Background The prevalence of chronic kidney disease (CKD) is increasing in the United States, caused in part by older age and increasing prevalences of hypertension and type 2 diabetes. CKD is silent ...and undetected until advanced stages. The study of populations with earlier stages of kidney disease may improve outcomes of CKD. Methods The Kidney Early Evaluation Program (KEEP), a National Kidney Foundation program, is a targeted community-based health-screening program enrolling individuals 18 years and older with diabetes, hypertension, or family history of kidney disease, diabetes, or hypertension. Participants who had received transplants or were on regular dialysis treatment were excluded from this analysis. The National Health and Nutrition Examination Survey (NHANES) 1999-2004 was a nationally representative cross-sectional survey; participants were interviewed in their homes and/or received standardized medical examinations in mobile examination centers. Results Of the 61,675 KEEP participants, 16,689 (27.1%) were found to have CKD. In the NHANES sample of 14,632 participants, 2,734 (15.3%) had CKD. Older age, smoking, obesity, diabetes, hypertension, and cardiovascular disease were associated significantly with CKD in both KEEP and NHANES ( P < 0.05 for all). Of note, the likelihood for CKD in African Americans differed between KEEP (odds ratio, 0.81; P < 0.001) and NHANES (odds ratio, 1.10; P = 0.2). Conclusion A greater prevalence of CKD was detected in the KEEP screening than in the NHANES data. KEEP has the limitations common to population-screening studies and conclusions for population-attributable risk may be limited. The targeted nature of the KEEP screening program and the large sample size with clinical characteristics comparable to NHANES validates KEEP as a valuable cohort to explore health associations for the CKD and at-risk-for-CKD populations in the United States.
Background The National Kidney Foundation has recommended that the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation replace the Modification of Diet in Renal Disease (MDRD) Study ...equation. Before implementing this change in the Kidney Early Evaluation Program (KEEP), we compared characteristics of reclassified individuals and mortality risk predictions using the new equation. Methods Of 123,704 eligible KEEP participants, 116,321 with data available for this analysis were included. Glomerular filtration rate (GFR) was estimated using the MDRD Study (eGFRMDRD ) and CKD-EPI (eGFRCKD-EPI ) equations with creatinine level calibrated to standardized methods. Participants were characterized by eGFR category: >120, 90-119, 60-89, 45-59, 30-44, and <30 mL/min/1.73 m2 . Clinical characteristics ascertained included age, race, sex, diabetes, hypertension, coronary artery disease, congestive heart failure, cerebrovascular disease, peripheral vascular disease, and anemia. Mortality was determined over a median of 3.7 years of follow-up. Results The prevalence of eGFRCKD-EPI <60 mL/min/1.73 m2 was 14.3% compared with 16.8% using eGFRMDRD . Using eGFRCKD-EPI , 20,355 participants (17.5%) were reclassified to higher eGFR categories, and 3,107 (2.7%), to lower categories. Participants reclassified upward were younger and less likely to have chronic conditions, with a lower risk of mortality. A total of 3,601 deaths (3.1%) were reported. Compared with participants classified to eGFR of 45-59 mL/min/1.73 m2 using both equations, those with eGFRCKD-EPI of 60-89 mL/min/1.73 m2 had a lower mortality incidence rate (6.4 95% CI, 5.1-7.7 vs 18.5 95% CI, 17.1-19.9). Results were similar for all eGFR categories. Net reclassification improvement was 0.159 ( P < 0.001). Conclusions The CKD-EPI equation reclassifies people at lower risk of CKD and death into higher eGFR categories, suggesting more accurate categorization. The CKD-EPI equation will be used to report eGFR in KEEP.
Background Early identification of anemia of chronic kidney disease may be important for the development of preventive strategies. We compared anemia prevalence and characteristics in the National ...Kidney Foundation Kidney Early Evaluation Program (KEEP) and National Health and Nutrition Examination Survey (NHANES) 1999-2004 populations. Methods Clinical, demographic, and laboratory data were collected from August 2000 to December 31, 2006, from participants in KEEP, a community-based health-screening program targeting individuals 18 years and older with diabetes, hypertension, or family history of kidney disease, diabetes, or hypertension. Anemia was defined as hemoglobin level less than 13.5 g/dL for men and less than 12.0 g/dL for women (Kidney Disease Outcomes Quality Initiative KDOQI 2006) or less than 13.0 g/dL for men and less than 12.0 g/dL for women (World Health Organization WHO). Results In KEEP (n = 70,069), 68.3% of participants, and in NHANES (n = 17,061), 52% of participants, were women. African Americans represented 33.9% of the KEEP and 11.2% of the NHANES cohorts, and Hispanics comprised 12.4% of KEEP and 13.2% of NHANES. Using the KDOQI classification, anemia was present in 13.9% and 6.3% of KEEP and NHANES participants, whereas using the WHO classification, anemia was present in 11.8% and 5.3%, respectively. In adjusted analysis of KEEP data, KDOQI-defined anemia was significantly more likely in men (odds ratio OR, 1.30; 95% confidence interval CI, 1.23 to 1.37); this pattern was reversed when using WHO-defined anemia (OR, 0.68; 95% CI, 0.64 to 0.72). Adjusted odds of anemia were greater for African American than white KEEP participants (OR, 2.98; 95% CI, 2.80 to 3.16; OR, 3.00; 95% CI, 2.81 to 3.20 for KDOQI- and WHO-defined anemia, respectively). Conclusion Anemia was twice as common in the targeted KEEP chronic kidney disease screening program cohort than in the NHANES sample population. African Americans had a 3-fold increased likelihood of anemia compared with whites. Targeted screening can identify anemia in a high-risk population.
Background Diabetes is a leading cause of chronic kidney disease (CKD). Whether reclassification of CKD stages based on glomerular filtration rate estimated using the CKD Epidemiology Collaboration ...(CKD-EPI) equation versus the Modification of Diet in Renal Disease (MDRD) Study equation modifies estimates of prevalent risk factors across stages is unknown. Methods This is a cross-sectional analysis of data from the Kidney Early Evaluation Program (KEEP), a community-based health screening program targeting individuals 18 years and older with diabetes, hypertension, or a family history of diabetes, hypertension, or kidney disease. Of 109,055 participants, 68.2% were women and 31.8% were African American. Mean age was 55.3 ± 0.05 years. Clinical, demographic, and laboratory data were collected from August 2000 through December 2009. Glomerular filtration rate was estimated using the CKD-EPI and MDRD Study equations. Results CKD was present in 25.6% and 23.5% of the study population using the MDRD Study and CKD-EPI equations, respectively. Diabetes was present in 42.4% and 43.8% of participants with CKD, respectively. Prevalent risk factors for diabetes included obesity (body mass index >30 kg/m2 ), 44.0%; hypertension, 80.5%; cardiovascular disease, 23.2%; family history of diabetes, 55.9%; and dyslipidemia, 43.0%. In a logistic regression model after adjusting for age and other risk factors, odds for diabetes increased significantly compared with no CKD with each CKD stage based on the CKD-EPI equation and similarly with stages based on the MDRD Study equation. Using a CKD-EPI–adjusted model, ORs were: stage 1, 2.08 (95% CI, 1.90-2.27); stage 2, 1.86 (95% CI, 1.72-2.02); stage 3, 1.23 (95% CI, 1.17-1.30); stage 4, 1.69 (95% CI, 1.42-2.03); and stage 5, 2.46 (95% CI, 1.46-4.14). Conclusions Using the CKD-EPI equation led to a lower prevalence of CKD but to similar diabetes prevalence rates associated with CKD across all stages compared with the MDRD Study equation. Diabetes and other CKD risk factor prevalence was increased compared with the non-CKD population.
Background Diabetes mellitus is the leading cause of chronic kidney disease (CKD) and contributes to increased morbidity and mortality in the CKD population. Early diabetes identification through ...targeted screening programs is important for the development of preventive strategies. Methods This is a cross-sectional analysis of the National Kidney Foundation Kidney Early Evaluation Program (KEEP) data and National Health and Nutrition and Examination Survey (NHANES) 1999-2004 data. KEEP is a community-based health-screening program enrolling individuals 18 years or older with diabetes, hypertension, or family history of kidney disease, diabetes, or hypertension. Study participants were those identified as meeting these inclusion criteria. Participants who had received kidney transplants or were currently receiving dialysis therapy were excluded. Results Of 73,460 KEEP participants, 20,562 (28.0%) had diabetes compared with 1,545 of 17,049 (6.7%) NHANES participants. Age, obesity, high cholesterol level, hypertension, and cardiovascular disease distributions were similar for patients with diabetes in both populations, whereas women and African Americans were overrepresented in KEEP. The prevalence of diabetes in KEEP progressively increased with increasing stage of CKD, and this relationship persisted in subgroup analyses of older participants (age > 46 years), as well as in analyses stratified by sex, race, and other CKD risk factors: current tobacco use, obesity, hypertension, cardiovascular disease, and increased cholesterol level. KEEP participants with CKD who reported having diabetes were unlikely to have met target blood glucose levels (odds ratio, 0.71; 95% confidence interval, 0.66 to 0.77; P < 0.001). Reporting not having diabetes was associated with the likelihood of increased blood glucose levels (odds ratio, 1.28; 95% confidence interval, 1.16 to 1.41; P < 0.001). Conclusion KEEP is congruent with NHANES regarding a greater prevalence of diabetes in patients with CKD. As a targeted screening program, KEEP may represent a higher risk and more motivated patient population.
Hydrogels are useful materials as scaffolds for tissue engineering applications. Using hydrogels with additive manufacturing techniques has typically required the addition of techniques such as ...cross-linking or printing in sacrificial materials that negatively impact tissue growth to remedy inconsistencies in print fidelity. Thus, there is a need for bioinks that can directly print cell-laden constructs. In this study, agarose-based hydrogels commonly used for cartilage tissue engineering were compared to Pluronic, a hydrogel with established printing capabilities. Moreover, new material mixtures were developed for bioprinting by combining alginate and agarose. We compared mechanical and rheological properties, including yield stress, storage modulus, and shear thinning, as well as construct shape fidelity to assess their potential as a bioink for cell-based tissue engineering. The rheological properties and printability of agarose–alginate gels were statistically similar to those of Pluronic for all tests (p > 0.05). Alginate–agarose composites prepared with 5% w/v (3:2 agarose to alginate ratio) demonstrated excellent cell viability over a 28-day culture period (>∼70% cell survival at day 28) as well matrix production over the same period. Therefore, agarose–alginate mixtures showed the greatest potential as an effective bioink for additive manufacturing of biological materials for cartilage tissue engineering.
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