidney disease (CKD) is limited.
Methods
We conducted a cross-sectional study to evaluate the associations of limited health literacy with kidney function and cardiovascular disease (CVD) risk factors in 2,340 non-Hispanic (NH) Whites and Blacks aged 21 – 74 years with mild-to-moderate CKD. Limited health literacy was defined as a Short Test of Functional Health Literacy in Adults (STOFHLA) score ≤ 22. Outcomes evaluated included estimated glomerular filtration rate (eGFR), 24-hour urine protein excretion, and CVD risk factors.
Results
The prevalence of limited health literacy was 28% in NH-Blacks and 5% in NH-Whites. Compared with participants with adequate health literacy, those with limited health literacy were more likely to have lower eGFR (34 vs. 42 mL/min/1.73 m2); higher urine protein/24-hours (0.31 vs. 0.15 g); and higher self-reported CVD (61 vs. 37%); and were less likely to have BP < 130/80 mmHg (51 vs. 58%); p ≤ 0.01 for each comparison. After adjustment, limited health literacy was associated with self-reported CVD (OR 1.51, 95% CI 1.13 – 2.03) and lower eGFR (β − 2.47, p = 0.03).
Conclusion
In this CKD cohort, limited health literacy was highly prevalent, especially among NH-Blacks, and it was associated with lower eGFR and a less favorable CVD risk factor profile. Further studies are needed to better understand these associations and inform the development of health literacy interventions among individuals with CKD.
doi:10.5414/CN108062
PMCID: PMC3951206  PMID: 24219913
chronic kidney disease; health literacy
6.  Sleep Disturbances as Nontraditional Risk Factors for Development and Progression of CKD: Review of the Evidence 
Despite the high prevalence and enormous public health implications of chronic kidney disease (CKD), the factors responsible for its development and progression remain incompletely understood. To date, only a few studies have attempted to objectively characterize sleep in CKD patients prior to kidney failure, but emerging evidence suggests a high prevalence of sleep disorders, particularly obstructive sleep apnea. Laboratory and epidemiologic studies have shown that insufficient sleep and poor sleep quality promote the development and exacerbate the severity of three important risk factors for CKD, namely hypertension, type 2 diabetes, and obesity. In addition, sleep disturbances might have a direct effect on CKD through chronobiological alterations in the renin-angiotensin-aldosterone system and sympathetic nervous system activation. The negative impact of sleep disorders on vascular compliance and endothelial function may also have also have a deleterious effect on CKD. Sleep disturbances may therefore represent a novel risk factor for the development and progression of CKD. Optimizing sleep duration and quality and treating sleep disorders may reduce the severity and delay the progression of CKD.
doi:10.1053/j.ajkd.2012.04.027
PMCID: PMC3461247  PMID: 22727724
Sleep disorders; obstructive sleep apnea; chronic kidney disease
7.  A TRIAL OF TWO STRATEGIES TO REDUCE NOCTURNAL BLOOD PRESSURE IN AFRICAN AMERICANS WITH CHRONIC KIDNEY DISEASE 
Hypertension  2012;61(1):82-88.
The objective of our study was to determine the effects of two antihypertensive drug dose schedules (‘PM dose’ and ‘Add on dose’) on nocturnal blood pressure (BP) in comparison to usual therapy (‘AM dose’) in African Americans with hypertensive chronic kidney disease (CKD) and controlled office BP. In a three period, cross-over trial, former participants of the African American Study of Kidney Disease were assigned to receive the following three regimens, each lasting 6 weeks, presented in random order: AM dose (once daily antihypertensive medications taken in the morning), PM dose (once daily antihypertensives taken at bedtime) and ‘Add on dose’ (once daily antihypertensives taken in the morning and an additional antihypertensive medication before bedtime [diltiazem 60–120 mg, hydralazine 25 mg, or additional ramipril 5 mg]). Ambulatory BP monitoring was performed at the end of each period. The primary outcome was nocturnal systolic BP. Mean age of the study population (n=147) was 65.4 years, 64% were male, mean estimated GFR was 44.9 ml/min/1.73 m2. At the end of each period, mean (SE) nocturnal systolic BP was 125.6 (1.2) mm Hg in the AM dose, 123.9 (1.2) mm Hg in the PM dose, and 123.5(1.2) mm Hg in the Add-on dose. None of the pairwise differences in nocturnal, 24-hour and daytime systolic BP were statistically significant. Among African Americans with hypertensive CKD, neither PM (bedtime) dosing of once daily antihypertensive nor the addition of drugs taken at bedtime significantly reduced nocturnal BP compared to morning dosing of anti-hypertensive medications.
doi:10.1161/HYPERTENSIONAHA.112.200477
PMCID: PMC3523681  PMID: 23172931
Nocturnal blood pressure; chronic kidney disease; hypertension
8.  Risk Factors for Coronary Artery Calcium Among Patients with Chronic Kidney Disease (From the Chronic Renal Insufficiency Cohort Study) 
The American journal of cardiology  2012;110(12):1735-1741.
Cardiovascular disease is the leading cause of death in patients with chronic kidney disease (CKD). We examined the cross-sectional association between novel risk factors and coronary artery calcium (CAC) measured by electron-beam computed tomography or multidetector computed tomography among 2,018 patients with CKD. Based on total Agatston scores, participants were classified as no (0), moderate (>0–100) or high (>100) CAC. After adjustment for age, sex, race, study sites, cigarette smoking, prior cardiovascular disease, hypertension, and diabetes, use of lipid-lowering drugs, body-mass index, waist circumference, and cystatin C, several novel risk factors were significantly associated with high CAC. For example, odds ratios (95% confidence interval) of high CAC associated with one standard deviation higher levels of risk factors were 1.20 (1.04, 1.38) for serum calcium, 1.21 (1.04, 1.41) for serum phosphate, 0.83 (0.71, 0.97) for log (total parathyroid hormone), 1.21 (1.03, 1.43) for log (HOMA-insulin resistance), and 1.23 (1.04, 1.45) for hemoglobin A1c. Additionally, the multivariable-adjusted odds ratio for one standard deviation higher level of cystatin C was 1.31 (1.14, 1.50). Serum high-sensitive C-reactive protein, interleukin-6, tumor necrosis factor-α, and homocysteine were not statistically significantly associated with high CAC. In conclusion, these data indicate that abnormal calcium and phosphate metabolism, insulin resistance, and declined kidney function were associated with the prevalence of high CAC independent of traditional risk factors in patients with CKD. Further studies are warranted to examine the causal effect of these risk factors on CAC in CKD patients.
doi:10.1016/j.amjcard.2012.07.044
PMCID: PMC3511639  PMID: 22980963
calcium; chronic kidney disease; coronary artery calcium; cystatin C; insulin-resistance; phosphate; total parathyroid hormone
9.  Illicit Drug Use, Hypertension, and Chronic Kidney Disease in the U.S. Adult Population 
Illicit drug use has been associated with chronic kidney disease (CKD) in select populations but it is unknown if the same association exists in the general population. Using data from the National Health and Nutrition Examination Survey 2005-2008, we conducted a cross-sectional analysis of 5,861 adults who were questioned about illicit drug use including cocaine, methamphetamines, or heroin during their lifetime. The primary outcome was CKD as defined by an estimated glomerular filtration rate (eGFR) ≤60mL/min/1.73m2 using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation or by microalbuminuria. We also examined the association between illicit drug use and blood pressure (BP) ≥120/80, ≥130/85, and ≥140/90. Logistic regression was used to examine the association between illicit drug use and CKD and BP. Mean eGFR was similar between illicit drug users and non-users (100.7 vs. 101.4mL/min/1.73m2, p=0.4) as was albuminuria (5.7 vs. 6.0mg/g creatinine, p=0.5). Accordingly, illicit drug use was not significantly associated with CKD in logistic regression models (odds ratio [OR] 0.98, confidence interval [CI] 0.75-1.27) after adjusting for other important factors. However, illicit drug users had higher systolic (120 vs. 118mmHg, p=0.04) and diastolic BP (73 vs. 71mmHg, p=0.0003) compared to non-users. Also, cocaine use was independently associated with BP≥130/85 (OR 1.24, CI 1.00-1.54), especially when used more during a lifetime (6-49 times, OR 1.42, CI 1.06-1.91). In a representative sample of the U.S. population, illicit drug use was not associated with CKD but cocaine users were more likely to have elevated blood pressures.
doi:10.1016/j.trsl.2012.05.008
PMCID: PMC3461092  PMID: 22735028
10.  Fibroblast growth factor 23 is not associated with and does not induce arterial calcification 
Kidney international  2013;83(6):1159-1168.
Elevated fibroblast growth factor 23 (FGF23) is associated with cardiovascular disease in patients with chronic kidney disease. As a potential mediating mechanism, FGF23 induces left ventricular hypertrophy; however, its role in arterial calcification is less clear. In order to study this we quantified coronary artery and thoracic aorta calcium by computed tomography in 1501 patients from the Chronic Renal Insufficiency Cohort (CRIC) study within a median of 376 days (interquartile range 331 to 420 days) of baseline. Baseline plasma FGF23 was not associated with prevalence or severity of coronary artery calcium after multivariable adjustment. In contrast, higher serum phosphate levels were associated with prevalence and severity of coronary artery calcium, even after adjustment for FGF23. Neither FGF23 nor serum phosphate were consistently associated with thoracic aorta calcium. We could not detect mRNA expression of FGF23 or its co-receptor, klotho, in human or mouse vascular smooth muscle cells, or normal or calcified mouse aorta. Whereas elevated phosphate concentrations induced calcification in vitro, FGF23 had no effect on phosphate uptake or phosphate-induced calcification regardless of phosphate concentration or even in the presence of soluble klotho. Thus, in contrast to serum phosphate, FGF23 is not associated with arterial calcification and does not promote calcification experimentally. Hence, phosphate and FGF23 promote cardiovascular disease through distinct mechanisms.
doi:10.1038/ki.2013.3
PMCID: PMC3672330  PMID: 23389416
phosphate; fibroblast growth factor 23; vascular calcification; vascular smooth muscle; chronic kidney disease
11.  Recruitment of Hispanics into an Observational Study of Chronic Kidney Disease:The Hispanic Chronic Renal Insufficiency Cohort Study Experience 
Contemporary clinical trials  2012;33(6):1238-1244.
Despite the large burden of chronic kidney disease (CKD) in Hispanics, this population has been underrepresented in research studies. We describe the recruitment strategies employed by the Hispanic Chronic Renal Insufficiency Cohort Study, which led to the successful enrollment of a large population of Hispanic adults with CKD into a prospective observational cohort study. Recruitment efforts by bilingual staff focused on community clinics with Hispanic providers in high-density Hispanic neighborhoods in Chicago, academic medical centers, and private nephrology practices. Methods of publicizing the study included church meetings, local Hispanic print media, Spanish television and radio stations, and local health fairs. From October 2005 to July 2008, we recruited 327 Hispanics aged 21–74 years with mild-to-moderate CKD as determined by age-specific estimated glomerular filtration rate (eGFR). Of 716 individuals completing a screening visit, 49% did not meet eGFR inclusion criteria and 46% completed a baseline visit. The mean age at enrollment was 57.1 and 67.1% of participants were male. Approximately 75% of enrolled individuals were Mexican American, 15% Puerto Rican, and 10% had other Latin American ancestry. Eighty two percent of participants were Spanish-speakers. Community-based and academic primary care clinics yielded the highest percentage of participants screened (45.9% and 22.4%) and enrolled (38.2% and 24.5%). However, academic and community-based specialty clinics achieved the highest enrollment yield from individuals screened (61.9% to 71.4%). A strategy focused on primary care and nephrology clinics and the use of bilingual recruiters allowed us to overcome barriers to the recruitment of Hispanics with CKD.
doi:10.1016/j.cct.2012.07.012
PMCID: PMC3594841  PMID: 22841929
12.  Predictors of high sensitivity cardiac troponin T in chronic kidney disease patients: a cross-sectional study in the chronic renal insufficiency cohort (CRIC) 
BMC Nephrology  2013;14:229.
Background
Cardiac troponin T is independently associated with cardiovascular events and mortality in patients with chronic kidney disease (CKD). Serum levels of high sensitivity cardiac troponin T (hs-TnT) reflect subclinical myocardial injury in ambulatory patients. We sought to determine the distribution and predictors of hs-TnT in CKD patients without overt cardiovascular disease (CVD).
Methods
We studied 2464 participants within the multi-ethnic Chronic Renal Insufficiency Cohort (CRIC) who did not have self-reported CVD. We considered renal and non-renal factors as potential determinants of hs-TnT, including demographics, comorbidities, left ventricular (LV) mass, serologic factors, estimated glomerular filtration rate (eGFR) and albumin to creatinine ratio.
Results
Hs-TnT was detectable in 81% of subjects, and the median (IQR) hs-TnT was 9.4 pg/ml (4.3-18.3). Analysis was performed using Tobit regression, adjusting for renal and non-renal factors. After adjustment, lower eGFR was associated with higher expected hs-TnT; participants with eGFR < 30 ml/min/1.73 m2 had 3-fold higher expected hs-TnT compared to subjects with eGFR > 60. Older age, male gender, black race, LV mass, diabetes and higher blood pressure all had strong, independent associations with higher expected hs-TnT.
Conclusions
Knowledge of the determinants of hs-TnT in this cohort may guide further research on the pathology of heart disease in patients with CKD and help to stratify sub-groups of CKD patients at higher cardiovascular risk.
doi:10.1186/1471-2369-14-229
PMCID: PMC4016297  PMID: 24148285
Troponin T; Chronic kidney disease; Cardiovascular disease
13.  Estimating GFR Among Participants in the Chronic Renal Insufficiency Cohort (CRIC) Study 
Background
Glomerular filtration rate (GFR) is considered the best measure of kidney function, but repeated assessment is not feasible in most research studies.
Study Design
Cross-sectional study of 1,433 participants from the Chronic Renal Insufficiency Cohort (CRIC) Study (i.e., the GFR subcohort) to derive an internal GFR estimating equation using a split sample approach.
Setting & Participants
Adults from 7 US metropolitan areas with mild to moderate chronic kidney disease; 48% had diabetes and 37% were black.
Index Test
CRIC GFR estimating equation
Reference Test or Outcome
Urinary 125I-iothalamate clearance testing (measured GFR)
Other Measurements
Laboratory measures including serum creatinine and cystatin C, and anthropometrics
Results
In the validation dataset, the model that included serum creatinine, serum cystatin C, age, gender, and race was the most parsimonious and similarly predictive of mGFR compared to a model additionally including bioelectrical impedance analysis phase angle, CRIC clinical center, and 24-hour urinary creatinine excretion. Specifically, the root mean square errors for the separate model were 0.207 vs. 0.202, respectively. The performance of the CRIC GFR estimating equation was most accurate among the subgroups of younger participants, men, non-blacks, non-Hispanics, those without diabetes, those with body mass index <30 kg/m2, those with higher 24-hour urine creatinine excretion, those with lower levels of high-sensitivity C-reactive protein, and those with higher mGFR.
Limitations
Urinary clearance of 125I-iothalamate is an imperfect measure of true GFR; cystatin C is not standardized to certified reference material; lack of external validation; small sample sizes limit analyses of subgroup-specific predictors.
Conclusions
The CRIC GFR estimating equation predicts measured GFR accurately in the CRIC cohort using serum creatinine and cystatin C, age, gender, and race. Its performance was best among younger and healthier participants.
doi:10.1053/j.ajkd.2012.04.012
PMCID: PMC3565578  PMID: 22658574
glomerular filtration rate (GFR); kidney function; GFR estimation
14.  Retinopathy and Chronic Kidney Disease in the Chronic Renal Insufficiency Cohort Study (CRIC) 
Archives of ophthalmology  2012;130(9):1136-1144.
Objectives
Retinal vascular and anatomic abnormalities caused by diabetes, hypertension, and other conditions can be observed directly in the ocular fundus and may reflect severity of chronic renal insufficiency. The purpose of this study was to investigate the association between retinopathy and chronic kidney disease (CKD).
Methods
In this observational, cross-sectional study, 2605 participants of the Chronic Renal Insufficiency Cohort (CRIC) study, a multi-center study of CKD, were offered participation. Non-mydriatic fundus photographs of the disc and macula in both eyes were obtained in 1936 of these subjects.
Photographs were reviewed in a masked fashion at a central photograph reading center using standard protocols. Presence and severity of retinopathy (diabetic, hypertensive or other) and vessel diameter caliber were assessed by trained graders and a retinal specialist using protocols developed for large epidemiologic studies. Kidney function measurements and information on traditional and non-traditional risk factors for decreased kidney function were obtained from the CRIC study.
Results
Greater severity of retinopathy was associated with lower estimated glomerular filtration rate (eGFR) after adjustment for traditional and non-traditional risk factors. Presence of vascular abnormalities usually associated with hypertension was also associated with lower eGFR. We found no strong direct relationship between eGFR and average arteriolar or venular calibers.
Conclusions
Our findings show a strong association between severity of retinopathy and its features and level of kidney function after adjustment for traditional and non-traditional risk factors for CKD, suggesting that retinovascular pathology reflects renal disease.
doi:10.1001/archophthalmol.2012.1800
PMCID: PMC3719171  PMID: 22965589
Retinopathy; Retinal Vascular Diameter; Chronic Kidney Disease
15.  Factors Associated With Depressive Symptoms and Use of Antidepressant Medications Among Participants in the Chronic Renal Insufficiency Cohort (CRIC) and Hispanic-CRIC Studies 
Background
Depressive symptoms are correlated with poor health outcomes in adults with chronic kidney disease (CKD). The prevalence, severity, and treatment of depressive symptoms and potential risk factors, including level of kidney function, in diverse populations with CKD have not been well studied.
Study Design
Cross-sectional analysis
Settings and Participants
Participants at enrollment into the Chronic Renal Insufficiency Cohort (CRIC) and Hispanic-CRIC (H-CRIC) Studies. CRIC enrolled Hispanics and non-Hispanics at seven centers from 2003-2007, and H-CRIC enrolled Hispanics at the University of Illinois from 2005-2008.
Measurement
Depressive symptoms measured by Beck Depression Inventory (BDI)
Predictors
Demographic and clinical factors
Outcomes
Elevated depressive symptoms (BDI >= 11) and antidepressant medication use
Results
Among 3853 participants, 28.5% had evidence of elevated depressive symptoms and 18.2% were using antidepressant medications; 30.8% of persons with elevated depressive symptoms were using antidepressants. The prevalence of elevated depressive symptoms varied by level of kidney function: 25.2% among participants with eGFR ≥ 60 ml/min/1.73m2, and 35.1% of those with eGFR < 30 ml/min/1.73m2. Lower eGFR (OR per 10 ml/min/1.73m2 decrease, 1.09; 95% CI, 1.03-1.16), Hispanic ethnicity (OR, 1.65; 95% CI, 1.12-2.45), and non-Hispanic black race (OR, 1.43; 95% CI, 1.17-1.74) were each associated with increased odds of elevated depressive symptoms after controlling for other factors. In regression analyses incorporating BDI score, while female sex was associated with a greater odds of antidepressant use, Hispanic ethnicity, non-Hispanic black race, and higher levels of urine albumin were associated with decreased odds of antidepressant use (p<0.05 for each).
Limitations
Absence of clinical diagnosis of depression and use of non-pharmacologic treatments
Conclusions
Although elevated depressive symptoms were common in individuals with CKD, use of antidepressant medications is low. African Americans, Hispanics, and individuals with more advanced CKD had higher odds of elevated depressive symptoms and lower odds of antidepressant medication use.
doi:10.1053/j.ajkd.2011.12.033
PMCID: PMC3378778  PMID: 22497791
16.  Intensive Blood-Pressure Control in Hypertensive Chronic Kidney Disease 
The New England journal of medicine  2010;363(10):918-929.
BACKGROUND
In observational studies, the relationship between blood pressure and end-stage renal disease (ESRD) is direct and progressive. The burden of hypertension-related chronic kidney disease and ESRD is especially high among black patients. Yet few trials have tested whether intensive blood-pressure control retards the progression of chronic kidney disease among black patients.
METHODS
We randomly assigned 1094 black patients with hypertensive chronic kidney disease to receive either intensive or standard blood-pressure control. After completing the trial phase, patients were invited to enroll in a cohort phase in which the blood-pressure target was less than 130/80 mm Hg. The primary clinical outcome in the cohort phase was the progression of chronic kidney disease, which was defined as a doubling of the serum creatinine level, a diagnosis of ESRD, or death. Follow-up ranged from 8.8 to 12.2 years.
RESULTS
During the trial phase, the mean blood pressure was 130/78 mm Hg in the intensive-control group and 141/86 mm Hg in the standard-control group. During the cohort phase, corresponding mean blood pressures were 131/78 mm Hg and 134/78 mm Hg. In both phases, there was no significant between-group difference in the risk of the primary outcome (hazard ratio in the intensive-control group, 0.91; P = 0.27). However, the effects differed according to the baseline level of proteinuria (P = 0.02 for interaction), with a potential benefit in patients with a protein-to-creatinine ratio of more than 0.22 (hazard ratio, 0.73; P = 0.01).
CONCLUSIONS
In overall analyses, intensive blood-pressure control had no effect on kidney disease progression. However, there may be differential effects of intensive blood-pressure control in patients with and those without baseline proteinuria. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases, the National Center on Minority Health and Health Disparities, and others.)
doi:10.1056/NEJMoa0910975
PMCID: PMC3662974  PMID: 20818902
17.  Validation of the Kidney Disease Quality of Life Short Form 36 (KDQOL-36™) US Spanish and English Versions in a Cohort of Hispanics with Chronic Kidney Disease 
Ethnicity & disease  2013;23(2):202-209.
Objective
Evaluate the reliability and validity of the Kidney Disease Quality of Life Short Form 36 (KDQOL-36™) in Hispanics with mild-to-moderate chronic kidney disease (CKD).
Design
Cross-sectional
Setting
Chronic Renal Insufficiency Cohort Study
Participants
420 Hispanic (150 English- and 270 Spanish-speakers), and 409 non-Hispanic White individuals, matched by age (mean 57 years), sex (60% male), kidney function (mean estimated glomerular filtration rate 36ml/min/1.73m2), and diabetes (70%).
Methods
To measure construct validity, we selected instruments, comorbidities, and laboratory tests related to at least one KDQOL-36™ subscale. Reliability was determined by calculating Cronbach’s alpha.
Results
Reliability of each KDQOL-36™ subscale [SF-12 Physical Component Summary (PCS) and Mental Component Summary (MCS), Symptoms/Problems, Burden of Kidney Disease and Effects of Kidney Disease] was very good (Cronbach’s alpha >0.8). Construct validity was supported by expected negative correlation between MCS scores and the Beck Depression Inventory in all three subgroups (r= −0.56 to −0.61, P<.0001). There was inverse correlation between the Symptoms/Problems subscale and the Patient Symptom Form (r= −0.70 to −0.77, P<.0001). We also found significant, positive correlation between the PCS score and a physical activity survey (r= +0.29 to +0.38, P≤.003); and between the PCS and MCS scores and the Kansas City Questionnaire (r= +0.31 to +0.64, P<.0001). Reliability and validity were similar across all racial/ethnic groups analyzed separately.
Conclusion
Our findings support the use of the KDQOL-36™ as a measure of HRQOL in this cohort of US Hispanics with CKD.
PMCID: PMC3651651  PMID: 23530302
Validation; Quality of Life; Hispanics
18.  Chronic Kidney Disease in United States Hispanics: A Growing Public Health Problem 
Ethnicity & disease  2009;19(4):466-472.
Hispanics are the fastest growing minority group in the United States. The incidence of end-stage renal disease (ESRD) in Hispanics is higher than non-Hispanic Whites and Hispanics with chronic kidney disease (CKD) are at increased risk for kidney failure. Likely contributing factors to this burden of disease include diabetes and metabolic syndrome, both are common among Hispanics. Access to health care, quality of care, and barriers due to language, health literacy and acculturation may also play a role. Despite the importance of this public health problem, only limited data exist about Hispanics with CKD. We review the epidemiology of CKD in US Hispanics, identify the factors that may be responsible for this growing health problem, and suggest gaps in our understanding which are suitable for future investigation.
PMCID: PMC3587111  PMID: 20073150
Chronic Kidney Disease; Hispanics; Health Care Disparities
19.  CKD in Hispanics: Baseline Characteristics From the CRIC (Chronic Renal Insufficiency Cohort) and Hispanic-CRIC Studies 
Background
Little is known regarding chronic kidney disease (CKD) in Hispanics. We compared baseline characteristics of Hispanic participants in the Chronic Renal Insufficiency Cohort (CRIC) and Hispanic-CRIC (H-CRIC) Studies with non-Hispanic CRIC participants.
Study Design
Cross-sectional analysis
Setting and Participants
Participants were aged 21–74 years with CKD using age-based glomerular filtration rate (eGFR) at enrollment into the CRIC/H-CRIC Studies. H-CRIC included Hispanics recruited at the University of Illinois from 2005–2008 while CRIC included Hispanics and non-Hispanics recruited at seven clinical centers from 2003–2007.
Factor
Race/ethnicity
Outcomes
Blood pressure, angiotensin-converting enzyme (ACE) inhibitor/angiotensin receptor blocker (ARB) use, CKD-associated complications
Measurements
Demographic characteristics, laboratory data, blood pressure, and medications were assessed using standard techniques and protocols
Results
Among H-CRIC/ CRIC participants, 497 were Hispanic, 1650 non-Hispanic Black, and 1638 non-Hispanic White. Low income and educational attainment were nearly twice as prevalent in Hispanics compared with non-Hispanics (p<0.01). Hispanics had self-reported diabetes (67%) more frequently than non-Hispanic Blacks (51%) and Whites (40%) (p<0.01). Blood pressure > 130/80 mmHg was more common in Hispanics (62%) compared with Blacks (57%) and Whites (35%) (p<0.05), and abnormalities in hematologic, metabolic, and bone metabolism parameters were more prevalent in Hispanics (p<0.05), even after stratifying by entry eGFR. Hispanics had the lowest receipt of ACE inhibitor/ARB among high-risk subgroups, including participants with diabetes, proteinuria, and blood pressure > 130/80 mmHg. Mean eGFR (ml/min/m2) was lower in Hispanics (39.6) than in Blacks (43.7) and Whites (46.2), while median proteinuria was higher in Hispanics (0.72 g/d) than in Blacks (0.24 g/d) and Whites (0.12 g/d) (p<0.01).
Limitations
Generalizability; observed associations limited by residual bias and confounding
Conclusions
Hispanics with CKD in CRIC/H-CRIC Studies are disproportionately burdened with lower socioeconomic status, more frequent diabetes mellitus, less ACE inhibitor/ARB use, worse blood pressure control, and more severe CKD and associated complications than their non-Hispanic counterparts.
doi:10.1053/j.ajkd.2011.05.010
PMCID: PMC3577064  PMID: 21705121
chronic kidney disease; Hispanics; epidemiology
20.  Progression of CKD in Hispanics: Potential Roles of Health Literacy, Acculturation, and Social Support 
Hispanics are the fastest growing minority group in the United States and, compared with non-Hispanic whites, have a higher incidence of end-stage renal disease (ESRD). Examining novel factors that may explain this disparity in progression of chronic kidney disease (CKD) in Hispanics is urgently needed. Interpersonal and patient-centered characteristics, including health literacy, acculturation, and social support have been shown to affect health outcomes in other chronic diseases. However, these characteristics have not been well studied in the context of CKD, particularly in relation to disease knowledge, attitudes, and behaviors. In this paper, we examine the potential roles of these factors upon CKD progression in Hispanics and propose targeted therapeutic interventions.
doi:10.1053/j.ajkd.2011.05.004
PMCID: PMC3144398  PMID: 21787982
Chronic kidney disease; Hispanics; health disparities; health literacy; acculturation; social support
21.  Health-related quality of life in Hispanics with chronic kidney disease 
Translational Research  2009;155(4):157-163.
Health-related quality of life (HRQOL) is an important patient-reported outcome that has gained attention in research and clinical practice. In recent years, reports of chronic kidney disease (CKD) have increased. However, not much information is available for Hispanics with CKD, a group whose rates of incidents are on the rise. This review discusses the measurement of HRQOL in CKD, with a particular focus on issues pertaining to Hispanics. Future research directions also are discussed.
doi:10.1016/j.trsl.2009.10.005
PMCID: PMC3386523  PMID: 20303462
22.  Symptoms Characteristic of Heart Failure among CKD Patients without Diagnosed Heart Failure 
Journal of cardiac failure  2011;17(1):17-23.
Background
Epidemiological studies typically diagnose heart failure (HF) at the time of hospitalization, and have not evaluated the prevalence of HF symptoms in CKD patients without a prior HF diagnosis.
Methods and Results
We modified the Kansas City Cardiomyopathy Questionnaire (KCCQ) to detect and quantify symptoms characteristic of HF (dyspnea, edema, and fatigue) among 2,883 CKD patients without diagnosed heart failure in the Chronic Renal Insufficiency Cohort (CRIC). The KCCQ is a 23-item instrument that quantifies the impact of dyspnea, fatigue and edema on physical, social, and emotional functions (scored 0–100). The median KCCQ score was 92, and 25% had KCCQ scores < 75. Compared with cystatin C-based eGFR >50ml/min/1.73m2 (reference), eGFR 40–50, 30–40, and <30 were independently associated with lower KCCQ scores (<75); adjusted odds ratios and (95% CI): 1.38 (1.06–1.78), 1.39 (1.09–1.82), and 2.15 (1.54–3.00), respectively. Lower hemoglobin (Hb) levels also had independent associations with KCCQ <75: Hb > 14 g/dL (reference), Hb 13–14 g/dL (1.03; 0.76–1.40), Hb 12–13 g/dL (1.41; 1.04–1.91), Hb 11–12 g/dL (1.56; 1.12–2.16); and Hb<11 g/dL (1.65; 1.15–2.37).
Conclusion
CKD patients without diagnosed HF have a substantial burden of symptoms characteristic of HF, particularly among those with lower eGFR and hemoglobin levels.
doi:10.1016/j.cardfail.2010.08.009
PMCID: PMC3011973  PMID: 21187260
hemoglobin; glomerular filtration rate
23.  Elevated depressive affect is associated with adverse cardiovascular outcomes among African Americans with chronic kidney disease 
Kidney international  2011;80(6):670-678.
This study was designed to examine the impact of elevated depressive affect on health outcomes among participants with hypertensive chronic kidney disease in the African-American Study of Kidney Disease and Hypertension (AASK) Cohort Study. Elevated depressive affect was defined by Beck Depression Inventory II (BDI-II) thresholds of 11 or more, above 14, and by 5-Unit increments in the score. Cox regression analyses were used to relate cardiovascular death/hospitalization, doubling of serum creatinine/end-stage renal disease, overall hospitalization, and all-cause death to depressive affect evaluated at baseline, the most recent annual visit (time-varying), or average from baseline to the most recent visit (cumulative). Among 628 participants at baseline, 42% had BDI-II scores of 11 or more and 26% had a score above 14. During a 5-year follow-up, the cumulative incidence of cardiovascular death/hospitalization was significantly greater for participants with baseline BDI-II scores of 11 or more compared with those with scores <11. The baseline, time-varying, and cumulative elevated depressive affect were each associated with a significant higher risk of cardiovascular death/hospitalization, especially with a time-varying BDI-II score over 14 (adjusted HR 1.63) but not with the other outcomes. Thus, elevated depressive affect is associated with unfavorable cardiovascular outcomes in African Americans with hypertensive chronic kidney disease.
doi:10.1038/ki.2011.153
PMCID: PMC3237701  PMID: 21633409
AASK (African American Study of Kidney Disease and Hypertension); cardiovascular events; chronic kidney disease; depression
24.  FGF23, PTH and Phosphorus Metabolism in the Chronic Renal Insufficiency Cohort 
Kidney international  2011;79(12):1370-1378.
Fibroblast growth factor 23 (FGF23) regulates phosphorus metabolism and is a strong predictor of mortality in dialysis patients. FGF23 has been proposed as an early biomarker of disordered phosphorus metabolism in earlier stages of chronic kidney disease (CKD), but data from large, well-characterized CKD cohorts are lacking. We measured FGF23 in baseline samples from 3,879 participants in the Chronic Renal Insufficiency Cohort study, a nationally representative, diverse CKD cohort with mean (± sd) estimated glomerular filtration rate (eGFR) of 42.8 ± 13.5 ml/min/1.73m2. Serum phosphate (3.7 ± 0.7 mg/dl) and parathyroid hormone (PTH; median 54, interquartile range [IQR] 35 – 89 pg/ml) levels were in the normal range, but FGF23 (median 145, IQR 96 – 239 RU/ml) was markedly greater than in healthy populations and increased significantly with decreasing eGFR. FGF23 excess, defined as ≥ 100 RU/ml, was more common than secondary hyperparathyroidism (≥ 65 pg/ml) and hyperphosphatemia (≥ 4.6 mg/dl) in all strata of eGFR, and the eGFR threshold at which the slope of FGF23 increased (57.8; 95%CI: 55.4 – 60.8 ml/min/1.73m2) was higher than the corresponding threshold for PTH (46.9; 95%CI: 45.5 – 51.4 ml/min/1.73m2). Thus, increased FGF23 is a common manifestation of CKD that develops earlier than increases in phosphate or PTH. These findings provide additional support for use of FGF23 as a sensitive early screening test to identify disordered phosphorus metabolism in CKD patients with normal serum phosphate levels.
doi:10.1038/ki.2011.47
PMCID: PMC3134393  PMID: 21389978
25.  Central Pulse Pressure in Chronic Kidney Disease: A CRIC Ancillary Study 
Hypertension  2010;56(3):518-524.
Central pulse pressure can be non-invasively derived using the radial artery tonometric methods. Knowledge of central pressure profiles has predicted cardiovascular morbidity and mortality in several populations of patients, particularly those with known coronary artery disease and those receiving dialysis. Few data exist characterizing central pressure profiles in patients with mild-moderate chronic kidney disease who are not on dialysis. We measured central pulse pressure cross-sectionally in 2531 participants in the Chronic Renal Insufficiency Cohort study to determine correlates of the magnitude of central pulse pressure in the setting of chronic kidney disease. Tertiles of central pulse pressure (CPP) were < 36 mmHg, 36–51 mmHg and > 51 mmHg with an overall mean (± S.D.) of 46 ± 19 mmHg. Multivariable regression identified the following independent correlates of central pulse pressure: age, gender, diabetes mellitus, heart rate (negatively correlated), glycosylated hemoglobin, hemoglobin, glucose and PTH concentrations. Additional adjustment for brachial mean arterial pressure and brachial pulse pressure showed associations for age, gender, diabetes, weight and heart rate. Discrete intervals of brachial pulse pressure stratification showed substantial overlap within the associated central pulse pressure values. The large size of this unique chronic kidney disease cohort provides an ideal situation to study the role of brachial and central pressure measurements in kidney disease progression and cardiovascular disease incidence.
doi:10.1161/HYPERTENSIONAHA.110.153924
PMCID: PMC2941985  PMID: 20660819
Elasticity; epidemiology; diabetic nephropathies; hemodynamics; gender

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