The KNOW-CKD Study: What we have learned about chronic kidney diseases

Abstract

As the nation's largest chronic kidney disease (CKD) cohort, the KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD) was established to investigate the clinical course, risk factors for progression, and adverse outcomes of CKD. From 2011 to 2016, the KNOW-CKD recruited 2,238 adult patients with CKD from stage G1 to G5 who were not receiving renal replacement therapy from nine tertiary care hospitals throughout Korea. As of 2019, the KNOW-CKD has published more than 50 articles in the areas of socio-economics, nutrition, quality of life, health-related habits, CKD progression, cardiovascular comorbidity and outcome, anemia, mineral bone disease, biomarker discovery, and international and inter-ethnic comparisons. The KNOW-CKD will eventually offer a prediction model for long-term consequences of CKD, such as the occurrences of end-stage renal disease, cardiovascular disease, and death, thereby enabling the identification and treatment of at-risk populations that require extra medical attention.

Keywords: Chronic kidney disease; Cohort studies; Korea; Outcome.

Figure 1. Incidences of major outcomes of KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD) and comparison with the Chronic Renal Insufficiency Cohort (CRIC) cohort.

CRIC comprises CKD subjects with estimated glomerular filtration rate (eGFR) between 20 to 70 mL/min/1.73 m². Therefore, it is more relevant to compare CRIC and KNOW-CKD at stages G3a-5, rather than total KNOW-CKD subjects. ESRD, end-stage renal disease.

Figure 2. Adjusted Kaplan-Meier curve for cumulative renal events according to metabolic subtypes [40], reproduced with permission.

P < 0.001. MA, metabolic abnormality.

Figure 3. Association of measured 24-hour urinary sodium excretion with hazard ratio of chronic kidney disease progression in fully-adjusted model [41].

Note the relatively linear relationship between measured 24-hour urinary sodium excretion and risk of composite renal outcomes at the reference of urinary sodium excretion ≥ 120 mEq/day.

Figure 4. The association between high-sensitivity troponin T (hs-TnT) and longitudinal echocardiographic changes [61].

(A) Left ventricular hypertrophy: adjusted to age, sex, mean arterial pressure, diabetes mellitus (DM), hypertension (HTN), coronary artery disease, chronic kidney disease (CKD) stage, body mass index (BMI), high density lipoprotein cholesterol (HDL-C), triglyceride (TG), hemoglobin. (B) Diastolic dysfunction: adjusted to age, sex, DM, HTN, CKD stage, BMI, HDL-C, TG, C-reactive protein, smoking history.

Figure 5. Adjusted incidence rates of all-cause death (A) and composite of estimated glomerular filtration rate (eGFR) halving or end-stage renal disease (ESRD) (B) across the International Network of Chronic Kidney Disease studies (iNET-CKD) [51], reproduced with permission.

Adjusted incidence rates were estimated through direct standardization using the total population from all study groups as the standard. Adjustments included age, sex, and eGFR at baseline. Individuals included were 18 years and older and had an eGFR assessment at baseline between 15 and 60 mL/min per 1.73 m². Cochran’s Q and I² statistics were estimated to assess heterogeneity in incidence rates across iNET-CKD studies. AUS, Australia; CI, confidence interval; CAN, Canada; CAN-PREDDICT, Canadian Study of Prediction of Death, Dialysis and Interim Cardiovascular Events; CKD-JAC, Chronic Kidney Disease Japan Cohort; CKD-QLD, Chronic Kidney Disease in Queensland; CRIC, Chronic Renal Insufficiency Study; GBR, Great Britain; JPN, Japan; KNOW-CKD, KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease; KOR, Republic of Korea; NRHP, National Renal Healthcare Program; RIISC, Renal Impairment in Secondary Care; URY, Uruguay; USA, United States of America.