Epidemiology of chronic kidney disease: think (at least) twice!

Low-Potassium Fruits and Vegetables: Research Progress and Prospects

With the increasing number of patients with chronic kidney disease (CKD) and the improved recognition of nutritional therapy, research on low-potassium (LK) fruits and vegetables for CKD patients has gained global attention. Despite its already commercial availability primarily in Japan, public awareness remains limited, and cultivation methods lack a comprehensive strategy. This review offers an extensive examination of the developmental significance, current cultivation techniques, and existing limitations of functional LK fruits and vegetables with the objective of providing guidance and inspiration for their exploitation. Additionally, this review investigates various factors influencing K content, including varieties, temperature, light, exogenous substances, harvest time, and harvest parts, with a focus on optimizing production methods to enhance potassium utilization efficiency (KUE) and decrease the K content in plants. Finally, the review outlines the shortcomings and prospects of research on LK fruits and vegetables, emphasizing the importance of interdisciplinary research (in agriculture technology, medicine, and business) for patients with CKD and the future development of this field.

Variations in Incidence and Prognosis of Stage 4 CKD Among Adults Identified Using Different Algorithms: A Population-Based Cohort Study

RATIONALE & OBJECTIVE

Clinical guidelines define chronic kidney disease (CKD) as abnormalities of kidney structure or function for>3 months. Assessment of the duration criterion may be implemented in different ways, potentially impacting estimates of disease incidence or prevalence in the population, individual diagnosis, and treatment decisions, especially for more severe cases. We investigated differences in incidence and prognosis of CKD stage G4 identified by 1 of 4 algorithms.

STUDY DESIGN

Population-based cohort study in Alberta, Canada.

SETTING & PARTICIPANTS

Residents>18 years old with incident CKD stage G4 (eGFR 15-29mL/min/1.73m2) diagnosed between April 1, 2015, and March 31, 2018, based on administrative and laboratory data.

EXPOSURE

Four outpatient eGFR-based algorithms, increasing in stringency, for defining cohorts with CKD G4 were evaluated: (1) a single test, (2) first eGFR<30mL/min/1.73m2 and a second eGFR 15-29mL/min/1.73m2 measured>90 days apart (2 tests), (3) ≥2 eGFR measurements of<30mL/min/1.73m2 sustained for>90 days (qualifying period) and the last eGFR in the qualifying period of 15-29mL/min/1.73m2 (relaxed sustained), and (4) ≥2 consecutive measurements of 15-29mL/min/1.73m2 for>90 days (rigorous sustained).

OUTCOME

Time to the earliest of death, eGFR improvement (a sustained increase in eGFR to≥30mL/min/1.73m2 for>90 days and>25% increase from the index eGFR), or kidney failure.

ANALYTICAL APPROACH

For each of the 4 cohorts, incidence rates and event-specific cumulative incidence functions at 1 year from cohort entry were estimated.

RESULTS

The incidence rates of CKD G4 decreased as algorithms became more stringent, from 190.7 (single test) to 79.9 (rigorous sustained) per 100,000 person-years. The 2 cohorts based on sustained reductions in eGFR were of comparable size and 1-year event-specific probabilities. The 2 cohorts based on a single test and a 2-test sequence were larger and experienced higher probabilities of eGFR improvement.

LIMITATIONS

A short follow-up period of 1 year and a predominantly White population.

CONCLUSIONS

The use of more stringent algorithms for defining CKD G4 results in substantially lower estimates of disease incidence, the identification of a group with a lower probability of eGFR improvement, and a higher risk of kidney failure. These findings can inform implementation decisions of disease definitions in clinical reporting systems and research studies.

PLAIN-LANGUAGE SUMMARY

Although guidelines recommend>3 months to define chronic kidney disease (CKD), the methods for defining specific stages, particularly G4 (eGFR 15-29mL/min/1.73m2) when referral to nephrology services is recommended, have been implemented differently across studies and surveillance programs. We studied differences in incidence and prognosis of CKD G4 cohorts identified by 4 algorithms using administrative and outpatient laboratory databases in Alberta, Canada. We found that, compared with a single-test definition, more stringent definitions resulted in a lower disease incidence and identified a group with worse short-term kidney outcomes. These findings highlight the impact of the choice of algorithm used to define CKD G4 on disease burden estimates at the population level, on individual prognosis, and on treatment/referral decisions.

Prevalence of chronic kidney disease in France: methodological considerations and pitfalls with the use of Health claims databases

Background

Health policy-making require careful assessment of chronic kidney disease (CKD) epidemiology to develop efficient and cost-effective care strategies. The aim of the present study was to use the RENALGO-EXPERT algorithm to estimate the global prevalence of CKD in France.

Methods

An expert group developed the RENALGO-EXPERT algorithm based on healthcare consumption. This algorithm has been applied to the French National Health claims database (SNDS), where no biological test findings are available to estimate a national CKD prevalence for the years 2018-2021. The CONSTANCES cohort (+219 000 adults aged 18-69 with one CKD-EPI eGFR) was used to discuss the limit of using health claims data.

Results

Between 2018 and 2021, the estimated prevalence in the SNDS increased from 8.1% to 10.5%. The RENALGO-EXPERT algorithm identified 4.5% of the volunteers in the CONSTANCES as CKD. The RENALGO-EXPERT algorithm had a positive predictive value of 6.2% and negative predictive value of 99.1% to detect an eGFR<60 ml/min/1.73 m². Half of 252 false positive cases (ALGO+, eGFR > 90) had been diagnosed with kidney disease during hospitalization, and the other half based on healthcare consumption suggestive of a 'high-risk' profile; 95% of the 1661 false negatives (ALGO-, eGFR < 60) had an eGFR between 45 and 60 ml/min, half had medication and two-thirds had biological exams possibly linked to CKD. Half of them had a hospital stay during the period but none had a diagnosis of kidney disease.

Conclusions

Our result is in accordance with other estimations of CKD prevalence in the general population. Analysis of diverging cases (FP and FN) suggests using health claims data have inherent limitations. Such an algorithm can identify patients whose care pathway is close to the usual and specific CKD pathways. It does not identify patients who have not been diagnosed or whose care is inappropriate or at early stage with stable GFR.

The relation between proteinuria and the severity of COVID-19

BACKGROUND

The association between proteinuria, which is also an indicator of chronic kidney disease (CKD), and coronavirus disease 2019 (COVID-19) severity is unclear.

METHODS

We selected 342 hospitalized patients with COVID-19 diagnosed via polymerase chain reaction testing between February 2020 and October 2022 and who had at least one urinalysis 14-365 days before admission.

RESULTS

Proteinuria before admission was associated neither with oxygen administration nor developing pneumonia in multivariate analysis (odds ratio [OR] 1.03; 95% confidence interval (CI) 0.44-2.40, p = 0.95 and OR 1.01; 95% CI 0.47-2.17, p = 0.98, respectively). Proteinuria on admission was associated both with oxygen administration and developing pneumonia in multivariate analysis (OR 3.29; 95% CI 1.37-7.88, p < 0.01 and OR 3.81; 95% CI 1.68-8.62, p < 0.01, respectively). The percentage of patients with proteinuria on admission was significantly higher than those before admission (37.4% vs. 17.8%; p < 0.01). In the subgroup analysis, proteinuria on admission among patients with eGFR ≥ 60 mL/min/1.73 m2 was associated with both oxygen administration and developing pneumonia (OR 4.86; 95% CI 1.22-19.38, p = 0.03, OR 3.65; 95% CI 1.06-12.58, p = 0.04, respectively). In contrast, proteinuria on admission among patients with eGFR < 60 mL/min/1.73 m2 was associated with developing pneumonia (OR 6.45; 95%CI 1.78-23.35, p = 0.01), not with oxygen administration (OR 3.28; 95% CI 0.92-11.72, p = 0.07).

CONCLUSIONS

Although underlying proteinuria before admission was not associated with COVID-19 severity, proteinuria on admission was associated with oxygen demand and developing pneumonia.

Impaired Renal Function and Major Cardiovascular Events in Young Adults

BACKGROUND

Cardiovascular (CV) disease in young adults (aged 18-39 years) is on the rise. Whether subclinical reductions in kidney function (ie, estimated glomerular filtration rate [eGFR] above the current threshold for chronic kidney disease but below age-expected values) are associated with elevated CV risk is unknown.

OBJECTIVES

The goal of this study was to examine age-specific associations of subclinical eGFR reductions in young adults with major adverse cardiovascular events (MACEs) and MACE plus heart failure (MACE+).

METHODS

A retrospective cohort study of 8.7 million individuals (3.6 million aged 18-39 years) was constructed using linked provincial health care data sets from Ontario, Canada (January 2008-March 2021). Cox models were used to examine the association of categorized eGFR (50-120 mL/min/1.73 m2) with MACE (first of CV mortality, acute coronary syndrome, and ischemic stroke) and MACE+, stratified according to age (18-39, 40-49, and 50-65 years).

RESULTS

In the study cohort (mean age 41.3 years; mean eGFR 104.2 mL/min/1.73 m2; median follow-up 9.2 years), a stepwise increase in the relative risk of MACE and MACE+ was observed as early as eGFR <80 mL/min/1.73 m2 in young adults (eg, for MACE, at eGFR 70-79 mL/min/1.73 m2, ages 18-30 years: 2.37 events per 1,000 person years [HR: 1.31; 95% CI: 1.27-1.40]; ages 40-49 years: 6.26 events per 1,000 person years [HR: 1.09; 95% CI: 1.06-1.12]; ages 50-65 years: 14.9 events per 1,000 person years [HR: 1.07; 95% CI: 1.05-1.08]). Results persisted for each MACE component and in additional analyses (stratifying according to past CV disease, accounting for albuminuria at index, and using repeated eGFR measures).

CONCLUSIONS

In young adults, eGFR below age-expected values were associated with an elevated risk for MACE and MACE+, warranting age-appropriate risk stratification, proactive monitoring, and timely intervention.

Associations between modest reductions in kidney function and adverse outcomes in young adults: retrospective, population based cohort study

OBJECTIVE

To study age specific associations of modest reductions in estimated glomerular filtration rate (eGFR) with adverse outcomes.

DESIGN

Retrospective, population based cohort study.

SETTING

Linked healthcare administrative datasets in Ontario, Canada.

PARTICIPANTS

Adult residents (18-65 years) with at least one outpatient eGFR value (categorized in 10 unit increments from 50 mL/min/1.73m2 to >120 mL/min/1.73m2), with no history of kidney disease.

MAIN OUTCOME MEASURES

eGFRs and hazard ratios of composite adverse outcome (all cause mortality, any cardiovascular event, and kidney failure) stratified by age (18-39 years, 40-49 years, and 50-65 years), and relative to age specific eGFR referents (100-110 mL/min/1.73m2) for ages 18-39 years, 90-100 for 40-49 years, 80-90 for 50-65 years).

RESULTS

From 1 January 2008 to 31 March 2021, among 8 703 871 adults (mean age 41.3 (standard deviation 13.6) years; mean index eGFR 104.2 mL/min/1.73m2 (standard deviation 16.1); median follow-up 9.2 years (interquartile range 5.7-11.4)), modestly reduced eGFR measurements specific to age were recorded in 18.0% of those aged 18-39, 18.8% in those aged 40-49, and 17.0% in those aged 50-65. In comparison with age specific referents, adverse outcomes were consistently higher by hazard ratio and incidence for ages 18-39 compared with older groups across all eGFR categories. For modest reductions (eGFR 70-80 mL/min/1.73m2), the hazard ratio for ages 18-39 years was 1.42 (95% confidence interval 1.35 to 1.49), 4.39 per 1000 person years; for ages 40-49 years was 1.13 (1.10 to 1.16), 9.61 per 1000 person years; and for ages 50-65 years was 1.08 (1.07 to 1.09), 23.4 per 1000 person years. Results persisted for each individual outcome and in many sensitivity analyses.

CONCLUSIONS

Modest eGFR reductions were consistently associated with higher rates of adverse outcomes. Higher relative hazards were most prominent and occurred as early as eGFR <80 mL/min/1.73m2 in younger adults, compared with older groups. These findings suggest a role for more frequent monitoring of kidney function in younger adults to identify individuals at risk to prevent chronic kidney disease and its complications.

The prevalence of chronic kidney disease in South Africa - limitations of studies comparing prevalence with sub-Saharan Africa, Africa, and globally

BACKGROUND

Chronic kidney disease (CKD) is a globally significant non-communicable disorder. CKD prevalence varies between countries and within a country. We compared the prevalence rates of CKD in South Africa with sub-Saharan Africa, Africa, and globally.

METHODS

We registered a systematic review with the International Prospective Register of Systematic Reviews for prevalence studies reporting CKD stages III-V from 2013 to 2021. The analysis sought to explain any significant differences in prevalence rates. The R statistical package was used for data analysis. Comparisons included measures of effect size due to the large sample sizes analysed. We also compared sex differences in prevalence rates, common aetiologies, and type of study methodologies employed.

RESULTS

Eight studies were analysed, with two from each region. The matched prevalence rates of CKD between the various regions and South Africa showed significant differences, except for one comparison between South Africa and an African study [p = 0.09 (95% CI - 0.04-0.01)]. Both sub-Saharan African studies had a higher prevalence than South Africa. One study in Africa had a higher prevalence, while the other had a lower prevalence, whilst one Global study had a higher prevalence, and the other had a lower prevalence compared to South Africa. The statistical differences analysed using the Cramer's V test were substantially less than 0.1. Thus, differences in comparisons were largely due to differences in sample sizes rather than actual differences.

CONCLUSION

Variable prevalence rates between regions included disparities in sample size, definitions of CKD, lack of chronicity testing and heterogeneous laboratory estimations of eGFR. Improved consistency and enhanced methods for diagnosing and comparing CKD prevalence are essential.

Defining measures of kidney function in observational studies using routine health care data: methodological and reporting considerations

The availability of electronic health records and access to a large number of routine measurements of serum creatinine and urinary albumin enhance the possibilities for epidemiologic research in kidney disease. However, the frequency of health care use and laboratory testing is determined by health status and indication, imposing certain challenges when identifying patients with kidney injury or disease, when using markers of kidney function as covariates, or when evaluating kidney outcomes. Depending on the specific research question, this may influence the interpretation, generalizability, and/or validity of study results. This review illustrates the heterogeneity of working definitions of kidney disease in the scientific literature and discusses advantages and limitations of the most commonly used approaches using 3 examples. We summarize ways to identify and overcome possible biases and conclude by proposing a framework for reporting definitions of exposures and outcomes in studies of kidney disease using routinely collected health care data.

Lifestyle-Related Risk Factors for the Incidence and Progression of Chronic Kidney Disease in the Healthy Young and Middle-Aged Population

The prevalence of chronic kidney disease (CKD) increased by 88% from 1990 to 2016. Age of onset of lifestyle-related diseases (such as hypertension, diabetes mellitus, obesity, dyslipidemia, and hyperuricemia), which are risk factors for incident CKD, is lower now compared with the past. Thus, we aimed to evaluate the risk factors for the incidence and progression of CKD in the young and middle-aged population. There are differences in the risk for CKD among the young, middle-aged, and elderly populations. We aimed to assess obesity (which is basic component of metabolic syndrome), waist circumference, and abdominal adiposity, which are predictive factors of CKD in the younger population. Furthermore, we described the management and clinical evidence of hypertension, diabetes mellitus, dyslipidemia, and hyperuricemia for young and middle-aged patients, along with diet management and nutrients associated with kidney function. Kidney function in the young and middle-aged population is mostly normal, and they are considered a low-risk group for incident CKD. Thus, we expect this review to be useful in reducing the prevalence of CKD.

Twenty years of real-world data to estimate chronic kidney disease prevalence and staging in an unselected population

Chronic kidney disease (CKD) represents a global public health burden, but its true prevalence is not fully characterized in the majority of countries. We studied the CKD prevalence in adult users of the primary, secondary and tertiary healthcare units of an integrated health region in northern Portugal (n = 136 993; representing ∼90% of the region's adult population). Of these, 45 983 (33.6%) had at least two estimated glomerular filtration rate (eGFR) assessments and 30 534 (22.2%) had at least two urinary albumin:creatinine ratio (UACR) assessments separated by at least 3 months. CKD was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines as a persistent decrease in eGFR (<60 ml/min/1.73 m²) and/or an increase in UACR (≥30 mg/g). The estimated overall prevalence of CKD was 9.8% and was higher in females (5.5%) than males (4.2%). From these, it was possible to stratify 4.7% according to KDIGO guidelines. The prevalence of CKD was higher in older patients (especially in patients >70 years old) and in patients with comorbidities. This is the first real-world-based study to characterize CKD prevalence in a large, unselected Portuguese population. It probably provides the nearest estimate of the true CKD prevalence and may help healthcare providers to guide CKD-related policies and strategies focused on prevention and on the improvement of cardiovascular disease and other outcomes.

Age and the Course of GFR in Persons Aged 70 and Above

BACKGROUND AND OBJECTIVES

In older adults, data on the age-related course of GFR are scarce, which might lead to misjudgment of the clinical relevance of reduced GFR in old age.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

To describe the course of eGFR in older adults and derive reference values in population-based individuals, we used the longitudinal design of the Berlin Initiative Study (BIS) with a repeated estimation of GFR over a median of 6.1 years of follow-up. In 2069 community-dwelling older individuals (mean inclusion age 80 years, range 70-99), GFR was estimated biennially with the BIS-2 equation, including standardized creatinine and cystatin C levels, sex, and age. We described the crude and adjusted course using a mixed-effects model and analyzed the influence of death on the GFR course applying joint models. GFR slopes were compared using GFR equations on the basis of creatinine and/or cystatin C.

RESULTS

We observed a decreasing, thus nonlinear, eGFR decline with increasing age in a population of old adults. The estimated 1-year slope for ages 75 and 90 diminished for men from -1.67 to -0.99 and for women from -1.52 to -0.97. The modeled mean eGFR for men aged ≥79 and women ≥78 was below 60 ml/min per 1.73 m². Multivariable adjustment attenuated slopes only minimally. Taking death into account by applying joint models did not alter the nonlinear eGFR decline. Using eGFR equations on the basis of creatinine only showed linear slope patterns in contrast to nonlinear patterns for equations including cystatin C.

CONCLUSIONS

The eGFR decline depended on sex and age and changed only marginally after multivariable adjustment but decelerated with increasing age. Equations including cystatin C demonstrated a nonlinear slope challenging the previously assumed linearity of the decline of eGFR in old age.

CKD prevalence based on real-world data: continuous age-dependent lower reference limits of eGFR with CKD-EPI, FAS and EKFC algorithms

Purpose

Several recent articles discuss the need for a definition of chronic kidney disease (CKD) that embarks age-dependency and its impact on the prevalence of CKD. The relevance is derived from the common knowledge that renal function declines with age. The aim of this study was to calculate age-dependent eGFR lower reference limits and to consider their impact on the prevalence of CKD.

Methods

A real-world data set from patients with inconspicuous urinalysis was used to establish two quantile regression models which were used to calculate continuous age-dependent lower reference limits of CKD–EPI, FAS and EKFC–eGFR based on either single eGFR determinations or eGFR values that are stable over a period of at least 3 months (± 10% eGFR). The derived lower reference limits were used to calculate the prevalence of CKD in a validation data set. Prevalence calculation was done once without and once with application of the chronicity criterion.

Results

Both models yielded age-dependent lower reference limits of eGFR that are comparable to previously published data. The model using patients with stable eGFR resulted in higher eGFR reference limits. By applying the chronicity criterion, a lower prevalence of CKD was calculated when compared to one-time eGFR measurements (CKD–EPI: 9.8% vs. 8.3%, FAS: 8.0% vs. 7.2%, EKFC: 9.0% vs. 7.1%).

Conclusion

The application of age-dependent lower reference intervals of eGFR together with the chronicity criterion result in a lower prevalence of CKD which supports the estimates of recently published work and the idea of introducing age-dependency into the definition of CKD.

Chronic Kidney Disease Patients Visiting Various Hospital Departments: An Analysis in a Hospital in Central Tokyo, Japan

To further improve care for chronic kidney disease (CKD) patients, healthcare providers’ awareness of CKD must be raised. Proteinuria testing is essential for CKD care, and collaboration with specialists is recommended for advanced cases. We reviewed data from the electronic medical records of outpatients at our hospital to analyze the clinical departments visited by CKD patients, and the frequency of proteinuria testing and referrals to nephrologists. We defined CKD as an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² or a urine protein concentration (U-pro) ≥ +1. We found that 31.1% of the CKD tests in September 2021 were performed in clinical departments other than internal medicine. Furthermore, within 1 year, 68.0% of CKD patients identified in September 2020 underwent a urine dipstick test, and 33.7% underwent a quantitative test for urinary protein or albumin. Additionally, 27.5% of individuals with an eGFR < 30 mL/min/1.73 m² or U-pro ≥ +1 identified by non-nephrology departments in September 2020 visited the nephrology department within 1 year. Repeated assessments of these quality indicators may be useful for progress management in improving CKD care. Because CKD patients visited various departments in our hospital, campaigns to raise CKD awareness must reach a wide range of healthcare providers in hospitals.

A robust, accurate, sensitive LC-MS/MS method to measure indoxyl sulfate, validated for plasma and kidney cells

Proximal tubular damage is an important prognostic determinant in various chronic kidney diseases (CKDs). Currently available diagnostic methods do not allow for early disease detection and are neither efficient. Indoxyl sulfate (IS) is an endogenous metabolite and protein‐bound uremic toxin that is eliminated via renal secretion, but accumulates in plasma during tubular dysfunction. Therefore, it may be suitable as a tubular function marker. To evaluate this, a fast bioanalytical method was developed and validated for IS in various species and a kidney cell line using LC–MS/MS. An isotope‐labeled IS potassium salt as an internal standard and acetonitrile (ACN) as a protein precipitant were used for sample pretreatment. The analyte was separated on a Polaris 3 C18‐A column by gradient elution using 0.1% formic acid in water and ACN, and detected by negative electrospray ionization in selected reaction monitoring mode. The within‐day (≤ 4.0%) and between‐day (≤ 4.3%) precisions and accuracies (97.7 to 107.3%) were within the acceptable range. The analyte showed sufficient stability at all conditions investigated. Finally, applying this assay, significantly higher plasma and lower urine concentrations of IS were observed in mice with diabetic nephropathy with tubular damage, which encourages validation toward its use as a biomarker.

Gasotransmitters: Potential Therapeutic Molecules of Fibrotic Diseases

Fibrosis is defined as the pathological progress of excessive extracellular matrix (ECM), such as collagen, fibronectin, and elastin deposition, as the regenerative capacity of cells cannot satisfy the dynamic repair of chronic damage. The well-known features of tissue fibrosis are characterized as the presence of excessive activated and proliferated fibroblasts and the differentiation of fibroblasts into myofibroblasts, and epithelial cells undergo the epithelial-mesenchymal transition (EMT) to expand the number of fibroblasts and myofibroblasts thereby driving fibrogenesis. In terms of mechanism, during the process of fibrosis, the activations of the TGF-β signaling pathway, oxidative stress, cellular senescence, and inflammatory response play crucial roles in the activation and proliferation of fibroblasts to generate ECM. The deaths due to severe fibrosis account for almost half of the total deaths from various diseases, and few treatment strategies are available for the prevention of fibrosis as yet. Recently, numerous studies demonstrated that three well-defined bioactive gasotransmitters, including nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂S), generally exhibited anti-inflammatory, antioxidative, antiapoptotic, and antiproliferative properties. Besides these effects, a number of studies have reported that low-dose exogenous and endogenous gasotransmitters can delay and interfere with the occurrence and development of fibrotic diseases, including myocardial fibrosis, idiopathic pulmonary fibrosis, liver fibrosis, renal fibrosis, diabetic diaphragm fibrosis, and peritoneal fibrosis. Furthermore, in animal and clinical experiments, the inhalation of low-dose exogenous gas and intraperitoneal injection of gaseous donors, such as SNAP, CINOD, CORM, SAC, and NaHS, showed a significant therapeutic effect on the inhibition of fibrosis through modulating the TGF-β signaling pathway, attenuating oxidative stress and inflammatory response, and delaying the cellular senescence, while promoting the process of autophagy. In this review, we first demonstrate and summarize the therapeutic effects of gasotransmitters on diverse fibrotic diseases and highlight their molecular mechanisms in the process and development of fibrosis.

Prevalence, recognition and management of chronic kidney disease in Japan: population-based estimate using a healthcare database with routine health checkup data

BACKGROUND

We aimed to update information on the prevalence of chronic kidney disease (CKD) in Japan. We also explored whether CKD was properly recognized and managed.

METHODS

We used data from annual health checkups in 2017, compiling records for 5 million persons. These included laboratory results and were linked to healthcare utilization records via personal identifiers. CKD was defined as an estimated glomerular filtration rate <60 mL/min/1.73 m2. The prevalence was compared with that in 2005. Healthcare utilization, including laboratory tests, disease coding and medication for comorbid diabetes mellitus (DM) and hypertension (HT), was used as an indicator for the recognition and management of CKD.

RESULTS

Of the 761 565 records [median age 46 years (interquartile range 50-62)], CKD was found in 50 091 persons; the crude and age-adjusted prevalences were 63.1 and 71.8 per 1000 persons, respectively. CKD prevalence was significantly higher in 2017 than in 2005, with an increase of 14.1 per 1000 persons. Among persons with CKD, >95% sought medical services and 64.6% received laboratory tests within 180 days of the checkup. However, the diagnostic code suggestive of CKD was recorded in only 23.2% of patients and prescriptions for DM and HT were found in 31.2% (1590/5096) and 36.7% (8081/22 019) of comorbid persons, respectively.

CONCLUSIONS

The prevalence of CKD in Japan has increased over the past decade. However, recognition of CKD is likely suboptimal and there is room to improve the management of comorbid DM and HT.

Analysis of profibrogenic microRNAs (miRNAs) expression in urine and serum of chronic kidney disease (CKD) stage 1-4 patients and their relationship with proteinuria and kidney function

Purpose

Besides conventional kidney diseases diagnostics, micro RNAs (miRNAs) assessment in urine and serum is considered to be a promising non-invasive method of diagnostics of renal parenchymal diseases and valuable therapeutic target also. The purpose of the study was to investigate the role of several miRNAs as a markers of kidney damage.

Methods

Assessment of 45 chronic kidney disease (CKD) patients stage 1–4 and 17 healthy control. Sample of urine and blood was taken from each participant for molecular analysis using Real Time PCR method to identify such micro-RNAs as: hsa-miR-155-5p, hsa-miR-214-3p, hsa-miR-200a-5p, hsa-miR-29a-5p, hsa-miR-21-5p, hsa-miR-93-5p, and hsa-miR-196a-5p. Basic biochemical test was done. Analysis was performed in CKD patients group and subgroup with chronic glomerulonephritis (CGN) confirmed by kidney biopsy. Moreover, analysis was performed in subgroup with different estimated glomerular filtration rate (eGFR) (according to CKD–EPI equation: eGFR < 60 ml/min, eGFR > 60 ml/min) and different daily protein excretion (DPE): (DPE < 3.5 g; DPE > 3.5 g).

Results

Increased relative expression of hsa-miR-29-5p, hsa-miR-21-5p, and hsa-miR-196a-5p and decreased expression of hsa-miR-155-5p, hsa-miR-214-5p, hsa-miR-200a-5p, and hsa-miR-93-5p was demonstrated in urine of analyzed CKD patients. In subpopulation of chronic glomerulonephritis (CGN) patients, there was higher level of expression in urine of hsa-miR-155-5p, hsa-miR 214-3p, hsa-miR-93-5p, and hsa-miR-196a-5p in CGN with DPE < 3.5 g. CGN patients with eGFR < 60 ml/min showed higher expression level of miRNAs such as hsa-miR-214-3p, hsa-miR-29-5p, hsa-miR-93-5p, and hsa-miR-196-5p in urine. There was increase in hsa-miR 155-5p, hsa-miR-214-3p, and hsa-miR-200a-5p serum expression level in CKD population and reduction of hsa-miR-29a-5p, hsa-miR-21-5p, and hsa-miR-93-5p expression. Increased level of expression of hsa-miR-155-5p; hsa-miR-214-3p, hsa-miR-200a-5p, and hsa-miR-29-5p was found in CGN patients with eGFR > 60 ml/min.

Conclusion

Increased relative expression of profibrogenic miRNAs in urine or serum of CKD patients with eGFR > 60 ml/min and DPE < 3.5 g may indicate higher degree of fibrosis at early CKD stages.

Local cyclic adenosine monophosphate signalling cascades-Roles and targets in chronic kidney disease

The molecular mechanisms underlying chronic kidney disease (CKD) are poorly understood and treatment options are limited, a situation underpinning the need for elucidating the causative molecular mechanisms and for identifying innovative treatment options. It is emerging that cyclic 3',5'-adenosine monophosphate (cAMP) signalling occurs in defined cellular compartments within nanometre dimensions in processes whose dysregulation is associated with CKD. cAMP compartmentalization is tightly controlled by a specific set of proteins, including A-kinase anchoring proteins (AKAPs) and phosphodiesterases (PDEs). AKAPs such as AKAP18, AKAP220, AKAP-Lbc and STUB1, and PDE4 coordinate arginine-vasopressin (AVP)-induced water reabsorption by collecting duct principal cells. However, hyperactivation of the AVP system is associated with kidney damage and CKD. Podocyte injury involves aberrant AKAP signalling. cAMP signalling in immune cells can be local and slow the progression of inflammatory processes typical for CKD. A major risk factor of CKD is hypertension. cAMP directs the release of the blood pressure regulator, renin, from juxtaglomerular cells, and plays a role in Na⁺ reabsorption through ENaC, NKCC2 and NCC in the kidney. Mutations in the cAMP hydrolysing PDE3A that cause lowering of cAMP lead to hypertension. Another major risk factor of CKD is diabetes mellitus. AKAP18 and AKAP150 and several PDEs are involved in insulin release. Despite the increasing amount of data, an understanding of functions of compartmentalized cAMP signalling with relevance for CKD is fragmentary. Uncovering functions will improve the understanding of physiological processes and identification of disease-relevant aberrations may guide towards new therapeutic concepts for the treatment of CKD.

Kidney Disease in Diabetic Patients: From Pathophysiology to Pharmacological Aspects with a Focus on Therapeutic Inertia

Diabetes mellitus represents a growing concern, both for public economy and global health. In fact, it can lead to insidious macrovascular and microvascular complications, impacting negatively on patients' quality of life. Diabetic patients often present diabetic kidney disease (DKD), a burdensome complication that can be silent for years. The average time of onset of kidney impairment in diabetic patients is about 7-10 years. The clinical impact of DKD is dangerous not only for the risk of progression to end-stage renal disease and therefore to renal replacement therapies, but also because of the associated increase in cardiovascular events. An early recognition of risk factors for DKD progression can be decisive in decreasing morbidity and mortality. DKD presents patient-related, clinician-related, and system-related issues. All these problems are translated into therapeutic inertia, which is defined as the failure to initiate or intensify therapy on time according to evidence-based clinical guidelines. Therapeutic inertia can be resolved by a multidisciplinary pool of healthcare experts. The timing of intensification of treatment, the transition to the best therapy, and dietetic strategies must be provided by a multidisciplinary team, driving the patients to the glycemic target and delaying or overcoming DKD-related complications. A timely nephrological evaluation can also guarantee adequate information to choose the right renal replacement therapy at the right time in case of renal impairment progression.

Estimating the prevalence of definitive chronic kidney disease in the Japanese general population

BACKGROUND

Most data on chronic kidney disease (CKD) prevalence has been based on single measurements of renal function and proteinuria. The aim was to determine the prevalence of CKD diagnosed by chronic proteinuria and/or reduced eGFR in a recent year in Japan.

METHODS

In the main study, using a population-based cohort in Japan, the overall prevalence of CKD, defined as persistent positive proteinuria and/or eGFR < 60 ml/min/1.73 m², was determined. Of 2,849,557 persons, 763,104 had data for eGFR and proteinuria in both 2014 and 2015. For estimating number of CKD cases in Japanese adults, a regional cohort data with age ranging 22-87 years (N = 22,037) was further applied to the analysis.

RESULTS

Definitive CKD was present in 2.3-23.0% of men and 1.7-17.1% of women age from 40 to 74 years in the main cohort. The estimated prevalence of reduced eGFR and/or proteinuria in the baseline year alone was 15.7% in men and 13.6% in women; the prevalence of definitive CKD was 10.9% in men and 9.2% in women. The number of CKD cases based on a single-year test in Japanese adults over 20 years of age increased from 13.3 million to 14.8 million between 2005 and 2015.

CONCLUSIONS

Recent changes in prevalence of CKD seem to be mainly caused by an increase in Japan's elderly population. Although past reports may lead to overdiagnosis of CKD by a single-year test, the estimated number of definitive CKD was 10.2 million in 2015.

Identification of Patients with CKD in Medical Databases: A Comparison of Different Algorithms

BACKGROUND AND OBJECTIVES

Despite CKD consensus definitions, epidemiologic studies use multiple different algorithms to identify CKD. We aimed to elucidate if this affects the patient characteristics and the estimated prevalence and prognosis of CKD by applying six different algorithms to identify CKD in population-based medical databases and compare the cohorts.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients with CKD in Northern Denmark (2009-2016) were identified using six different algorithms: five were laboratory based defined by (1) one measured outpatient eGFR <60 ml/min per 1.73 m2 (single test, n=103,435), (2) two such findings ≥90 days apart (Kidney Disease Improving Global Outcomes, n=84,688), (3) two such findings ≥90 days apart with no eGFR >60 ml/min per 1.73 m2 observed in-between (Kidney Disease Improving Global Outcomes, persistent, n=68,994), (4) two such findings ≥90 and <365 days apart (Kidney Disease Improving Global Outcomes, time limited, n=75,031), and (5) two eGFRs <60 ml/min per 1.73 m2 or two urine albumin-creatinine ratios >30 mg/g ≥90 days apart (Kidney Disease Improving Global Outcomes, eGFR/albuminuria, n=100,957). The sixth included patients identified by reported in- and outpatient hospital International Classification of Diseases diagnoses of CKD (hospital-diagnosed, n=27,947). For each cohort, we estimated baseline eGFR, CKD prevalence, and 1-year mortality using the Kaplan-Meier method.

RESULTS

The five different laboratory-based algorithms resulted in large differences in the estimated prevalence of CKD from 4637-8327 per 100,000 population. In contrast, 1-year mortality varied only slightly (7%-9%). Baseline eGFR levels at diagnosis were comparable (53-56 ml/min per 1.73 m2), whereas median time since first recorded eGFR <60 ml/min per 1.73 m2 varied from 0 months (single-test) to 17 months (Kidney Disease Improving Global Outcomes, persistent). The hospital-diagnosed algorithm yielded markedly lower CKD prevalence (775 per 100,000 population), a lower baseline eGFR (47 ml/min per 1.73 m2), longer time since first eGFR <60 ml/min per 1.73 m2 (median 70 months), and much higher 1-year mortality (22%).

CONCLUSIONS

Population prevalence of CKD identified in medical databases greatly depends on the applied algorithm to define CKD. Despite these differences, laboratory-based algorithms produce cohorts with similar prognosis.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2021_03_11_CJN15691020_final.mp3.

Effects of Artemisia supplementation on anorexia in hemodialysis patients: a randomized, double-blind placebo-controlled trial

OBJECTIVES

One of the most important problems of hemodialysis (HD) patients is anorexia due to the lack of proper treatment for it and on the other hand kidney disease is increasing. We designed a randomized controlled clinical trial to investigate the effects of Artemisia supplementation on anorexia in HD patients.

MATERIALS AND METHODS

This randomized, double-blind, placebo-controlled trial was carried out on 58 subjects with HD, aged 55-65 years old. Participants were randomly divided into two groups. One group received 250 mg/day of Artemisia supplement capsule for six weeks (n=26), and the other group was given placebo for the same time duration and dosage (n=32). The serum concentrations of urea, creatinine, albumin and hemoglobin were measured enzymatically using commercial kits. Anorexia score was measured using a Simplified Nutritional Appetite Questionnaire (SNAQ). Independent t-test analysis were applied to evaluate the data.

RESULTS

The results showed that the Artemisia supplementation significantly improved the anorexia in HD patients, for six weeks (p<0.05). However, it did not significantly effect on the albumin, hemoglobin, urea, creatinine, arm circumference, and body mass index (p>0.05).

CONCLUSION

According to the outcomes of this study, Artemisia supplementation can be effective as an adjunct therapy for improve anorexia in HD patients.

Podocyte Injury Through Interaction Between Tlr8 and Its Endogenous Ligand miR-21 in Obstructed and Its Collateral Kidney

While chronic kidney disease is prevalent in adults, obstructive nephropathy (ON) has been reported in both young and old patients. In ON, tubulointerstitial lesions (TILs) have been widely investigated, but glomerular lesions (GLs) have been largely neglected. Here, we show a novel mechanism underlying GL development in ON in young and old mice. TILs develop earlier than GLs owing to infiltration of inflammatory cells in the tubulointerstitium, but GLs develop following the activation of Toll-like receptor 8 (Tlr8) even though the absence of inflammatory cells infiltrating the glomerulus. TLR8 and interleukin 1 beta (IL1β) proteins colocalize with reducing podocyte function markers (PFMs), indicating the activation of TLR8 signaling in injured podocytes. Furthermore, glomerular and serum levels of miR-21, an endogenous ligand for Tlr8, were higher in the ON mouse model than in the sham control. The glomerular expression of Tlr8 positively correlates with miR-21 and the downstream cytokines Il1b and Il6 and negatively correlated with PFMs (Nphs1 and Synpo). We also show the colocalization of TLR8 and IL1β proteins with reducing PFMs in both obstructed and collateral kidney of young and old mice. Furthermore, in vitro study results revealed higher expression of Tlr8 and its downstream cytokines in glomeruli from obstructed kidneys following treatment with miR-21 mimic than in the control. In conclusion, the overexpression of Tlr8 may serve as a plausible mechanism underlying GL development in ON through podocyte injury.

Vasculature-Associated Lymphoid Tissue: A Unique Tertiary Lymphoid Tissue Correlates With Renal Lesions in Lupus Nephritis Mouse Model

Lupus nephritis (LN) is a common complication in young patients and the most predominant cause of glomerulonephritis. Infiltrating immune cells and presence of immunocomplexes in the kidney are hallmarks of LN, which is closely associated with renal lesions (RLs). However, their regulatory mechanism in the kidney remains unclear, which is valuable for prevention of RL development. Here, we show the development of vasculature-associated lymphoid tissue (VALT) in LN, which is related to renal inflammatory cytokines, indicating that VALT is a unique tertiary lymphoid tissue. Transcriptomic analysis revealed different chemokines and costimulatory molecules for VALT induction and organization. Vascular and perivascular structures showed lymphoid tissue organization through lymphorganogenic chemokine production. Transcriptional profile and intracellular interaction also demonstrated antigen presentation, lymphocyte activity, clonal expansion, follicular, and germinal center activity in VALT. Importantly, VALT size was correlated with infiltrating immune cells in kidney and RLs, indicating its direct correlation with the development of RLs. In addition, dexamethasone administration reduced VALT size. Therefore, inhibition of VALT formation would be a novel therapeutic strategy against LN.

Effects of sleep apnea and kidney dysfunction on objective sleep quality in nondialyzed patients with chronic kidney disease: an ESADA study

STUDY OBJECTIVES

Patients with chronic kidney disease (CKD) often report poor sleep quality, but they commonly exhibit OSA. The aim of this study was to evaluate the influence of OSA severity and of estimated glomerular filtration rate impairment on objective sleep quality in nondialyzed patients with CKD, defined as an estimated glomerular filtration rate <60 mL/min/1.73m².

METHODS

Polysomnographic sleep characteristics were compared between patients with (n = 430) and without CKD (n = 6,639) in the European Sleep Apnea Database cohort. Comparisons were repeated in 375 patients with CKD and 375 control patients without CKD matched for sleep center, age, sex, and AHI, and in 310 matched CKD and non-CKD patients without psychiatric disturbances.

RESULTS

Among all patients with and without CKD, total sleep time was similar but sleep stage N1 (median 8.7% [IQR 4.8-18.0] vs 6.7% [3.6-12.7], respectively) and sleep stage R (12.6% [6.8-17.7] vs 14.2% [8.8-19.8], respectively) significantly differed (P < .0001). No difference in sleep characteristics was observed between matched patients either with or without psychiatric disturbances. After subdividing the matched patients according to AHI tertile (<25, ≥25 to <49, and ≥49 events/h) and estimated glomerular filtration rate (≥60, 45 to <60, <45 mL/min/1.73m²), we found a significant effect of AHI on sleep stages N2, N3, and R (P < .001), but there was no effect of CKD.

CONCLUSIONS

In nondialyzed patients with CKD, objective sleep quality is influenced similarly by AHI as in patients without CKD but is not affected by CKD severity. Previously reported poor sleep quality in CKD may partly result from the high prevalence of OSA in CKD.

Optimized Identification of Advanced Chronic Kidney Disease and Absence of Kidney Disease by Combining Different Electronic Health Data Resources and by Applying Machine Learning Strategies

Automated identification of advanced chronic kidney disease (CKD ≥ III) and of no known kidney disease (NKD) can support both clinicians and researchers. We hypothesized that identification of CKD and NKD can be improved, by combining information from different electronic health record (EHR) resources, comprising laboratory values, discharge summaries and ICD-10 billing codes, compared to using each component alone. We included EHRs from 785 elderly multimorbid patients, hospitalized between 2010 and 2015, that were divided into a training and a test (n = 156) dataset. We used both the area under the receiver operating characteristic (AUROC) and under the precision-recall curve (AUCPR) with a 95% confidence interval for evaluation of different classification models. In the test dataset, the combination of EHR components as a simple classifier identified CKD ≥ III (AUROC 0.96[0.93-0.98]) and NKD (AUROC 0.94[0.91-0.97]) better than laboratory values (AUROC CKD 0.85[0.79-0.90], NKD 0.91[0.87-0.94]), discharge summaries (AUROC CKD 0.87[0.82-0.92], NKD 0.84[0.79-0.89]) or ICD-10 billing codes (AUROC CKD 0.85[0.80-0.91], NKD 0.77[0.72-0.83]) alone. Logistic regression and machine learning models improved recognition of CKD ≥ III compared to the simple classifier if only laboratory values were used (AUROC 0.96[0.92-0.99] vs. 0.86[0.81-0.91], p < 0.05) and improved recognition of NKD if information from previous hospital stays was used (AUROC 0.99[0.98-1.00] vs. 0.95[0.92-0.97]], p < 0.05). Depending on the availability of data, correct automated identification of CKD ≥ III and NKD from EHRs can be improved by generating classification models based on the combination of different EHR components.

RENA Study: Cross-Sectional Study to Evaluate CKD Prevalence in Portugal

INTRODUCTION

Chronic kidney disease (CKD) is a major global public health problem associated with increased risk of cardiovascular morbidity, premature mortality, and decreased quality of life. In Portugal, the PREVADIAB study showed a prevalence of CKD stages 3-5 of 6.1%. To overcome the limitations of the PREVADIAB study, the RENA study aimed to provide an estimate of the prevalence of CKD at a national level and to characterize CKD patients.

METHODS

This was a cross-sectional study including users of Primary Health Care Units aged 18 or more. After obtaining written informed consent, sociodemographic and clinical data were recorded through a structured questionnaire, anthropometric measurements were taken, and blood and urine samples were collected. All participants initially meeting the criteria for CKD were contacted at least 3 months after the initial assessment for confirmation of the analytical results.

RESULTS

A total of 3,135 individuals were included, 65.4% were female, and the mean age was 56.7 ± 15.9 years. The prevalence of hypertension, dyslipidemia, and diabetes was 38, 32, and 16%, respectively, and 31% were obese. After data adjustment by gender, age group, and geographical region, the global prevalence of CKD was 20.9% (95% CI: 6.5-35.3%), with no differences between genders and a significant increase with the advance of the age groups.

CONCLUSION

Our study showed a CKD prevalence above the worldwide and Europe average. Despite the study limitations, it has become clear that it is urgent to identify CKD patients earlier and to develop awareness and educational programs to prevent CKD and its associated diseases.

The prevalence of chronic kidney disease in Iceland according to KDIGO criteria and age-adapted estimated glomerular filtration rate thresholds

Most epidemiological studies on chronic kidney disease (CKD) are based solely on estimated glomerular filtration rate (eGFR). Few studies have included proteinuria, while the chronicity criterion is usually omitted. To explore this, we examined the prevalence of CKD stages 1-5 in Iceland based on multiple markers of kidney damage. All serum creatinine values, urine protein measurements and diagnostic codes for kidney diseases and comorbid conditions for people aged 18 years and older were obtained from electronic medical records of all healthcare institutions in Iceland in 2008-2016. CKD was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guideline using diagnoses indicative of a chronic kidney disease, proteinuria and/or an eGFR under 60 mL/min/1.73 m² for over three months. Mean annual age-standardized prevalence of CKD stages 1-5 was calculated based on the KDIGO criteria and age-adapted eGFR thresholds from 2,120,147 creatinine values for 218,437 individuals, 306,531 proteinuria measurements for 86,364 individuals and 6973 individuals carrying a kidney disease diagnosis. Median age was 63 years (range, 18-106) and 47% were male. The mean annual age standardized CKD prevalence was 5.13% for men and 6.75% for women using the KDIGO criteria but by age-adapted eGFR cut-offs, the prevalence was 3.27% for men and 4.01% for women. Thus, our nationwide study, defining CKD in Iceland with strict adherence to the KDIGO criteria, demonstrates a lower prevalence of CKD than anticipated from most previous studies.

Longitudinal Changes in Kidney Function Estimated from Cystatin C and Its Association with Mortality in Elderly Women

BACKGROUND/AIMS

Prospective data on age-related changes in kidney function are required, especially since the current Kidney Disease Improving Global Outcomes (KDIGO) definition has been suggested to classify a large number of elderly people with CKD.

OBJECTIVE

This study, a complement to our previous Cr-based study in the same cohort, is aimed at evaluating cystatin C (cysC)-based changes in kidney function during aging in older women and analyzing the association between CKD and mortality through 10 years of follow-up.

METHODS

cysC was available in 981 women from the Osteoporosis Prospective Risk Assessment (OPRA) cohort, all aged 75 years on entry. Reinvestigations were made after 5 (n = 685) and 10 years (n = 365). Kidney function was estimated (estimated glomerular filtration rate [eGFR]) using Chronic Kidney Disease Epidemiology Collaboration cysC and Caucasian, Asian, Pediatric, and Adult cysC equations and the change in function calculated. Women were staged equivalent to CKD stage 1, 2, 3a, or 3b-5 according to the KDIGO classification. Mortality risk was estimated for 5-year or 10-year follow-up time using Cox proportional hazard analyses (reference category, CKD stages 1 and 2).

RESULTS

Mortality risk for women with the worst kidney function (CKD stages 3b-5) increased during both 5-year follow-up times compared to that for women in stages 1 and 2 (age 75-80 years: adjusted Hazard Ratio [HRadj] 3.9, 95% confidence interval [CI] 2.3-6.5; age 80-85 years: HRadj 1.7, 95% CI 1.0-2.7). In contrast, women in stage 3a had increased risk only in the first 5-year follow-up (HRadj 1.7, 95% CI 1.0-3.0, age 75-80 years). Change in kidney function amounted to a loss of 1.9 (±1.4) mL/min/1.73 m2 per year during the 10-year follow-up, and at age 85 years, 4 of every 5 women had an eGFR equivalent to CKD.

CONCLUSION

In the future, an age-adapted definition of CKD, lowering the threshold for CKD in the elderly, may be beneficial to avoid overdiagnosis of CKD.

Theory-Based Interventions to Promote Fluid Intake Adherence Among Dialysis Patients: A Systematic Review

BACKGROUND AND PURPOSE

Dialysis involves a complex regimen including diet, fluid, medication, and treatment. Therapeutic regimen adherence determines the therapeutic success, quality of life, and survival of patients on dialysis. Complying with fluid management is the most difficult among the therapeutic regimen. Several theory-based interventions have been designed to promote fluid intake compliance in patients receiving dialysis. This review has two aims. One is to explore the effectiveness of theory-based interventions. The other is to examine the extent of the combination of theory and interventions in improving adherence to fluid intake among dialysis patients.

METHODS

A literature review was performed using PubMed, PsycINFO, Embase, Web of Science, and the Cochrane Library to acquire associated studies. Data were extracted independently by two researchers. The degree of theory application was accessed using a theory coding scheme (TCS).

RESULTS

Eight studies were identified as eligible for inclusion, and five theories were cited as basis (health belief model, social cognitive theory, self-regulation model, transtheoretical model). According to the TCS, adherence outcomes and the extent of theory use were not optimal.

IMPLICATIONS FOR PRACTICE

Combining theory with patient health education might be beneficial in improving fluid intake adherence of dialysis patients. The framework and TCS could be considered to guide theory utilization and promote nursing education in improving the quality of renal nursing care.

Prevalence of chronic kidney disease in the community using data from OxRen: a UK population-based cohort study

Background

Chronic kidney disease (CKD) is a largely asymptomatic condition of diminished renal function, which may not be detected until advanced stages without screening.

Aim

To establish undiagnosed and overall CKD prevalence using a cross-sectional analysis.

Design and setting

Longitudinal cohort study in UK primary care.

Method

Participants aged ≥60 years were invited to attend CKD screening visits to determine whether they had reduced renal function (estimated glomerular filtration rate [eGFR] <60 ml/min/1.73 m² or albumin:creatinine ratio ≥3 mg/mmol). Those with existing CKD, low eGFR, evidence of albuminuria, or two positive screening tests attended a baseline assessment (CKD cohort).

Results

A total of 3207 participants were recruited and 861 attended the baseline assessment. The CKD cohort consisted of 327 people with existing CKD, 257 people with CKD diagnosed through screening (CKD prevalence of 18.2%, 95% confidence interval [CI] = 16.9 to 19.6), and 277 with borderline/transient decreased renal function. In the CKD cohort, 54.4% were female, mean standard deviation (SD) age was 74.0 (SD 6.9) years, and mean eGFR was 58.0 (SD 18.4) ml/min/1.73 m². Of the 584 with confirmed CKD, 44.0% were diagnosed through screening. Over half of the CKD cohort (51.9%, 447/861) fell into CKD stages 3–5 at their baseline assessment, giving an overall prevalence of CKD stages 3–5 of 13.9% (95% CI = 12.8 to 15.1). More people had reduced eGFR using the Modification of Diet in Renal Disease (MDRD) equation than with CKD Epidemiology Collaboration (CKD-EPI) equation in the 60–75-year age group and more had reduced eGFR using CKD-EPI in the ≥80-year age group.

Conclusion

This study found that around 44.0% of people living with CKD are undiagnosed without screening, and prevalence of CKD stages 1–5 was 18.2% in participants aged >60 years. Follow-up will provide data on annual incidence, rate of CKD progression, determinants of rapid progression, and predictors of cardiovascular events.

Global, regional, and national burden of chronic kidney disease, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017

BACKGROUND

Health system planning requires careful assessment of chronic kidney disease (CKD) epidemiology, but data for morbidity and mortality of this disease are scarce or non-existent in many countries. We estimated the global, regional, and national burden of CKD, as well as the burden of cardiovascular disease and gout attributable to impaired kidney function, for the Global Burden of Diseases, Injuries, and Risk Factors Study 2017. We use the term CKD to refer to the morbidity and mortality that can be directly attributed to all stages of CKD, and we use the term impaired kidney function to refer to the additional risk of CKD from cardiovascular disease and gout.

METHODS

The main data sources we used were published literature, vital registration systems, end-stage kidney disease registries, and household surveys. Estimates of CKD burden were produced using a Cause of Death Ensemble model and a Bayesian meta-regression analytical tool, and included incidence, prevalence, years lived with disability, mortality, years of life lost, and disability-adjusted life-years (DALYs). A comparative risk assessment approach was used to estimate the proportion of cardiovascular diseases and gout burden attributable to impaired kidney function.

FINDINGS

Globally, in 2017, 1·2 million (95% uncertainty interval [UI] 1·2 to 1·3) people died from CKD. The global all-age mortality rate from CKD increased 41·5% (95% UI 35·2 to 46·5) between 1990 and 2017, although there was no significant change in the age-standardised mortality rate (2·8%, -1·5 to 6·3). In 2017, 697·5 million (95% UI 649·2 to 752·0) cases of all-stage CKD were recorded, for a global prevalence of 9·1% (8·5 to 9·8). The global all-age prevalence of CKD increased 29·3% (95% UI 26·4 to 32·6) since 1990, whereas the age-standardised prevalence remained stable (1·2%, -1·1 to 3·5). CKD resulted in 35·8 million (95% UI 33·7 to 38·0) DALYs in 2017, with diabetic nephropathy accounting for almost a third of DALYs. Most of the burden of CKD was concentrated in the three lowest quintiles of Socio-demographic Index (SDI). In several regions, particularly Oceania, sub-Saharan Africa, and Latin America, the burden of CKD was much higher than expected for the level of development, whereas the disease burden in western, eastern, and central sub-Saharan Africa, east Asia, south Asia, central and eastern Europe, Australasia, and western Europe was lower than expected. 1·4 million (95% UI 1·2 to 1·6) cardiovascular disease-related deaths and 25·3 million (22·2 to 28·9) cardiovascular disease DALYs were attributable to impaired kidney function.

INTERPRETATION

Kidney disease has a major effect on global health, both as a direct cause of global morbidity and mortality and as an important risk factor for cardiovascular disease. CKD is largely preventable and treatable and deserves greater attention in global health policy decision making, particularly in locations with low and middle SDI.

FUNDING

Bill & Melinda Gates Foundation.

Comparison of the Effect of Multimedia and Booklet Methods on Quality of Life of Kidney Transplant Patients: A Randomized Clinical Trial Study

Background:

Proper education can improve the quality of life. Multimedia as an interactive educational method and booklet as a traditional one have their own unique effects. This study aimed at compare the interactive multimedia and booklet methods at the time of discharge on the quality of life of kidney transplant patients

Methods:

In this single-blind interventional study, 80 patients from Bouali Hospital, Shiraz, from September 2017 until June 2018 were selected by convenience sampling, and then divided into two groups (booklet and interactive multimedia) by block randomization. Intervention for the first group included short and long-term care information in the form of a booklet, and an interactive multimedia CD with the same content for the second group. Quality of life was assessed by kidney transplant questionnaire (KTQ) at the time of discharge and after two months. Adherence to education was verified by phone. The data were analyzed through SPSS v.24 software using independent and paired t-tests. Plt;0.05 was considered significant

Results:

The mean overall quality of life score in both groups increased significantly, P=0.044 for the booklet group and P=0.039 for the multimedia group. In emotional, fatigue, uncertainty/fear domains, both groups showed improvement after the intervention (P&lt;0.05). However, in physical symptoms and appearance domains, differences were not significant, before and after education. After intervention, no significant difference was observed between the two groups in the overall and specific domains of quality of life score (P=0.437)

Conclusion:

Both methods had positive impacts on the quality of life and emotional, fatigue and uncertainty/fear domains.

Trial Registration Number: IRCT201608272950N1

Too much nephrology? The CKD epidemic is real and concerning. A CON view

The prevalence of chronic kidney disease (CKD) clearly depends on its definition, and the definition used most often is the one proposed by the Kidney Disease: Improving Global Outcomes guidelines in 2012: 'CKD is defined as abnormalities of kidney structure or function, present for >3 months, with implications for health.' Abnormality of kidney function is a glomerular filtration rate (GFR) <60 mL/min/1.73 m2, and the most frequently used marker of kidney damage is the presence of albuminuria [albumin excretion rate >30 mg/24 h or albumin/creatinine ratio (ACR) >30 mg/g (or 3 mg/mmol)]. However, two major aspects of this definition could explain why CKD prevalence is, in our view, overstated in most epidemiological studies. First, the fixed threshold at 60 mL/min/1.73 m2 is questionable because normal GFR decreases with age. This and the profound consequence it has on CKD epidemiology will be illustrated. The second aspect of the definition is the criterion of chronicity, which is ignored by the vast majority of epidemiological studies. In other words, confirming CKD (low GFR and/or high ACR) is mandatory. Indeed, a large proportion of subjects with a low first GFR level has a normal GFR level when tested a second time. The prevalence of CKD may hence, in fact, be considerably lower although still neither negligible nor irrelevant.

Cause-specific mortality in the general population with transient dipstick-proteinuria

Recently, changes in urinary albumin and in GFR have been recognized as risk factors for the development of end-stage kidney disease and mortality. Though most clinical epidemiology studies of chronic kidney disease (CKD) used renal function and proteinuria at baseline alone, definitive diagnosis of CKD with multiple measurements intensifies the differences in the risk for mortality between the CKD and non-CKD populations. We hypothesized that a transient diagnosis of proteinuria and reduced renal function each indicate a significantly higher mortality compared to definitive non-CKD as the negative control and lower mortality compared with definitive CKD as the positive control. The present longitudinal study evaluated a general-population cohort of 338,094 persons who received annual health checkups, with a median 4.3-year study period. There were 2,481 deaths, including 510 CVD deaths (20.6%) and 1,328 cancer deaths (53.5%), and mortality risk was evaluated for transient proteinuria and for transiently reduced renal function. The hazard ratios (HRs) for all-cause mortality and cancer mortality were not significant, but that for cardiovascular mortality was significantly higher for transient proteinuria (HR, 1.94 [95% confidence interval, 1.27–2.96] in men and 2.78 [1.50–5.16] in women). On the other hand, transiently reduced renal function was not significant for either cardiovascular mortality risk or cancer mortality risk. We surmise that this is the first study of the mortality risk of transient dipstick proteinuria in a large general-population cohort with cause-specific death registration. Transiently positive proteinuria appears to be a significant risk specifically for cardiovascular mortality compared with definitely negative for proteinuria.

[Concordance between the equations "Chronic Kidney Disease Epidemiological Collaboration" and "Modification of Diet in Renal Disease" with the "Berlin Initiative Study" to estimate renal function in the elderly]

OBJECTIVE

Estimated glomerular filtration rate (eGFR) is calculated routinely using creatinine-based formulas, but their reliability in the elderly is limited. The aim of this study was to analyse the concordance between the BIS1 equation which is specific for the elderly, and the usual CKD-EPI and MDRD-IDMS in a large population over 70 years of age.

MATERIAL AND METHODS

Retrospective cross-sectional study in which the eGFR was calculated using BIS1, CKD-EPI and MDRD-IDMS equations based on gender, age, and creatinine data of 85,089 subjects (58.5% women, mean age 78 years [IQR 73-83]).The following statistics were carried out: Wilcoxon test, Bland-Altman graphic analysis, study of the concordance using the intraclass correlation coefficient (ICC), and comparison tables for the classification of CKD.

RESULTS

The median of the eGFRs using BIS1 was 58mL/min/1.73m² (IQR 48-70), using CKD-EPI was 68mL/min/1.73m² (IQR 53-84), and using MDRD it was 68mL/min/1.73m² (IQR 53-82). The concordance between BIS1 and CKD-EPI (intraclass correlation coefficient =0.87) was found to be acceptable. It was lower with MDRD (intraclass correlation coefficient =0.81). A mean difference of 8mL/min/1.73m² (SD 2.6-18) was found BIS1 vs. CKD-EPI, and 10mL/min/1.73m² (SD 6-27) with BIS1 vs. MDRD, which was maintained when stratifying by gender and age groups.

CONCLUSIONS

Despite the acceptable statistical agreement, the eGFR obtained with the BIS1 equation is not interchangeable with CKD-EPI or with MDRD-IDMS. The BIS1 equation gives lower values than CKD-EPI, and classifies patients into a higher level of CKD, mainly when the eGFR is above 30mL/min/1.73 m².

A simple method for the isolation and detailed characterization of primary human proximal tubule cells for renal replacement therapy

The main physiological functions of renal proximal tubule cells in vivo are reabsorption of essential nutrients from the glomerular filtrate and secretion of waste products and xenobiotics into urine. Currently, there are several established cell lines of human origin available as in vitro models of proximal tubule. However, these cells appeared to be limited in their biological relevance, because essential characteristics of the original tissue are lost once the cells are cultured. As a consequence of these limitations, primary human proximal tubule cells constitute a suitable and a biologically more relevant in vitro model to study this specific segment of the nephron and therefore, these cells can play an important role in renal regenerative medicine applications. Here, we describe a protocol to isolate proximal tubule cells from human nephrectomies. We explain the steps performed for an in-depth characterization of the cells, including the study of markers from others segments of the nephron, with the goal to determine the purity of the culture and the stability of proteins, enzymes, and transporters along time. The human proximal tubule cells isolated and used throughout this study showed many proximal tubule characteristics, including monolayer organization, cell polarization with the expression of tight junctions and primary cilia, expression of proximal tubule–specific proteins, such as megalin and sodium/glucose cotransporter 2, among others. The cells also expressed enzymatic activity for dipeptidyl peptidase IV, as well as for gamma glutamyl transferase 1, and expressed transporter activity for organic anion transporter 1, P-glycoprotein, multidrug resistance proteins, and breast cancer resistance protein. In conclusion, characterization of our cells confirmed presence of putative proximal tubule markers and the functional expression of multiple endogenous organic ion transporters mimicking renal reabsorption and excretion. These findings can constitute a valuable tool in the development of bioartificial kidney devices.

Gut Dysbiosis and the Intestinal Microbiome: Streptococcus thermophilus a Key Probiotic for Reducing Uremia

In the intestines, probiotics can produce antagonistic effects such as antibiotic–like compounds, bactericidal proteins such as bacteriocins, and encourage the production of metabolic end products that may assist in preventing infections from various pathobionts (capable of pathogenic activity) microbes. Metabolites produced by intestinal bacteria and the adoptions of molecular methods to cross-examine and describe the human microbiome have refreshed interest in the discipline of nephology. As such, the adjunctive administration of probiotics for the treatment of chronic kidney disease (CKD) posits that certain probiotic bacteria can reduce the intestinal burden of uremic toxins. Uremic toxins eventuate from the over manifestation of glucotoxicity and lipotoxicity, increased activity of the hexosamine and polyol biochemical and synthetic pathways. The accumulation of advanced glycation end products that have been regularly associated with a dysbiotic colonic microbiome drives the overproduction of uremic toxins in the colon and the consequent local pro-inflammatory processes. Intestinal dysbiosis associated with significant shifts in abundance and diversity of intestinal bacteria with a resultant and maintained uremia promoting an uncontrolled mucosal pro-inflammatory state. In this narrative review we further address the efficacy of probiotics and highlighted in part the probiotic bacterium Streptococcus thermophilus as an important modulator of uremic toxins in the gut of patients diagnosed with chronic kidney disease. In conjunction with prudent nutritional practices it may be possible to prevent the progression of CKD and significantly downregulate mucosal pro-inflammatory activity with the administration of probiotics that contain S. thermophilus.

Matrine suppresses lipopolysaccharide-induced fibrosis in human peritoneal mesothelial cells by inhibiting the epithelial-mesenchymal transition

Background:

Peritoneal fibrosis is the primary reason that patients with end-stage renal disease (ESRD) have to cease peritoneal dialysis. Peritonitis caused by Gram-negative bacteria such as Escherichia coli (E. coli) were on the rise. We had previously shown that matrine inhibited the formation of biofilm by E. coli. However, the role of matrine on the epithelial-mesenchymal transition (EMT) in peritoneal mesothelial cells under chronic inflammatory conditions is still unknown.

Methods:

We cultured human peritoneal mesothelial cells (HPMCs) with lipopolysaccharide (LPS) to induce an environment that mimicked peritonitis and investigated whether matrine could inhibit LPS-induced EMT in these cells. In addition, we investigated the change in expression levels of the miR-29b and miR-129-5p.

Results:

We found that 10 μg/ml of LPS induced EMT in HPMCs. Matrine inhibited LPS-induced EMT in HPMCs in a dose-dependent manner. We observed that treatment with matrine increased the expression of E-cadherin (F = 50.993, P < 0.01), and decreased the expression of alpha-smooth muscle actin (F = 32.913, P < 0.01). Furthermore, we found that LPS reduced the expression levels of miR-29b and miR-129-5P in HPMCs, while matrine promoted the expression levels of miR-29b and miR-129-5P.

Conclusions:

Matrine could inhibit LPS-induced EMT in HPMCs and reverse LPS inhibited expressions of miR-29 b and miR-129-5P in HPMCs, ultimately reduce peritoneal fibrosis. These findings provide a potential theoretical basis for using matrine in the prevention and treatment of peritoneal fibrosis.

Prevalence of impaired renal function among rural and urban populations: findings of a cross-sectional study in Malawi

Background: Sub-Saharan Africa faces region-specific risk factors for chronic kidney disease (CKD), such as nephrotoxic herbal medicines, antiretroviral therapy and infections, in addition to hypertension and diabetes. However, large epidemiological studies from this area are scarce. Methods: In a cross-sectional survey of non-communicable diseases, we conducted a prevalence sub-study of CKD in two Malawian populations. Study participants (N=5264) of 18 years of age and above were recruited and data on demographics and CKD risk factors were collected. Glomerular filtration rate was estimated (eGFR) using the CKD-EPI equation. Results: The prevalence of eGFR<60ml/min/1.73m 2 was 1.4% (95% CI 1.1 - 1.7%) and eGFR<90ml/min/1.73m 2 was 20.6% (95% CI 19.5 - 21.7%). The rural area had higher age-standardized prevalence of both eGFR<60ml/min/1.73m 2, at 1.8% (95% CI 1.4 - 2.3) and eGFR <90 ml/min/1.73m², at 21.1% (95% CI 19.9 - 22.3), than urban location, which had a prevalence of 1.5%, (95% CI 1.0 - 2.2) and 19.4% (95% CI 18.0 - 20.8), respectively, with overlapping confidence intervals. The prevalence of CKD was lower in females than in males in both rural and urban areas. Older age (p < 0.001), a higher level of education (p = 0.03) and hypertension (p < 0.001) were associated with a higher adjusted odds ratio (aOR) of low eGFR. Diabetes was associated with a reduced aOR of eGFR<90ml/min/1.73m 2 of 0.69 (95% CI 0.49-0.96; p=0.03). Of participants with eGFR<60ml/min/1.73m 2, 14 (19.4%) had no history of hypertension, diabetes or HIV, while 36 (50%) had a single risk factor of being hypertensive. Conclusion s: Impaired renal function is prevalent, but lower than expected, in rural and urban Malawi. Further research is needed to increase understanding of CKD incidence, survival and validation of eGFR calculations in this population.

Where Are You Going, Nephrology? Considerations on Models of Care in an Evolving Discipline

Nephrology is a complex discipline, including care of kidney disease, dialysis, and transplantation. While in Europe, about 1:10 individuals is affected by chronic kidney disease (CKD), 1:1000 lives thanks to dialysis or transplantation, whose costs are as high as 2% of all the health care budget. Nephrology has important links with surgery, bioethics, cardiovascular and internal medicine, and is, not surprisingly, in a delicate balance between specialization and comprehensiveness, development and consolidation, cost constraints, and competition with internal medicine and other specialties. This paper proposes an interpretation of the different systems of nephrology care summarising the present choices into three not mutually exclusive main models (“scientific”, “pragmatic”, “holistic”, or “comprehensive”), and hypothesizing an “ideal-utopic” prevention-based fourth one. The so-called scientific model is built around kidney transplantation and care of glomerulonephritis and immunologic diseases, which probably pose the most important challenges in our discipline, but do not mirror the most common clinical problems. Conversely, the pragmatic one is built around dialysis (the most expensive and frequent mode of renal replacement therapy) and pre-dialysis treatment, focusing attention on the most common diseases, the holistic, or comprehensive, model comprehends both, and is integrated by several subspecialties, such as interventional nephrology, obstetric nephrology, and the ideal-utopic one is based upon prevention, and early care of common diseases. Each model has strength and weakness, which are commented to enhance discussion on the crucial issue of the philosophy of care behind its practical organization. Increased reflection and research on models of nephrology care is urgently needed if we wish to rise to the challenge of providing earlier and better care for older and more complex kidney patients with acute and chronic kidney diseases, with reduced budgets.

Getting to know the enemy better-the global burden of chronic kidney disease

A good understanding of disease burden is the first step in formulating a response to it. Analysis of the Global Burden of Disease 2016 dataset shows an 87% rise in the global burden of chronic kidney disease and a doubling of chronic kidney disease deaths between 1990 and 2016. Countries with a lower level of socioeconomic development and poorer access to quality health care experience a higher chronic kidney disease burden. Reductions in global disability-adjusted life-years over time indicate progress, but deviations from this trend in some geographies present a call to action.

Impact of a single eGFR and eGFR-estimating equation on chronic kidney disease reclassification: a cohort study in primary care

Background

Chronic kidney disease (CKD) is diagnosed using the estimated glomerular filtration rate (eGFR) and the urinary albumin:creatinine ratio (ACR). The eGFR is calculated from serum creatinine levels using the Modification of Diet in Renal Disease (MDRD) or Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations.

Aim

To compare the performance of one versus two eGFR/ACR measurements, and the impact of equation choice, on CKD diagnosis and classification.

Design and setting

Cohort study in primary care in the Thames Valley region of the UK.

Method

Data were from 485 participants aged >60 years in the Oxford Renal Cohort Study with at least two eGFR tests. The proportion of study participants diagnosed and classified into different CKD stages using one and two positive tests were compared. Prevalence of CKD diagnosis and classification by CKD stage were compared when eGFR was calculated using MDRD and CKD-EPI equations.

Results

Participants included in the analysis had a mean age of 72.1 (±6.8) years and 57.0% were female. Use of a single screening test overestimated the proportion of people with CKD by around 25% no matter which equation was used, compared with the use of two tests. The mean eGFR was 1.4 ml/min/1.73 m² (95% CI = 1.1 to 1.6) higher using the CKD-EPI equation compared with the MDRD equation. More patients were diagnosed with CKD when using the MDRD equation, compared with the CKD-EPI equation, once (64% versus 63%, respectively) and twice (39% versus 38%, respectively), and 16 individuals, all of who had CKD stages 2 or 3A with MDRD, were reclassified as having a normal urinary ACR when using the CKD-EPI equation.

Conclusion

Current guidance to use two eGFR measures to diagnose CKD remains appropriate in an older primary care population to avoid overdiagnosis. A change from MDRD to CKD-EPI equation could result in one in 12 patients with a CKD diagnosis with MDRD no longer having a diagnosis of CKD.

Managing diabetic kidney disease

INTRODUCTION

Diabetes mellitus (DM) is the leading cause of chronic kidney disease (CKD). This review covers the pillars of care essential for the management of diabetic kidney disease (DKD) including (1) early diagnosis, (2) improved glycaemic control, (3) treatment of hypertension, (4) identification and treatment of associated metabolic bone disease and (5) identification and effective management of dyslipidaemia and additional cardiovascular risk factors.

SOURCES OF DATA

We searched PubMed for articles using search terms: diabetic nephropathy, diabetic kidney disease, diabetes and chronic kidney disease. We used clinical guidelines from NICE, the Association of British Clinical Diabetologists (ABCD), the Joint British Societies (JBS) and the Kidney Disease: Improving Global Outcomes (KDIGO) working group.

AREAS OF AGREEMENT

Multiple risk factor reduction targeting glycaemic control, blood pressure control, dyslipidaemia, smoking and management of obesity is important in preventing and in managing DKD.

AREAS OF CONTROVERSY

Guidelines disagree on the individualized glycaemic targets for patients with diabetic kidney disease.

GROWING POINTS

The growing number of patients with DKD is causing increased pressure on limited primary care and specialized services. New ways of managing patients using novel technology solutions are required.

AREAS TIMELY FOR DEVELOPMENT

The use of novel anti-hyperglycaemic agents, particularly sodium glucose co-transporter 2 inhibitors and GLP-1 receptor agonists, has been associated with a reduction in cardiovascular disease and DKD.

Longitudinal assessment of rabbit renal fibrosis induced by unilateral ureteral obstruction using two-dimensional susceptibility weighted imaging

BACKGROUND

Previous studies indicated that two-dimensional-susceptibility weighted imaging (2D-SWI) could serve as a useful biomarker for differentiating the grade of liver fibrosis.

PURPOSE

To evaluate the feasibility of 2D-SWI in the dynamic quantification of renal fibrosis in a rabbit model.

STUDY TYPE

Longitudinal study.

ANIMAL MODEL

Twenty-Four New Zealand White Rabbits including control group (n = 4); and renal fibrosis group (n = 20), by means of a unilateral ureteral obstruction (UUO) model.

FIELD STRENGTH/SEQUENCE

The 3.0 T SWI using a 2D gradient-echo sequence.

ASSESSMENT

The relative SWI signal ratio(r) of cortical and medulla (r = SI_renal /SI_muscle ) was longitudinally assessed before ligation and on weeks 2, 4, 6, and 8 following ligation. Sirius Red staining was used to assess the degree of fibrosis in five high-power fields.

STATISTICAL TESTS

The repeated measures of analysis of variance and linear regression analysis.

RESULTS

Both the cortical and medullary r values were significantly higher in the UUO kidneys at week 2 compared with the kidneys before ligation. Over the course of UUO progression, significant changes occurred in the cortical and medullary r values in vivo and fibrosis scores in vitro (all P values < 0.05). The r values gradually decreased, while the fibrosis scores gradually increased over 8 weeks following ligation. The linear regression analysis showed a strong and significant correlation between cortical and medullary r values and the pathologic fibrosis scores (R²  = 0.91, 0.81, respectively).

DATA CONCLUSION

The SWI sequence could provide a quantitative evaluation of renal fibrosis during UUO progression.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:1572-1577.

The clinical utility and cost impact of cystatin C measurement in the diagnosis and management of chronic kidney disease: A primary care cohort study

BACKGROUND

To reduce over-diagnosis of chronic kidney disease (CKD) resulting from the inaccuracy of creatinine-based estimates of glomerular filtration rate (GFR), UK and international guidelines recommend that cystatin-C-based estimates of GFR be used to confirm or exclude the diagnosis in people with GFR 45-59 ml/min/1.73 m2 and no albuminuria (CKD G3aA1). Whilst there is good evidence for cystatin C being a marker of GFR and risk in people with CKD, its use to define CKD in this manner has not been evaluated in primary care, the setting in which most people with GFR in this range are managed.

METHODS AND FINDINGS

A total of 1,741 people with CKD G3a or G3b defined by 2 estimated GFR (eGFR) values more than 90 days apart were recruited to the Renal Risk in Derby study between June 2008 and March 2010. Using Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations, we compared GFR estimated from creatinine (eGFRcreat), cystatin C (eGFRcys), and both (eGFRcreat-cys) at baseline and over 5 years of follow-up. We analysed the proportion of participants with CKD G3aA1 reclassified to 'no CKD' or more advanced CKD with the latter two equations. We further assessed the impact of using cystatin-C-based eGFR in risk prediction equations for CKD progression and all-cause mortality and investigated non-GFR determinants of eGFRcys. Finally, we estimated the cost implications of implementing National Institute for Health and Care Excellence (NICE) guidance to use eGFRcys to confirm the diagnosis in people classified as CKD G3aA1 by eGFRcreat. Mean eGFRcys was significantly lower than mean eGFRcreat (45.1 ml/min/1.73 m2, 95% CI 44.4 to 45.9, versus 53.6 ml/min/1.73 m2, 95% CI 53.0 to 54.1, P < 0.001). eGFRcys reclassified 7.7% (50 of 653) of those with CKD G3aA1 by eGFRcreat to eGFR ≥ 60 ml/min/1.73 m2. However, a much greater proportion (59.0%, 385 of 653) were classified to an eGFR category indicating more severe CKD. A similar pattern was seen using eGFRcreat-cys, but lower proportions were reclassified. Change in eGFRcreat and eGFRcys over 5 years were weakly correlated (r = 0.33, P < 0.001), but eGFRcys identified more people as having CKD progression (18.2% versus 10.5%). Multivariable analysis using eGFRcreat as an independent variable identified age, smoking status, body mass index, haemoglobin, serum uric acid, serum albumin, albuminuria, and C reactive protein as non-GFR determinants of eGFRcys. Use of eGFRcys or eGFRcreat-cys did not improve discrimination in risk prediction models for CKD progression and all-cause mortality compared to similar models with eGFRcreat. Application of the NICE guidance, which assumed cost savings, to participants with CKD G3aA1 increased the cost of monitoring by £23 per patient, which if extrapolated to be applied throughout England would increase the cost of testing and monitoring CKD by approximately £31 million per year. Limitations of this study include the lack of a measured GFR and the potential lack of ethnic diversity in the study cohort.

CONCLUSIONS

Implementation of current guidelines on eGFRcys testing in our study population of older people in primary care resulted in only a small reduction in diagnosed CKD but classified a greater proportion as having more advanced CKD than eGFRcreat. Use of eGFRcys did not improve risk prediction in this population and was associated with increased cost. Our data therefore do not support implementation of these recommendations in primary care. Further studies are warranted to define the most appropriate clinical application of eGFRcys and eGFRcreat-cys.