Yeong Hoon Kim

The Prevalence of Chronic Kidney Disease (CKD) and the Associated Factors to CKD in Urban Korea: A Population-based Cross-sectional Epidemiologic Study

Chronic kidney disease (CKD) is a worldwide problem. This study was designed to survey the prevalence and risk factors for CKD in Korea. The 2,356 subjects were selected in proportion to age, gender, and city. Subjects 35 yr of age or older were selected from 7 cities. Estimated glomerular filtration rate (eGFR) was calculated using the Modification of Diet in Renal Disease (MDRD) Study equation, with albuminuria defined as a urine albumin to creatinine ratio of 30 mg/g or more. The overall prevalence of CKD was 13.7%. The prevalences of CKD according to stage were 2.0% stage 1, 6.7% stage 2, 4.8% stage 3, 0.2% stage 4, and 0.0% stage 5. The prevalences of microalbuminuria and macroalbuminuria were 8.6% and 1.6%, respectively. The prevalence of eGFR less than 60 mL/min/1.73 m2 was 5.0%. Age, body mass index (BMI), hypertension, diabetes mellitus, systolic blood pressure (SBP), diastolic blood pressure (DBP), and fasting blood glucose were independent factors related to the presence of CKD. In conclusions, Korea, in which the prevalence of CKD is increasing, should prepare a policy for early detection and appropriate treatment of CKD. The present data will be helpful in taking those actions.

Association of genetic polymorphisms of interleukins with new-onset diabetes after transplantation in renal transplantation.

Background New-onset diabetes after transplantation (NODAT) is a serious metabolic complication. Although &bgr;-cell dysfunction is considered the main contributing factor in the development of NODAT, the precise pathogenesis has not been identified. Although several cytokines have been suggested to be involved in the inflammation of islet beta cells in diabetes mellitus, only rarely have studies examined &bgr;-cell dysfunction in NODAT. Therefore, we examined the association between NODAT and 18 single nucleotide polymorphisms (SNPs) located within the 10 genes of interleukins (IL) or their receptors, which might be related with &bgr;-cell dysfunction after kidney transplantation. Methods A total of 306 renal transplants recipients were included without a history of diabetes. We analyzed the association between NODAT development and a panel of 18 SNPs within 10 genes of IL or their receptors. Results In terms of allele frequencies, rs2069763*T (IL-2), rs1494558*A and rs2172749*C (IL-7R), and rs4819554*A (IL-17R) were significantly higher in patients with NODAT. Eleven SNPs among 18 (61.1%) were significantly associated with NODAT development after adjusting for age, sex, and tacrolimus usage. They include IL-1B (rs3136558), IL-2 (rs2069762), IL-4 (rs2243250, rs2070874), IL-7R (rs1494558, rs2172749), IL-17RE (rs1124053), IL-17R (rs2229151, rs4819554), and IL-17RB (rs1043261, rs1025689). Conclusions The data suggest that inflammation of islet &bgr; cells might play a crucial role in the pathogenesis of NODAT in renal transplantation recipients. In particular, significant variations of IL-7R, IL-17E, IL-17R, and IL-17RB, which was recently reported to be associated with type 1 diabetes mellitus, could be associated with the pathogenesis of NODAT in renal transplant recipients.

IDENTIFICATION OF COAGULASE-NEGATIVE STAPHYLOCOCCI ISOLATED FROM CONTINUOUS AMBULATORY PERITONEAL DIALYSIS FLUID USING 16S RIBOSOMAL RNA, tuf, AND SodA GENE SEQUENCING

♦ Introduction: Coagulase-negative staphylococcus (CoNS) is the most common pathogen in continuous ambulatory peritoneal dialysis (CAPD)–associated peritonitis. There is no well-organized, standardized database for CoNS, and few studies have used gene sequencing in reporting species distribution in CAPD peritonitis. In the present study, we used 3 housekeeping genes to evaluate the prevalence of CoNS isolated from CAPD peritonitis episodes and to estimate the accuracy of, and the characteristic differences between, these genes for species identification. ♦ Methods: All 51 non-duplicated CoNS isolates obtained from CAPD peritonitis between April 2006 and May 2008 were used. The strains were identified by polymerase chain reaction and by direct sequencing using the 16S ribosomal RNA (rRNA), tuf, and sodA genes. We determined species distribution, and using selected databases, we analyzed the characteristics and diagnostic utility of the individual genes for species identification. ♦ Results: In GenBank (National Institutes of Health, Bethesda, MD, USA), we found 49 type or reference strains for CoNS 16S rRNA, 17 for tuf, and 46 for sodA, and we used those data for sequence-similarity comparisons with CAPD isolates. Among our 51 strains, S. epidermidis (66.7%) was the most common, followed by S. haemolyticus (11.8%), S. warneri (7.8%), S. caprae (5.9%), S. capitis (3.9%), and S. pasteuri (2.0%). For 1 strain, different species results were obtained with each gene. The identification rates with 16S rRNA, sodA, and tuf gene sequencing were 84.0%, 96.0%, and 92.2% respectively. The discrimination capability of 16S rRNA gene was lower in a few individual species, and for the sodA gene, the percentage similarity to sequences from reference strains was also lower. The tuf gene had excellent identification capacity, but relatively few type strains are available in public databases. The 16S rRNA gene did not discriminate between S. caprae and S. capitis. The sodA gene showed a similarity rate that was lower than that for sequences of the 16S rRNA gene. The tuf type strain sequences for S. caprae and S. pasteuri are not available in public databases. ♦ Conclusions: The sodA, tuf, and 16S rRNA genes were very useful for CoNS identification. Each has its own characteristics of similarity, discriminative power, and inclusion in databases.

Effects of neutral pH and low-glucose degradation product-containing peritoneal dialysis fluid on systemic markers of inflammation and endothelial dysfunction: a randomized controlled 1-year follow-up study

BACKGROUND The local peritoneal effects of low-glucose degradation product (GDP)-containing peritoneal dialysis fluid (PDF) have been extensively described. However, the systemic effects of prolonged prescription of these solutions are unknown. This study aimed to evaluate the effects of neutral pH and low-GDP PDF on systemic inflammation and endothelial dysfunction markers in peritoneal dialysis (PD) patients. METHODS This is a multicenter, open labeled, randomized controlled trial including one hundred fifty-two patients initiating continuous ambulatory peritoneal dialysis for end-stage renal disease from seven centers in Korea. Participants were randomly allocated to conventional PDF (Stay safe®; Fresenius Medical Care, Bad Homburg, Germany) or low-GDP PDF (Balance®; Fresenius Medical Care) and were followed for 1 year. Primary outcome variable was the inflammation and endothelial dysfunction index (IEDI), a composite score derived from serum levels of soluble intercellular adhesion molecule (sICAM)-1, soluble vascular cellular adhesion molecule (sVCAM)-1 and high-sensitivity C-reactive protein (hs-CRP). sICAM-1, sVCAM-1, residual renal function (RRF), peritoneal membrane transport characteristics, ultrafiltration volume and nutritional parameters were measured as secondary outcome variables. RESULTS Of 152 patients randomized, 146 (low-GDP: conventional PDF, 79:67) patients entered the trial (46% male, 53% with diabetes mellitus). At 12-month follow-up, the low-GDP group had significantly lower levels of IEDI, sICAM-1 and sVCAM-1 compared to the conventional group; hs-CRP was not different between groups. Peritoneal transport characteristics, RRF, nutritional parameters, incidence of peritonitis and death-censored technique survival were not different between groups. CONCLUSION Neutral pH and low-GDP PDF likely produce fewer changes in markers of endothelial dysfunction compared to conventional PDF in incident PD patients.

Safety and efficacy of the early introduction of everolimus with reduced-exposure cyclosporine a in de novo kidney recipients.

Background Everolimus and cyclosporine A (CsA) exhibit synergistic immunosuppressive activity when used in combination. We examined the safety and efficacy of the use of everolimus with a cyclosporine-sparing strategy in de novo renal transplant recipients. Methods A comparative, parallel, randomized, open-label 1-year study has been performed in 148 patients from five transplant centers to compare the efficacy and tolerability of everolimus and reduced exposure CsA (the investigational group) or enteric-coated mycophenolate sodium and standard-exposure CsA (the control group) in combination with basiliximab and steroids. The eligible subjects were randomly assigned at 1 month after transplantation. Efficacy failure (biopsy-proven acute rejection, death, graft loss, or loss to follow-up), safety, and renal function were evaluated. Results One graft loss has been reported in the control group and no patient death were reported in either group. The incidence of biopsy-proven acute rejection until 12 months after transplantation of the investigational group was 7.5%, compared to 11.1% of the control group (P=0.565). The mean estimated glomerular filtration rates of the investigational group at 12 months after transplantation was significantly higher (68.1±16.8 ml/min/1.73 m2) than that of the control group (60.6±15.8 ml/min/1.73 m2; P=0.016). There was no significant difference (P>0.05) in the incidence of discontinuations and serious adverse events between the groups. Conclusion The results of this study provide the evidences that (1) the calcineurin inhibitor (CNI) minimization by the introduction of everolimus after 1-month posttransplantation keeps the incidences of acute rejection and addtional risks as low as the conventional immunosuppression; (2) it allows minimizing CNI exposure, consequently reducing CNI nephrotoxicity and preserving renal function.

Angiotensinogen polymorphisms and post-transplantation diabetes mellitus in Korean renal transplant subjects.

Background: Post-transplant diabetes mellitus (PTDM) is a common and serious metabolic complication. Genetic polymorphisms of angiotensin-converting enzyme (ACE) and angiotensinogen (AGT) genes have been reported to be related to diabetes mellitus and insulin sensitivity; however, the role of these genes in the development of PTDM is not known. For this purpose, we investigated the association of ACE and AGT genetic polymorphisms with PTDM. Methods: A total of 302 subjects without previously diagnosed diabetes who had received kidney transplants were included. One ACE single nucleotide polymorphism (SNP) (rs4291) and two AGT SNPs (rs 699 and rs 4762) were genotyped from genomic DNA with direct sequencing. Results: PTDM developed in 49 (16.2%) of 302 subjects. Subjects in the PTDM were older than those in the non-PTDM. There was a significant difference between the two groups in tacrolimus use (p=0.03). Of the three SNPs, the rs4762 of the AGT gene was significantly associated with the development of PTDM in the dominant models (p = 0.03) after adjusting for age and tacrolimus usage. Conclusions: AGT gene rs4762 polymorphisms may serve as genetic markers for the development of PTDM. The exact molecular mechanisms still need to be clarified.

Improved gastrointestinal symptoms and quality of life after conversion from mycophenolate mofetil to enteric-coated mycophenolate sodium in renal transplant patients receiving tacrolimus.

It is reported that a conversion from mycophenolate mofetil (MMF) to enteric-coated mycophenolate sodium (EC-MPS) relieves gastrointestinal (GI) symptom burden and improves health-related quality of life (HRQoL). However, it is unclear whether renal transplant recipients using tacrolimus receive the same benefit from the conversion. In this prospective, multi-center, open-label trial, patients were categorized into two groups by their GI symptom screening. Equimolar EC-MPS (n=175) was prescribed for patients with GI burdens; those with no complaints remained on MMF (n=83). Gastrointestinal Symptom Rating Scale (GSRS) and Gastrointestinal Quality of Life Index (GIQLI) were evaluated at baseline and after one month. Patients and physicians completed Overall Treatment Effect (OTE) at one month. EC-MPS-converted patients had worse GSRS and GIQLI scores at baseline than MMF-continued patients (all P<0.001). Significant improvements in GSRS and GIQLI scores were observed for EC-MPS-converted patients at one month, but MMF-continued patients showed worsened GSRS scores (all P<0.05). OTE scale indicated that EC-MPS patients improved in overall GI symptoms and HRQoL more than MMF patients did (P<0.001). In tacrolimus-treated renal transplant recipients with GI burdens, a conversion from MMF to EC-MPS improves GI-related symptoms and HRQoL.

Nutritional Status in Adults with Predialysis Chronic Kidney Disease: KNOW-CKD Study

Adverse changes in nutrition are prevalent and are strong indicators of adverse outcomes in patients with chronic kidney disease (CKD). The International Society of Renal Nutrition and Metabolism (ISRNM) proposed a common nomenclature and diagnostic criteria to identify protein-energy wasting (PEW) in CKD patients. We examined the nutritional status in 1,834 adults with predialysis CKD enrolled in the KoreaN cohort study for Outcome in patients With Chronic Kidney Disease (KNOW-CKD) study. As there was a need for further understanding of nutritional status and associated factors in CKD, we evaluated the prevalence and associated factors of PEW in adults with predialysis CKD. The prevalence of PEW was about 9.0% according to ISRNM criteria and tended to increase with advanced stage in predialysis CKD. Those who concurrently had PEW, inflammation, and CVD were a small proportion (0.4%). In multivariate logistic regression model, PEW was independently associated with estimated glomerular filtration rate (eGFR) (odds ratio [OR], 0.98; 95% confidence interval [CI], 0.96–0.99), total CO2 (OR, 0.93; 95% CI, 0.87–0.99), physical activity (OR, 0.43; 95% CI, 0.26–0.69), comorbid diabetes (OR, 1.68; 95% CI, 1.09–2.59), and high sensitivity C-reactive protein (hs-CRP) (OR, 1.03; 95% CI, 1.01–1.06). Our study suggests that PEW increases with advanced CKD stage. PEW is independently associated with renal function, low total CO2, low physical activity, comorbid diabetes, and increased hs-CRP in adults with predialysis CKD.

Association studies of cytochrome P450, family 2, subfamily E, polypeptide 1 (CYP2E1) gene polymorphisms with acute rejection in kidney transplantation recipients.

Recent studies have shown that single‐nucleotide polymorphisms (SNPs) are associated with allograft rejection in kidney transplantation recipients. We evaluated the possible association between SNPs of the cytochrome P450, family 2, subfamily E, polypeptide 1 (CYP2E1) gene, and acute rejection (AR) among renal transplant patients in a Korean population. We conducted a case–control association study in 63 AR and 284 non‐AR kidney transplant recipients. The SNPs of CYP2E1 were genotyped by direct sequencing. Recipient sex (p = 0.023) and the use of tacrolimus (p = 0.017) were significantly different between the two groups. The use of mycophenolate mofetil (MMF) and antibody induction therapy was significantly lower in the AR group. Multiple logistic regression models (codominant, dominant, recessive, and log‐additive models) adjusted by sex and type of immunosuppressive regimens were applied to determine the odds ratios (ORs), 95% confidence intervals (CIs), and p‐values. The rs2515641 of CYP2E1 showed significant differences between the AR patient group and non‐AR group (p = 0.003, OR = 2.55, 95% CI = 1.37–4.75 in the codominant 1 model; p = 0.002, OR = 2.61, 95% CI = 1.43–4.77 in the dominant model; p = 0.0035, OR = 2.13, 95% CI = 1.29–3.50 in the log‐additive model). The allele of the rs2515641 SNP also showed a significant association (p = 0.004, OR = 1.99, 95% CI = 1.24–3.21). This study suggests that the CYP2E1 polymorphism may be related to the development of AR in Korean kidney transplantation recipients.

The Prevalence and Management of Anemia in Chronic Kidney Disease Patients: Result from the KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD)

Anemia is a common and significant complication of chronic kidney disease (CKD). However, its prevalence and current management status has not been studied thoroughly in Korea. We examined the prevalence of anemia, its association with clinical and laboratory factors, and utilization of iron agents and erythropoiesis stimulating agents using the baseline data from the large-scale CKD cohort in Korea. We defined anemia when hemoglobin level was lower than 13.0 g/dL in males and 12.0 g/dL in females, or received by erythropoiesis stimulating agents. Overall prevalence of anemia was 45.0% among 2,198 non-dialysis CKD patients from stage 1 to 5. Diabetic nephropathy (DN) as a cause, CKD stages, body mass index (BMI), smoking, leukocyte count, serum albumin, iron markers, calcium, and phosphorus concentration were identified as independent risk factors for anemia. Considering the current coverage of Korean National Health Insurance System, only 7.9% among applicable patients were managed by intravenous iron agents, and 42.7% were managed by erythropoiesis stimulating agents.