Yong Lim Kim

Simultaneous detection of antibody binding and cytotoxicity in flow cytometry crossmatch for renal transplantation

The anti‐HLA antibody can be detected using either a complement‐dependent lymphocytotoxicity (CDC) assay or a flow cytometry crossmatch (FCXM) in renal transplantation. Discordant results are often obtained because the two methods detect different reaction phases between the donor lymphocytes and the recipient sera. This study was intended to confirm that antibody binding and cytotoxicity to the lymphocytes can be detected simultaneously in a single FCXM assay, cytotoxic FCXM.

Low prealbumin levels are independently associated with higher mortality in patients on peritoneal dialysis

Background Prealbumin, a sensitive marker for protein–energy status, is also known as an independent risk factor for mortality in hemodialysis patients. We investigated the impact of prealbumin on survival in incident peritoneal dialysis (PD) patients. Methods In total, 136 incident PD patients (mean age, 53.0 ± 15.8 years) between 2002 and 2007 were enrolled in the study. Laboratory data, dialysis adequacy, and nutritional parameters were assessed 3 months after PD initiation. Patients were classified into 2 groups according to prealbumin level: high prealbumin (≥ 40 mg/dL) and low prealbumin (< 40 mg/dL). Results The patients in the low-prealbumin group were older and had more comorbidities such as diabetes and cardiovascular diseases compared with the patients in the high-prealbumin group. Mean subjective global assessment scores were lower, and the high-sensitivity C-reactive protein levels were higher in the low-prealbumin group. Serum creatinine, albumin, and transferrin levels; percent lean body mass; and normalized protein catabolic rate were positively associated, whereas subjective global assessment scores and high-sensitivity C-reactive protein levels were negatively associated with prealbumin concentration. During the median follow-up of 49 months, patients in the lower prealbumin group had a higher mortality rate. Multivariate analysis revealed that prealbumin < 40 mg/dL (hazard ratio, 2.30; 95% confidence interval, 1.14–4.64) was an independent risk factor for mortality. In receiver operating characteristic curves, the area under the curve of prealbumin for mortality was the largest among the parameters. Conclusion Prealbumin levels were an independent and sensitive predictor for mortality in incident PD patients, showing a good correlation with nutritional and inflammatory markers.

Serum Gamma-Glutamyltransferase Levels Predict Mortality in Patients With Peritoneal Dialysis.

Abstract Serum gamma-glutamyltransferase (GGT) level has been considered marker of oxidative stress as well as liver function. Serum GGT level has been reported to be associated with the mortality in hemodialysis patients. However, it is not well established whether serum GGT level is associated with all-cause mortality in peritoneal dialysis (PD) patients. The aim of this study was to determine the association between serum GGT levels and all-cause mortality in PD patients. PD patients were included from the Clinical Research Center registry for end-stage renal disease cohort, a multicenter prospective observational cohort study in Korea. Patients were categorized into 3 groups by tertile of serum GGT levels as follows: tertile 1, GGTu200a<u200a16u200aIU/L; tertile 2, GGTu200a=u200a16 to 27u200aIU/L; and tertile 3, GGTu200a>u200a27u200aIU/L. Primary outcome was all-cause mortality. A total of 820 PD patients were included. The median follow-up period was 34 months. Kaplan–Meier analysis showed that the all-cause mortality rate was significantly different according to tertiles of GGT (Pu200a=u200a0.001, log-rank). The multivariate Cox regression analysis showed that higher tertiles significantly associated with higher risk for all-cause mortality (tertile 2: hazard ratio [HR] 2.08, 95% confidence interval [CI], 1.17–3.72, Pu200a=u200a0.013; tertile 3: HR 1.83, 95% CI, 1.04–3.22, Pu200a=u200a0.035) in using tertile 1 as the reference group after adjusting for clinical variables. Our study demonstrated that high serum GGT levels were an independent risk factor for all-cause mortality in PD patients. Our findings suggest that serum GGT levels might be a useful biomarker to predict all-cause mortality in PD patients.

Comparison of Outcomes with Arteriovenous Fistula and Arteriovenous Graft for Vascular Access in Hemodialysis: A Prospective Cohort Study

Background: Poor vessel quality and limited life expectancy in the elderly may make arteriovenous fistula (AVF) less ideal than arteriovenous graft (AVG) or catheter for vascular access (VA) in hemodialysis (HD). Methods: A total of 946 adult incident HD patients from clinical research center registry for end-stage renal disease prospective cohort in South Korea were analyzed for outcomes with AVF and AVG. Results: Overall, AVF was associated with better patient survival only in male (p < 0.001) and diabetic (p = 0.004) patients, although it was superior to AVG in access patency, regardless of diabetes mellitus status and gender. AVG (vs. AVF; hazard ratio (HR) 2.282; 95% CI 1.071-4.861; p = 0.032) was associated with poor patient survival. In elderly patients (≥65 years), AVF was associated with survival benefit only in male (p < 0.001) and diabetic (p = 0.04) patients, and with better access patency only in female (p = 0.05) and diabetic (p = 0.04) patients. AVG (vs. AVF; HR 3.158; 95% CI 1.080-9.238; p = 0.036) was associated with poor patient survival. In septuagenarian patients, AVF was associated only with survival benefit (p = 0.01) and there was no advantage in access patency (p = 0.12). However, AVF was superior to AVG in both access patency (p = 0.001) and patient survival (p = 0.03) even with propensity matching. Conclusion: AVF is the more desirable VA and its survival benefits warrant its consideration in septuagenarian patients although a prolonged life expectancy is essential to realize the potential benefits of AVF.

Serum β2-Microglobulin Predicts Mortality in Peritoneal Dialysis Patients: A Prospective Cohort Study

Background/Aims: β2-Microglobulin (β2-M) is a surrogate marker of middle-molecule uremic toxins and is associated with mortality in chronic hemodialysis patients. However, the impact of serum β2-M levels on mortality in peritoneal dialysis (PD) patients is uncertain. The purpose of this study was to examine the association of serum β2-M levels with all-cause mortality in PD patients. Methods: A total of 771 PD patients were selected from the Clinical Research Center registry for end-stage renal disease cohort in Korea. Patients were categorized into 3 groups by tertiles of serum β2-M levels. The primary outcome was all-cause mortality. Results: The median value of serum β2-M was 23.6 mg/l (interquartile range 14.8-33.4 mg/l), and the median follow-up period was 39 months. The Kaplan-Meier analysis showed that the all-cause mortality rate was significantly different according to tertiles of serum β2-M in PD patients (p = 0.03, log-rank). Multivariate Cox proportional analysis showed that the hazards ratio for all-cause mortality was 1.02 (95% CI 1.01-1.04, p = 0.006) per 1 mg/l increase in β2-M after adjustment for multiple confounding factors that relate to malnutrition and inflammation marker. However, serum β2-M was not associated with all-cause mortality after adjustment for residual renal clearance. Conclusions: These results are supportive of the potential role of the serum β2-M level as a predictor of mortality in PD patients.

Lower serum potassium associated with increased mortality in dialysis patients: A nationwide prospective observational cohort study in Korea

Background Abnormal serum potassium concentration has been suggested as a risk factor for mortality in patients undergoing dialysis patients. We investigated the impact of serum potassium levels on survival according to dialysis modality. Methods A nationwide, prospective, observational cohort study for end stage renal disease patients has been ongoing in Korea since August 2008. Our analysis included patients whose records contained data regarding serum potassium levels. The relationship between serum potassium and mortality was analyzed using competing risk regression. Results A total of 3,230 patients undergoing hemodialysis (HD, 64.3%) or peritoneal dialysis (PD, 35.7%) were included. The serum potassium level was significantly lower (P < 0.001) in PD (median, 4.5 mmol/L; interquartile range, 4.0–4.9 mmol/L) than in HD patients (median, 4.9 mmol/L; interquartile range, 4.5–5.4 mmol/L). During 4.4 ± 1.7 years of follow-up, 751 patients (23.3%) died, mainly from cardiovascular events (n = 179) and infection (n = 120). In overall, lower serum potassium level less than 4.5 mmol/L was an independent risk factor for mortality after adjusting for age, comorbidities, and nutritional status (sub-distribution hazard ratio, 1.30; 95% confidence interval 1.10–1.53; P = 0.002). HD patients showed a U-shaped survival pattern, suggesting that both lower and higher potassium levels were deleterious, although insignificant. However, in PD patients, only lower serum potassium level (<4.5 mmol/L) was an independent predictor of mortality (sub-distribution hazard ratio, 1.35; 95% confidence interval 1.00–1.80; P = 0.048). Conclusion Lower serum potassium levels (<4.5 mmol/L) occur more commonly in PD than in HD patients. It represents an independent predictor of survival in overall dialysis, especially in PD patients. Therefore, management of dialysis patients should focus especially on reducing the risk of hypokalemia, not only that of hyperkalemia.

The impact of high serum bicarbonate levels on mortality in hemodialysis patients

Background/Aims The optimal serum bicarbonate level is controversial for patients who are undergoing hemodialysis (HD). In this study, we analyzed the impact of serum bicarbonate levels on mortality among HD patients. Methods Prevalent HD patients were selected from the Clinical Research Center registry for End Stage Renal Disease cohort in Korea. Patients were categorized into quartiles according to their total carbon dioxide (tCO2) levels: quartile 1, a tCO2 of < 19.4 mEq/L; quartile 2, a tCO2 of 19.4 to 21.5 mEq/L; quartile 3, a tCO2 of 21.6 to 23.9 mEq/L; and quartile 4, a tCO2 of ≥ 24 mEq/L. Cox regression analysis was used to calculate the adjusted hazard ratio (HR) and confidence interval (CI) for mortality. Results We included 1,159 prevalent HD patients, with a median follow-up period of 37 months. Kaplan-Meier analysis revealed that the all-cause mortality was significantly higher in patients from quartile 4, compared to those from the other quartiles (p = 0.009, log-rank test). The multivariate Cox proportional hazard model revealed that patients from quartile 4 had significantly higher risk of mortality than those from quartile 1, 2 and 3, after adjusting for the clinical variables in model 1 (HR, 1.99; 95% CI, 1.15 to 3.45; p = 0.01) and model 2 (HR, 1.82; 95% CI, 1.03 to 3.22; p = 0.04). Conclusions Our data indicate that high serum bicarbonate levels (a tCO2 of ≥ 24 mEq/L) were associated with increased mortality among prevalent HD patients. Further effort might be necessary in finding the cause and correcting metabolic alkalosis in the chronic HD patients with high serum bicarbonate levels.

Early dialysis initiation does not improve clinical outcomes in elderly end-stage renal disease patients: A multicenter prospective cohort study

Background The optimal timing for initiating dialysis in end-stage renal disease (ESRD) is controversial, especially in the elderly. Methods 665 patients ≥65 years old who began dialysis from August 2008 to February 2015 were prospectively enrolled in the Clinical Research Center for End-Stage Renal Disease cohort study. Participants were divided into 2 groups based on the median estimated glomerular filtration rate at the initiation of dialysis. Propensity score matching (PSM) was used to compare the overall survival rate, cardiovascular events, Kidney Disease Quality of Life Short Form 36 (KDQOL-36) results, Karnofsky performance scale values, Beck’s depression inventory values, and subjective global assessments. Results The mean patient age was 72.0 years, and 61.7% of the patients were male. Overall, the cumulative survival rates were lower in the early initiation group, although the difference was not significant after PSM. Additionally, the survival rates of the 2 groups did not differ after adjusting for age, sex, Charlson comorbidity index and hemoglobin, serum albumin, serum calcium and phosphorus levels. Although the early initiation group showed a lower physical component summary score on the KDQOL-36 3 months after dialysis, the difference in scores was not significant 12 months after dialysis. Furthermore, the difference was not significant after PSM. The Karnofsky performance scale, Beck’s depression inventory, and subjective global assessments were not significantly different 3 and 12 months after dialysis initiation. Conclusions The timing of dialysis initiation is not associated with clinical outcomes in elderly patients with ESRD.

The impact of blood flow rate during hemodialysis on all-cause mortality

Background/Aims Inadequacy of dialysis is associated with morbidity and mortality in chronic hemodialysis (HD) patients. Blood flow rate (BFR) during HD is one of the important determinants of increasing dialysis dose. However, the optimal BFR is unclear. In this study, we investigated the impact of the BFR on all-cause mortality in chronic HD patients. Methods Prevalent HD patients were selected from Clinical Research Center registry for end-stage renal disease cohort in Korea. We categorized patients into two groups by BFR < 250 and ≥ 250 mL/min according to the median value of BFR 250 mL/min in this study. The primary outcome was all-cause mortality. Results A total of 1,129 prevalent HD patients were included. The number of patients in the BFR < 250 mL/min was 271 (24%) and in the BFR ≥ 250 mL/min was 858 (76%). The median follow-up period was 30 months. Kaplan-Meier analysis showed that the mortality rate was significantly higher in patients with BFR < 250 mL/min than those with BFR ≥ 250 mL/min (p = 0.042, log-rank). In the multivariate Cox regression analyses, patients with BFR < 250 mL/min had higher all-cause mortality than those with BFR ≥ 250 mL/min (hazard ratio, 1.66; 95% confidence interval, 1.00 to 2.73; p = 0.048). Conclusions Our data showed that BFR < 250 mL/min during HD was associated with higher all-cause mortality in chronic HD patients.

Comparison of uremic pruritus between patients undergoing hemodialysis and peritoneal dialysis.

Background Uremic pruritus is a common, but unpleasant, complication of end-stage renal disease. The uremic burden may differ between hemodialysis (HD) and peritoneal dialysis (PD) patients. This difference may also change the clinical characteristics of uremic pruritus between the 2 modalities. In this study, we investigated the uremic pruritus between patients on HD and PD. Methods A total of 425 HD and 223 PD patients from the Clinical Research Center registry in Korea were included. Patients were assessed for pruritus intensity, scratching activity, pruritus distribution, and frequency of pruritus-related sleep disturbance using the visual analog scale and questionnaire. Results The prevalence of uremic pruritus was higher in PD patients than that in HD patients (62.6% vs. 48.3%, P = 0.001). In the multivariable logistic analysis, PD treatment was significantly associated with the prevalence of uremic pruritus (odds ratio, 1.76; 95% confidence interval, 1.20–2.57, P = 0.004) after adjustment for clinical variables. The visual analog scale score, representing a subjective intensity of itchiness, was significantly higher in PD patients (PD 2.11 ± 2.32 vs. HD 1.65 ± 2.28, P = 0.013) compared with HD patients. The intensity of uremic pruritus was independently related with serum albumin levels (β = –0.143, P = 0.006) in HD patients and total weekly Kt/V (β = –0.176, P = 0.028) in PD patients. Conclusion Our data demonstrate the difference in prevalence, intensity, and risk factors of uremic pruritus between HD and PD patients. These findings suggest that careful consideration for uremic pruritus might be needed in end-stage renal disease patients according to the dialysis modality.