World Kidney Day 2014: CKD and the aging population

Mendelian randomization analysis revealed that albuminuria is the key factor affecting socioeconomic status in CKD patients

Previous studies indicate a strong correlation between the incidence of chronic kidney disease (CKD) and lower economic status. However, these studies often struggle to delineate a clear cause-effect relationship, leaving healthcare providers uncertain about how to manage kidney disease in a way that improves patients' financial outcomes. Our study aimed to explore and establish a causal relationship between CKD and socioeconomic status, identifying critical influencing factors. We utilized summary meta-analysis data from the CKDGen Consortium and UK Biobank. Genetic variants identified from these sources served as instrumental variables (IVs) to estimate the association between CKD and socioeconomic status. The presence or absence of CKD, estimated glomerular filtration rate (eGFR), and albuminuria were used as exposures, while income and regional deprivation were analyzed as outcomes. We employed the R packages 'TwoSampleMR' and 'Mendelianrandomization' to conduct both univariable and multivariable Mendelian randomization (MR) analyses, assessing for potential pleiotropy and heterogeneity. Our univariable MR analysis revealed a significant causal relationship between high levels of albuminuria and lower income (OR = 0.84, 95% CI: 0.73-0.96, p = 0.013), with no significant pleiotropy detected. In the multivariable MR analysis, both CKD (OR = 0.867, 95% CI: 0.786-0.957, p = 0.0045) and eGFR (OR = 0.065, 95% CI: 0.010-0.437, p = 0.0049) exhibited significant effects on income. This study underscores that higher albuminuria levels in CKD patients are associated with decreased income and emphasizes the importance of effective management and treatment of albuminuria in CKD patients to mitigate both social and personal economic burdens.

Association of nocturia of self-report with estimated glomerular filtration rate: a cross-sectional study from the NHANES 2005-2018

Nocturia is a manifestation of systemic diseases, in which chronic kidney disease (CKD) is an independent predictor of nocturia due to its osmotic diuretic mechanism. However, to our knowledge, previous studies have not examined the association between nocturia and estimated glomerular filtration rate (eGFR). The purpose of this study was to assess the association between nocturia exposure and eGFR in the general US population. This study presents a cross-sectional analysis of the general US population enrolled in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2018. To account for potential confounding factors, linear regression analysis was conducted to investigate the association between nocturia and eGFR. Stratified analyses and interaction tests were employed to examine the variables of interest. Additionally, sensitivity analyses were conducted across diverse populations. A total of 12,265 individuals were included in the study. After controlling for confounding factors, the results of the linear regression analysis indicated that a single increase in nocturnal voiding frequency was associated with a decrease in eGFR by 2.0 mL/min/1.73 m2. In comparison to individuals with a nocturnal urinary frequency of 0, those who voided 1, 2, 3, 4, and ≥ 5 times at night experienced a decrease in eGFR by 3.1, 5.4, 6.4, 8.6 and 4.0 mL/min/1.73 m2, respectively. Nocturia was found to be associated with a decreased eGFR of 4 mL/min/1.73 m2 when compared to individuals without nocturia. The sensitivity analysis yielded consistent findings regarding the association between nocturia and eGFR in both CKD and non-CKD populations, as well as in hypertensive and non-hypertensive populations. Nevertheless, inconsistent conclusions were observed across various prognostic risk populations within the CKD context. The presence of nocturia and heightened frequency of nocturnal urination have been found to be associated with a decline in eGFR.

Polypharmacy, chronic kidney disease, and incident fragility fracture: a prospective cohort study

INTRODUCTION

Polypharmacy is associated with an increased risk of fracture in aging populations, but no study has accounted for the impact of kidney function on this association. This study aimed to examine the association between polypharmacy and incident fragility fracture based on chronic kidney disease (CKD) status.

MATERIALS AND METHODS

Participants were 2023 patients (55% men; mean age, 69 years) of Sado General Hospital enrolled in the Project in Sado for Total Health (PROST) between June 2008 and December 2016. Among these, 65%, 28%, and 7% had non-CKD, non-dialysis-dependent CKD, and dialysis-dependent CKD, respectively. Multivariable Cox proportional hazards analysis was conducted with adjustments for potential confounders.

RESULTS

Prevalences of polypharmacy (≥ 5 medications) and hyperpolypharmacy (≥ 10 medications) among participants were 43% and 9% for non-CKD, 62% and 23% for non-dialysis-dependent CKD, and 85% and 34% for dialysis-dependent CKD, respectively. During a median follow-up of 5.6 years, 256 fractures occurred. More medications were associated with a higher risk of fractures. Specifically, compared to participants without polypharmacy, adjusted hazard ratios were 1.32 (95% CI 0.96-1.79) and 1.99 (1.35-2.92) for those with polypharmacy and hyperpolypharmacy, respectively, after adjusting for osteoporosis risk factors, CKD status, and comorbidities. No effect modification by CKD status was observed (interaction P = 0.51). Population-attributable fractions of hyperpolypharmacy for fracture were 9.9% in the total cohort and 42.1% in dialysis-dependent CKD patients.

CONCLUSION

Hyperpolypharmacy is associated with an increased risk of fragility fracture regardless of CKD status, and has a strong impact on incident fragility fractures in dialysis-dependent CKD patients.

A distinctive distribution of hypoxia-inducible factor-1α in cultured renal tubular cells with hypoperfusion simulated by coverslip placement

Chronic hypoxia in the renal tubulointerstitium plays a key role in the progression of chronic kidney disease (CKD). It is therefore important to investigate tubular hypoxia and the activity of hypoxia-inducible factor (HIF)-1α in response to hypoxia. Rarefaction of the peritubular capillary causes hypoperfusion in CKD; however, the effect of hypoperfusion on HIFs has rarely been investigated. We induced hypoperfusion caused by coverslip placement in human kidney-2 cells, and observed an oxygen gradient under the coverslip. Immunocytochemistry of HIF-1α showed a doughnut-shaped formation on the edge of a pimonidazole-positive area, which we named the "HIF-ring". The oxygen tension of the HIF-ring was estimated to be between approximately 4 mmHg and 20 mmHg. This result was not compatible with those of past research showing HIF-1α accumulation in the anoxic range with homogeneous oxygen tension. We further observed the presence of a pH gradient under a coverslip, as well as a shift of the HIF ring due to changes in the pH of the culture medium, suggesting that the HIF ring was formed by suppression of HIF-1α related to low pH. This research demonstrated that HIF-1α activation mimics the physiological state in cultured cells with hypoperfusion.

Risk of haematological events and preventive effect of folic acid in methotrexate users with chronic kidney disease and rheumatoid arthritis: Analysis of the Japanese Adverse Drug Event Report database

Although methotrexate (MTX) for rheumatoid arthritis (RA) sometimes causes severe haematological toxicities in users with chronic kidney disease (CKD), data are limited regarding the risk of these events and the preventive effect of folic acid. This study evaluated the risk of haematological toxicities and the efficacy of folic acid in MTX users with CKD using the Japanese Adverse Drug Event Report. In total, 5,648 oral MTX users with RA were identified, including 630 with haematological toxicities. MTX users with CKD had significantly increased risk of haematological toxicities compared with those without CKD when folic acid was not used (OR 3.72; 95% CI 2.87-4.81; P < 0.01). Multivariate logistic analysis showed that the risk of haematological toxicities was significantly decreased by only folic acid (OR 0.16; 95% CI 0.04-0.62; P < 0.01). This result provides useful information for preventing severe haematological toxicities in MTX users with CKD and RA.

The ageing kidney: Molecular mechanisms and clinical implications

As human life expectancy keeps increasing, ageing populations present a growing challenge for clinical practices. Human ageing is associated with molecular, structural, and functional changes in a variety of organ systems, including the kidney. During the ageing process, the kidney experiences progressive functional decline as well as macroscopic and microscopic histological alterations, which are accentuated by systemic comorbidities like hypertension and diabetes mellitus, or by preexisting or underlying kidney diseases. Although ageing per se does not cause kidney injury, physiologic changes associated with normal ageing processes are likely to impair the reparative capacity of the kidney and thus predispose older people to acute kidney disease, chronic kidney disease and other renal diseases. Mechanistically, cell senescence plays a key role in renal ageing, involving a number of cellular signaling mechanisms, many of which may be harnessed as international targets for slowing or even reversing kidney ageing. This review summarizes the clinical characteristics of renal ageing, highlights the latest progresses in deciphering the role of cell senescence in renal ageing, and envisages potential interventional strategies and novel therapeutic targets for preventing or improving renal ageing in the hope of maintaining long-term kidney health and function across the life course.

Identifying risk factors for chronic kidney disease stage 3 in adults with acquired solitary kidney from unilateral nephrectomy: a retrospective cohort study

Background

We aimed to examine the risk factors for chronic kidney disease (CKD) stage 3 among adults with ASK from unilateral nephrectomy.

Methods

We retrospectively collected data from adult patients with ASK between January, 2009 and January, 2019, identified from a tertiary hospital in China. The clinical data were compared between patients who developed CKD stage 3 and those who did not develop CKD stage 3 during follow-up.

Results

In total, 172 patients with ASK (110 men; median 58.0 years) were enrolled, with a median follow-up duration of 5.0 years. During follow-up, 91 (52.9%) and 24 (14.0%) patients developed CKD stage 3 and end-stage renal disease, respectively. Multiple regression analyses showed that age (odds ratio [OR] 1.076, 95% confidence interval [CI] 1.039–1.115, p < 0.001), diabetes (OR 4.401, 95% CI 1.693–11.44, p = 0.002), hyperuricemia (OR 2.733, 95% CI 1.104–6.764, p = 0.03), a history of cardiovascular disease (CVD) (OR 5.583, 95% CI 1.884–18.068, p = 0.002), and ASK due to renal tuberculosis (OR 8.816, 95% CI 2.92–26.62, p < 0.001) were independent risk factors for developing CKD stage 3 among patients with ASK.

Conclusions

Regular follow-up of renal function is needed among adult patients with ASK. Optimal management of diabetes, hyperuricemia, and CVD may reduce their risk of CKD stage 3, especially among those that undergo unilateral nephrectomy for renal tuberculosis.

Rejuvenation: Turning back the clock of aging kidney

Aging is inevitable in life. It is defined as impaired adaptive capacity to environmental or internal stresses with growing rates of disease and death. Aging is also an important risk factor for various kidney diseases such as acute kidney injury and chronic kidney disease. Patients older than 65 years have nearly 28% risk of failing recovery of kidney function when suffering from acute kidney injury. It is reported that more than a third of population aged 65 years and older have chronic kidney disease in Taiwan, and the occurrence of multiple age-related disorders is predicted to increase in parallel. Renal aging is a complex, multifactorial process characterized by many anatomical and functional changes. Several factors are involved in renal aging, such as loss of telomeres, cell cycle arrest, chronic inflammation, activation of renin-angiotensin system, decreased klotho expression, and development of tertiary lymphoid tissues. These changes can also be observed in many other different types of renal injury. Recent studies suggested that young blood may rejuvenate aged organs, including the kidneys. In order to develop new therapeutic strategies for renal aging, the mechanisms underlying renal aging and by which young blood can halt or reverse aging process warrants further study.

Chronic kidney disease with genitourinary tuberculosis: old disease but ongoing complication

BACKGROUND

Genitourinary tuberculosis (GUTB) is a type of extrapulmonary TB that exerts a deleterious effect on renal function by promoting renal calcification and ureteric stricture. Therefore, we investigated the risk factors for chronic kidney disease (CKD) in GUTB patients after the end of treatment.

METHODS

This retrospective study was conducted at a tertiary hospital in South Korea. Data from patients (>18 years of age) with GUTB were collected from January 2005 to July 2016. CKD was defined as a glomerular filtration rate <60 mL/min/1.73m2 after the end of treatment.

RESULTS

In total, 56 patients with GUTB (46.4% males; mean age 52.8 ± 16.6 years) were enrolled in the study. CKD developed in 11 (19.6%) patients and end-stage renal disease in 4 (7.1%). In a univariate analysis, older age (p = 0.029), microscopic haematuria (p = 0.019), proteinuria (p = 0.029), acute renal failure (ARF) (p < 0.001) and a positive polymerase chain reaction-based test result for TB in the urine (p = 0.030) were significantly associated with decreased renal function. In a multivariate analysis, ARF (odds ratio [OR], 54.31; 95% confidence interval [CI], 1.52-1944.00; p = 0.032) and old age (OR, 54.26; 95% CI, 1.52-1932.94; p = 0.028) were independent risk factors for CKD in GUTB patients.

CONCLUSIONS

ARF and old age were independent risk factors for CKD in GUTB patients. Therefore, in elderly GUTB patients with ARF at the time of diagnosis, regular follow-up of renal function should be performed even after the end of treatment.

Dietary acid load and chronic kidney disease in elderly adults: Protein and potassium intake

BACKGROUND

Dietary net endogenous acid production (NEAP), which represents total dietary load of nonvolatile acid, may affect kidney function. Estimated NEAP (eNEAP) is calculated indirectly by the ratio of protein and potassium intake. A few studies are available assessing the association between eNEAP and chronic kidney disease (CKD), and its relation to dietary protein and potassium intake in the elderly.

METHODS

A total 1,369 community-dwelling elderly Koreans in the Kangbuk Samsung Cohort Study (KSCS) were evaluated using a food frequency questionnaire (FFQ) and comprehensive health examination. We evaluated the association between eNEAP and the CKD. We also examined their relation to protein and potassium intake.

RESULTS

eNEAP was correlated with potassium intake (r = -0.410, P < 0.001), but was not correlated with protein intake (r = -0.004, P = 0.879). In a full multivariate adjustment for sociodemographic factors, dietary factors, and comorbidities, the participants with higher eNEAP quartiles (Q2, Q3, Q4) had higher odds of CKD compared to the lowest eNEAP quartile (Q1); OR (95% CI) were 1.47 (0.78-2.72), 1.66 (0.85-3.23), and 2.30 (1.16-4.60) respectively (P for trend = 0.019). The odds of CKD decreased for participants with higher potassium intake quartiles (Q2, Q3, Q4) compared to the lowest potassium intake quartile (Q1); OR (95% CI) were 0.52 (0.28-0.95), 0.50 (0.26-0.96), and 0.50 (0.21-0.99) respectively (P for trend = 0.050). Protein intake was not associated with CKD. The association between eNEAP and CKD was similar in subgroup analysis.

CONCLUSION

Dietary acid load was associated with CKD. Among the nutrients related to dietary acid load, potassium intake was negatively associated with CKD, but protein intake was not associated with CKD in elderly adults.

Perspectives on optimizing care of patients in multidisciplinary chronic kidney disease clinics

Purpose of review

To summarize a jointly held symposium by the Canadian Society of Nephrology (CSN), the Canadian Association of Nephrology Administrators (CANA), and the Canadian Kidney Knowledge Translation and Generation Network (CANN-NET) entitled “Perspectives on Optimizing Care of Patients in Multidisciplinary Chronic Kidney Disease (CKD) Clinics” that was held on April 24, 2015, in Montreal, Quebec.

Sources of information

The panel consisted of a variety of members from across Canada including a multidisciplinary CKD clinic patient (Randall Russell), nephrology fellow (Dr. David Collister), geriatrician (Dr. Josee Verdon), and nephrologists (Dr. Monica Beaulieu, Dr. Adeera Levin).

Findings

The objectives of the symposium were (1) to gain an understanding of the goals of care for CKD patients, (2) to gain an appreciation of different perspectives regarding optimal care for patients with CKD, (3) to examine the components required for optimal care including education strategies, structures, and tools, and (4) to describe a framework and metrics for CKD care which respect patient and system needs. This article summarizes the key concepts discussed at the symposium from a patient and physician perspectives. Key messages include (1) understanding patient values and preferences is important as it provides a framework as to what to prioritize in multidisciplinary CKD clinic and provincial renal program models, (2) barriers to effective communication and education are common in the elderly, and adaptive strategies to limit their influence are critical to improve adherence and facilitate shared decision-making, (3) the use of standardized operating procedures (SOPs) improves efficiency and minimizes practice variability among health care practitioners, and (4) CKD scorecards with standardized system processes are useful in approaching variability as well as measuring and improving patient outcomes.

Limitations

The perspectives provided may not be applicable across centers given the differences in patient populations including age, ethnicity, culture, language, socioeconomic status, education, and multidisciplinary CKD clinic structure and function.

Implications

Knowledge transmission by collaborative interprovincial and interprofessional networks may play a role in facilitating optimal CKD care. Validation of system and clinic models that improve outcomes is needed prior to disseminating these best practices.

Descriptive study of the prevalence of anemia, hypertension, diabetes and quality of life in a randomly selected population of elderly subjects from São Paulo

BACKGROUND

The rapid increase in the aged population has resulted in a growing number of cases of chronic diseases. This increase is an important demographic change that low- and middle-income countries have to face and poses a new challenge to health services. One of the first steps to formulate public policies is to understand the reality of each country's aging population. This study describes the prevalence of anemia, hypertension and diabetes and the overall health status in pre-elderly and elderly subjects enrolled in two primary health care clinics, Eldorado and Piraporinha, in the city of Diadema, São Paulo.

METHOD

A cross-sectional study was conducted with 373 participants. Clinical data were collected from patient charts and the degree of disability and common mental disorders, as well as demographic data were obtained by interviews.

RESULTS

The prevalence of anemia was approximately 11% and hypertension was 70% and 81% in Eldorado and Piraporinha, respectively. The frequency of diabetes was 52% in Eldorado and 30% in Piraporinha. The subjects of both health care clinics reported having difficulties in some of their daily physical and instrumental activities, with physical symptoms and emotional disorders.

CONCLUSION

Anemia, hypertension and diabetes are prevalent in the studied population, and patients showed degrees of dependency and impaired health status.

The aging kidney: increased susceptibility to nephrotoxicity

Three decades have passed since a series of studies indicated that the aging kidney was characterized by increased susceptibility to nephrotoxic injury. Data from these experimental models is strengthened by clinical data demonstrating that the aging population has an increased incidence and severity of acute kidney injury (AKI). Since then a number of studies have focused on age-dependent alterations in pathways that predispose the kidney to acute insult. This review will focus on the mechanisms that are altered by aging in the kidney that may increase susceptibility to injury, including hemodynamics, oxidative stress, apoptosis, autophagy, inflammation and decreased repair.