Jiwon Ryu

Renal function and decline in functional capacity in older adults

BACKGROUND longitudinal relationship between renal function, disability and mortality has not been evaluated. OBJECTIVE we investigated the temporal association between renal function and disability, and aimed to identify the influence of disability on mortality according to renal function in a cohort of older Koreans. DESIGN/SETTING Korean Longitudinal Study on Health and Aging is a prospective, population-based cohort. SUBJECTS community-dwelling Koreans ≥65 years of age. MAIN OUTCOME MEASURES Korean version of activities of daily living (ADL), Instrumental activities of daily living (IADL) and all-cause mortality. RESULTS a total of 984 participants were followed for 5 years with a 70.9% participation rate. The participants were categorized into three groups according to their baseline estimated glomerular filtration rates (eGFRs) (Group I, ≥60; Group II, 45-59; and Group III, <45 ml/min/1.73 m(2)). Baseline eGFR was higher in participants who maintained functional status compared with participants who died or had disability at follow-up examination. The incidence of ADL/IADL decline was 13, 12.5 and 29.5% in participants who showed improvement, no change, and decline in renal function, respectively (P = 0.01). The hazard ratio for mortality in the subgroup with IADL disability was 1.87 (95% CI: 1.10-3.20, P = 0.022) in Group I, and 2.53 (95% CI: 1.57-4.09, P<0.001) in Groups II and III after adjustment. CONCLUSIONS impaired renal function was related to disability and ADL/IADL decline. The effect of ADL/IADL disability on mortality was more prominent in participants with impaired eGFR.

Incident Chronic Kidney Disease and Newly Developed Complications Related to Renal Dysfunction in an Elderly Population during 5 Years: A Community-Based Elderly Population Cohort Study

Background Few studies have evaluated the association between incident chronic kidney disease (CKD) and related complications, especially in elderly population. We attempted to verify the association between GFR and concurrent CKD complications and elucidate the temporal relationship between incident CKD and new CKD complications in a community-based prospective elderly cohort. Method We analyzed the available data from 984 participants in the Korean Longitudinal Study on Health and Aging. Participants were categorized into 6 groups according to eGFR at baseline examination (≥90, 75–89, 60–74, 45–59, 30–44, and <30 ml/min/1.73 m2). Result The mean age of study population was 76 ± 9.1 years and mean eGFR was 72.3 ± 17.0 ml/min/1.73 m2. Compared to eGFR group 1, the odds ratio (OR) for hypertension was 2.363 (95% CI, 1.299-4.298) in group 4, 5.191 (2.074-12.995) in group 5, and 13.675 (1.611-115.806) in group 6; for anemia, 7.842 (2.265-27.153) in group 5 and 13.019 (2.920-58.047) in group 6; for acidosis, 69.580 (6.770-715.147) in group 6; and for hyperkalemia, 19.177 (1.798-204.474) in group 6. Over a 5-year observational period, CKD developed in 34 (9.6%) among 354 participants with GFR ≥ 60 ml/min/1.73 m2 at basal examination. The estimated mean number of new complications according to analysis of co-variance was 0.52 (95% CI, 0.35–0.68) in subjects with incident CKD and 0.24 (0.19–0.29) in subjects without CKD (p = 0.002). Subjects with incident CKD had a 2.792-fold higher risk of developing new CKD complications. A GFR level of 52.4 ml/min/1.73 m2 (p = 0.032) predicted the development of a new CKD complication with a 90% sensitivity. Conclusion In an elderly prospective cohort, CKD diagnosed by current criteria is related to an increase in the number of concurrent CKD complications and the development of new CKD complications.

The Clinical Association of the Blood Pressure Variability with the Target Organ Damage in Hypertensive Patients with Chronic Kidney Disease

It is known that blood pressure variability (BPV) can independently affect target organ damage (TOD), even with normal blood pressure. There have been few studieson chronic kidney disease (CKD) patients. We evaluated the relationship between BPV and TOD in a cross-sectional, multicenter study on hypertensive CKD patients. We evaluated 1,173 patients using 24-hr ambulatory blood pressure monitoring. BPV was defined as the average real variability, with a mean value of the absolute differences between consecutive readings of systolic blood pressure. TOD was defined as left ventricular hypertrophy (LVH) (by the Romhilt-Estes score ≥4 in electrocardiography) and kidney injury (as determined from an estimated glomerular filtration rate [eGFR]<30 mL/min/1.73 m2 and proteinuria).The mean BPV of the subjects was 15.9±4.63 mmHg. BPV displayed a positive relationship with LVH in a univariate analysis and after adjustment for multi-variables (odds ratio per 1 mmHg increase in BPV: 1.053, P=0.006). In contrast, BPV had no relationship with kidney injury. These data suggest that BPV may be positively associated with LVH in hypertensive CKD patients. Graphical Abstract

Impact of Electronic Acute Kidney Injury (AKI) Alerts With Automated Nephrologist Consultation on Detection and Severity of AKI: A Quality Improvement Study

BACKGROUND Several electronic alert systems for acute kidney injury (AKI) have been introduced. However, their clinical benefits require further investigation. STUDY DESIGN Before-and-after quality improvement study. SETTING & PARTICIPANTS A tertiary teaching hospital in Korea, which adopted an AKI alert system on June 1, 2014. Before and after launch of the alert system, 1,884 and 1,309 patients with AKI were included in the usual-care and alert groups, respectively. QUALITY IMPROVEMENT PLAN Implementation of an AKI alert system through which clinicians could generate automated consultations to the nephrology division for all hospitalized patients. OUTCOMES Primary outcomes included overlooked AKI events, defined as not measuring the follow-up creatinine value, and the consultation pattern of clinicians. Secondary outcomes were severe AKI events; AKI recovery, defined based on the creatinine-based criterion; and patient mortality. MEASUREMENTS ORs for events of overlooked AKI, early consultation, and severe AKI were calculated with logistic regression. AKI recovery rate and patient mortality were assessed using Cox regression. RESULTS After introduction of the alert system, the odds of overlooked AKI events were significantly lower (adjusted OR, 0.40; 95% CI, 0.30-0.52), and the odds of an early consultation with a nephrologist were greater (adjusted OR, 6.13; 95% CI, 4.80-7.82). The odds of a severe AKI event was reduced after implementation of the alerts (adjusted OR, 0.75; 95% CI, 0.64-0.89). Furthermore, the likelihood of AKI recovery was improved in the alert group (adjusted HR, 1.70; 95% CI, 1.53-1.88). Mortality was not affected by the AKI alert system (adjusted HR, 1.07; 95% CI, 0.68-1.68). LIMITATIONS Possible unreported differences between the alert and usual-care groups. CONCLUSIONS Implementation of the AKI alert system was associated with beneficial effects in terms of an improved rate of recovery from AKI. Therefore, widespread adoption of such systems could be considered in general hospitals.

Proteinuria and hematuria are associated with acute kidney injury and mortality in critically ill patients: a retrospective observational study

BackgroundProteinuria and hematuria are both important health issues; however, the nature of the association between these findings and acute kidney injury (AKI) or mortality remains unresolved in critically ill patients.MethodsProteinuria and hematuria were measured by a dipstick test and scored using a scale ranging from a negative result to 3+ in 1883 patients admitted to the intensive care unit. AKI was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines. The odds ratios (ORs) for AKI and 3-year mortality were calculated after adjustment for multiple covariates according to the degree of proteinuria or hematuria. For evaluating the synergistic effect on mortality among proteinuria, hematuria, and AKI, the relative excess risk due to interaction (RERI) was used.ResultsProteinuria and hematuria increased the ORs for AKI: the ORs of proteinuria were 1.66 (+/−), 1.86 (1+), 2.18 (2+), and 4.74 (3+) compared with non-proteinuria; the ORs of hematuria were 1.31 (+/−), 1.58 (1+), 2.63 (2+), and 2.52 (3+) compared with non-hematuria. The correlations between the mortality risk and proteinuria or hematuria were all significant and graded (Ptrend < 0.001). There was a relative excess risk of mortality when both AKI and proteinuria or hematuria were considered together: the synergy indexes were 1.30 and 1.23 for proteinuria and hematuria, respectively.ConclusionsProteinuria and hematuria are associated with the risks of AKI and mortality in critically ill patients. Additionally, these findings had a synergistic effect with AKI on mortality.

Endoscopic vision-based tracking of multiple surgical instruments during robot-assisted surgery.

Robot-assisted cardiac surgeries are effective for operations in limited spaces. Enhancement in safety functions based on automatic tracking of surgical instrument position to prevent inadvertent harmful events as cardiac tissue perforation and instrument collisions can be meaningful augmentation to current robot surgery system. A vision based instrument tracking scheme as a core algorithm to implement such assistive functions has been developed in this study. Through a chain of computer vision techniques, including classification of metallic properties using k-means clustering and instrument movement tracking using similarity measure, Euclidean distance calculation, and Kalman filter algorithm, an automatic tracking scheme has been proposed and the implemented system showed satisfactory performance in tests using real robot-assisted surgery videos. Trajectory comparisons of automatically detected data and ground truth data obtained by manually locating the center of mass of each instrument were used to quantitatively validate the system. The developed algorithm could provide valuable information to clinicians for safer operation.

Serum anion gap is predictive of mortality in an elderly population

An elevated serum anion gap is known to be associated with hypertension, low cardiorespiratory fitness, and decreased renal function. We evaluated whether serum AG might be predictive of elderly mortality in a community-based cohort in Korea. We analyzed the available data from 862 elderly people in the Korean Longitudinal Study on Health and Aging. Over a 5-year observational period, 151/862 (17.5%) participants died, and a high albumin-adjusted anion gap (SAAG) was associated with an increased risk of all-cause mortality in unadjusted analyses (hazard ratio [HR], 1.96; 95% confidence interval [CI], 1.41-2.71) and fully adjusted analyses (HR, 1.77; 95% CI, 1.24-2.52), compared with a low SAAG group. The population attributable fraction of death due to high SAAG was 38.2% (95% CI 20.7-58.2%). In particular, the participants with high SAAG had higher cardiovascular and infection-related mortality rates than those with low SAAG (HR, 2.11; 95% CI, 1.06-4.19, and HR, 9.69; 95% CI, 1.12-83.4, respectively). High SAAG may be an independent predictor of mortality and is associated with higher cardiovascular and infection related mortality in the elderly.

Time points for obtaining representative values of 24-hour blood pressure in chronic kidney disease.

Background/Aims: Ambulatory blood pressure (BP) monitoring has been widely recommended for evaluating the status of BP, but is lacking in practicality. Determination of the specific time points for BP measurement that are representative of 24-hour mean BP could be useful and convenient in hypertensive patients with chronic kidney disease (CKD). Methods: A total of 1,317 patients for whom 24-hour ambulatory BP monitoring was performed were enrolled in a multicenter study on hypertensive CKD. We analyzed the time points at which systolic blood pressure (SBP) values exhibited the smallest differences from 24-hour mean SBP (mSBP). We included office mSBP and analyzed the relationships between SBPs at the office and the time points with the smallest differences from 24-hour mSBP using several methods. Results: The time points with the smallest differences from 24-hour mSBP were 7:00 AM, 2:00 PM, and 9:30 PM. In regression analysis, SBPs at 7:00 AM and 9:30 PM were better correlated with 24-hour mSBP than SBPs at 2:00 PM and the office. The proportions of patients with SBPs within 30% of 24-hour mSBP were higher at 7:00 AM and 9:30 PM. The best consistency between the uncontrolled hypertensive groups, defined as ≥ 135 mmHg of 24-hour mSBP and higher values of SBPs corresponding to 135 mmHg of 24-hour mSBP, were observed at the 7:00 AM and 9:30 PM time points. Conclusions: The specific time points for SBPs that correlated well with 24-hour mSBP in hypertensive CKD patients were 7:00 AM and 9:30 PM.

Vascular calcification and cardiac function according to residual renal function in patients on hemodialysis with urination

Background Vascular calcification is common and may affect cardiac function in patients with end-stage renal disease (ESRD). However, little is known about the effect of residual renal function on vascular calcification and cardiac function in patients on hemodialysis. Methods This study was conducted between January 2014 and January 2017. One hundred six patients with residual renal function on maintenance hemodialysis for 3 months were recruited. We used residual renal urea clearance (KRU) to measure residual renal function. First, abdominal aortic calcification score (AACS) and brachial-ankle pulse wave velocity (baPWV) were measured in patients on hemodialysis. Second, we performed echocardiography and investigated new cardiovascular events after study enrollment. Results The median KRU was 0.9 (0.3–2.5) mL/min/1.73m2. AACS (4.0 [1.0–10.0] vs. 3.0 [0.0–8.0], p = 0.05) and baPWV (1836.1 ± 250.4 vs. 1676.8 ± 311.0 cm/s, p = 0.01) were significantly higher in patients with a KRU < 0.9 mL/min/1.73m2 than a KRU ≥ 0.9 mL/min/1.73m2. Log-KRU significantly negatively correlated with log-AACS (ß = -0.29, p = 0.002) and baPWV (ß = -0.19, P = 0.05) after factor adjustment. The proportion of left ventricular diastolic dysfunction was significantly higher in patients with a KRU < 0.9 mL/min/1.73m2 than with a KRU ≥ 0.9 mL/min/1.73m2 (67.9% vs. 49.1%, p = 0.05). Patients with a KRU < 0.9 mL/min/1.73m2 showed a higher tendency of cumulative cardiovascular events compared to those with a KRU ≥ 0.9 ml/min/1.73m2 (P = 0.08). Conclusions Residual renal function was significantly associated with vascular calcification and left ventricular diastolic dysfunction in patients on hemodialysis.

Seropositive rate of the anti-hepatitis A immunoglobulin G antibody in maintenance hemodialysis subjects from two hospitals in Korea

Background/Aims Hepatitis A virus (HAV) is a self-limiting infectious disease, but 1% of subjects develop fulminant hepatitis. The prevalence of the anti-HAV immunoglobulin G (IgG) antibody in hemodialysis subjects in Korea remains unknown. The purpose of this study was to describe and compare the seropositive rate of anti-HAV antibody among hemodialysis subjects in two hospitals according to age group. Methods A total of 170 hemodialysis subjects were evaluated for the seropositive rate of the anti-HAV IgG antibody and its titer. Results Of the 170 maintenance hemodialysis subjects in two hospitals (Kangnam 92 vs. Chuncheon 78), 79 (46.5%) were male. The mean age was 53.2 years old, and 94.1% of the subjects were over 40 years old. The median vintage of hemodialysis was 29.0 months. Anti-HAV antibody was found in 163 subjects (95.9%), with no significant difference between the two areas (Kangnam 97.8% [n = 90] vs. Chuncheon 93.6% [n = 73]). Subjects younger than 40 years old showed a seropositive rate of 50%, while the seropositive rate increased with age for subjects aged 40 or older (p for trend < 0.001). Seropositive subjects from Kangnam showed a higher anti-HAV antibody titer than those from Chuncheon (median: Kangnam 14.2 vs. Chuncheon 11.7). Only age influenced seropositivity. The only factor that influenced the antibody level was the location of hospital (p < 0.001). Conclusions The seropositive rate of the anti-HAV antibody in hemodialysis subjects was 95%, which is similar to findings in the general population. Active immunization against hepatitis A is strongly recommended for hemodialysis subjects under 40 years of age after anti-HAV testing.