The progression and complications of chronic kidney disease should differ depending on the cause (C), glomerular filtration rate category (G), and albuminuria (A). The KNOW-CKD (KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease), which is a prospective cohort study, enrolls subjects with chronic kidney disease stages 1 to 5 (predialysis). Nine nephrology centers in major university hospitals throughout Korea will enroll approximately 2,450 adults with chronic kidney disease over a 5-year period from 2011 to 2015. The participating individuals will be monitored for approximately 10 years until death or until end-stage renal disease occurs. The subjects will be classified into subgroups based on the following specific causes of chronic kidney disease: glomerulonephritis, diabetic nephropathy, hypertensive nephropathy, polycystic kidney disease, and others. The eligible subjects will be evaluated at baseline for socio-demographic information, detailed personal/family history, office BP, quality of life, and health behaviors. After enrollment in the study, thorough assessments, including laboratory tests, cardiac evaluation and radiologic imaging, will be performed according to the standardized protocol. The biospecimen samples will be collected regularly. A renal event is defined by >50% decrease in estimated GFR (eGFR) from the baseline values, doubling of serum creatinine, or end-stage renal disease. The primary composite outcome consists of renal events, cardiovascular events, and death. As of September 2013, 1,470 adult chronic kidney disease subjects were enrolled in the study, including 543 subjects with glomerulonephritis, 317 with diabetic nephropathy, 294 with hypertensive nephropathy and 249 with polycystic kidney disease. As the first large-scale chronic kidney disease cohort study to be established and maintained longitudinally for up to 10 years, the KNOW-CKD will help to clarify the natural course, complication profiles, and risk factors of Asian populations with chronic kidney disease. No. NCT01630486 at http://www.clinicaltrials.gov .

Background: Urinary tract infection (UTI) occurs in 30%-50% of individuals with autosomal dominant polycystic kidney disease (ADPKD). However, the clinical relevance of asymptomatic pyuria in ADPKD patients remains unknown. Methods: We retrospectively reviewed medical records of 256 ADPKD patients who registered to the ADPKD clinic at Seoul National University Hospital from Aug 1999 to Aug 2010. We defined the asymptomatic pyuria as more than 5-9 white blood cells in high-power field with no related symptoms or signs of overt UTI. Patients were categorized into 2 groups depending on its duration and frequency: Group A included non-pyuria and transient pyuria patients; Group B included recurrent and persistent pyuria patients. The association between asymptomatic pyuria and both the development of overt UTI and the deterioration of renal function were examined. Results: With a mean follow-up duration of 65.3 months, 176 (68.8%) out of 256 patients experienced 681 episodes of asymptomatic pyuria and 50 episodes of UTI. The annual incidence of asymptomatic pyuria was 0.492 episodes/patient/year. The patients in group B showed female predominance (58.5% vs. 42.0%, P=0.01) and experienced an upper UTI more frequently (hazard ratio: 4.612, 95% confidence interval: 1.735-12.258; P=0.002, adjusted for gender and hypertension). The annual change in estimated glomerular filtration rate (ΔeGFR) was significantly larger in magnitude in group B than in group A (-2.7±4.56 vs. -1.17±5.8, respectively; P=0.01). Age and Group B found to be the independent variables for ΔeGFR and developing end-stage renal disease (16.0% vs. 4.3%, respectively; P=0.001). Conclusions: Chronic asymptomatic pyuria may increase the risk of developing overt UTI and may contribute to declining renal function in ADPKD.

Since both retinopathy and nephropathy are major diabetic microvascular complications, we investigated whether severity of diabetic retinopathy (DR) has adverse effects on renal function and albuminuria in the patients with type 2 diabetes mellitus (DM). We screened 2,197 adult patients with type 2 DM who had undergone fundus exam between August 2006 and February 2014. Among them, 1,592 subjects with available serial renal function and albuminuria measurement were included in the analysis. DR status was classified as no DR, non-proliferative DR (NPDR), and proliferative DR (PDR). The risk of CKD progression was assessed according to DR severity. A total of 384 (24.1%) had NPDR and 202 (12.7%) had PDR at either eye. The mean follow-up period was 5.6±2.1 years. DR was associated with lower body mass index, lower plasma hemoglobin, lower serum albumin level, longer duration of DM, poorer control of blood sugar, lower estimated glomerular filtration rate (eGFR), and greater amount of albuminuria. Interestingly, baseline DR severity was associated with faster renal function decline and greater albuminuria progression. In multivariate analysis, NPDR had 2.9 times and PDR had 16.6 times higher risk for CKD progression. Our findings showed that baseline DR severity is a prognostic factor for future CKD progression in type 2 DM patients. Therefore, clinicians must evaluate DR severity at the first visit and closely monitor renal function and albuminuria in the subjects with severe DR.

Significance Statement: Health care–associated infections during previous serious coronavirus epidemics resulted from human-to-human transmission in hemodialysis (HD) facilities. The authors analyzed the effect of a strategy of HD with cohort isolation on the secondary transmission of coronavirus disease 2019 (COVID-19) in HD facilities in Korea, which involves administering an immediate screening test for COVID-19 to all close contacts (patients on HD and health care workers) and strict maintenance of cohort isolation. Epidemiologic investigation and immediate screening tests across 11 HD centers identified 302 close contacts. HD with cohort isolation was maintained for a median of 14 days, and the transmission rate was 0.66% inside HD units. Clinical practice guidelines for HD with cohort isolation during COVID-19 outbreaks may successfully prevent secondary transmission through HD units. Background: Health care–associated infections during previous coronavirus epidemics involving severe acute respiratory syndrome and Middle East respiratory syndrome resulted from human-to-human transmission in hemodialysis (HD) facilities. The effect of a strategy of HD with cohort isolation—separate dialysis sessions for close contacts of patients with confirmed coronavirus disease 2019 (COVID-19)—on the prevention of secondary transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in HD units is unknown. Methods: Our multicenter cohort study of an HD with cohort isolation strategy enrolled close contacts of patients with confirmed COVID-19, including patients on HD and health care workers in HD units. Close contacts had been identified by epidemiologic investigation and tested negative on an immediate screening test for SARS-CoV-2. Results: As of March 14, 11 patients on HD and 7 health care workers from 11 HD centers were diagnosed as having COVID-19. The immediate screening test was performed in 306 people, and among them, 302 close contacts with negative test results were enrolled. HD with cohort isolation was performed among all close contacts for a median of 14 days in seven centers. During cohort isolation, nine patients showed symptoms but tested negative for SARS-CoV-2. Two health care workers in the HD units (0.66% of the total group) were diagnosed at the termination test for SARS-CoV-2. Conclusions: The transmission of COVID-19 can be controlled without closure of HD centers by implementing preemptive activities, including early detection with rapid testing, cohort isolation, collaboration between institutions, and continuous monitoring of infection. Our strategy and experience may provide helpful guidance for circumstances involving the rapid spread of infectious diseases such as COVID-19.

The role of hyperuricemia in disease progression of autosomal dominant polycystic kidney disease (ADPKD) has not been defined well. We investigated the association of serum uric acid (sUA) with renal function and the effect of hypouricemic treatment on the rate of renal function decline. This is a single-center, retrospective, observational cohort study. A total of 365 patients with ADPKD who had estimated glomerular filtration rate (eGFR) ≥ 15 mL/min/1.73 m² and who were followed up for > 1 year were included in our analysis. Hyperuricemia was defined by a sUA level of ≥ 7.0 mg/dL in male and ≥ 6.0 mg/dL in female or when hypouricemic medications were prescribed. Hyperuricemia was associated with reduced initial eGFR, independent of age, sex, hypertension, albuminuria, and total kidney volume. During a median follow-up period of over 6 years, patients with hyperuricemia showed a faster annual decline in eGFR (−6.3% per year vs. −0.9% per year, p = 0.008). However, after adjusting for age, sex, hypertension and initial eGFR, sUA was no longer associated with either annual eGFR decline or the development of ESRD. Among 53 patients who received hypouricemic treatment, the annual eGFR decline appeared to be attenuated after hypouricemic treatment (pretreatment vs. posttreatment: −5.3 ± 8. 2 vs. 0.2 ± 6.2 mL/min/1.73 m² per year, p = 0.001 by Wilcoxon signed-rank test). Although hyperuricemia was associated with reduced eGFR, it was not an independent factor for renal progression in ADPKD. However, the correction of hyperuricemia may attenuate renal function decline in some patients with mild renal insufficiency.

Hayne Cho Park, Do Hyoung Kim, Kyung Don Yoo, Yang-Gyun Kim, Sang-Ho Lee, Hye Eun Yoon, Dong Ki Kim, Seong Nam Kim, Myeong Sung Kim, Yoon Chul Jung, Yon Su Kim, Young-Ki Lee; The Korean Society of Nephrology COVID-19 Task Force Team. Kidney Res Clin Pract 2020;39:145-50. https://doi.org/10.23876/j.krcp.20.046