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

Incident chronic kidney disease among Canadian immigrants: a population-based cohort study

Introduction

A 'healthy immigrant effect' has been demonstrated for a number of chronic health conditions including cardiovascular disease, diabetes mellitus and dementia; however, the link between immigrant status and kidney health remains uncertain. We sought to compare the risk for incident chronic kidney disease (CKD) between Canadian immigrants and non-immigrants.

Methods

We conducted a population-level, observational cohort study of all adult (≥18 years of age) Ontario residents, including foreign-born immigrant Canadian citizens and non-immigrant Canadian citizens by birth, with normal baseline kidney function (outpatient estimated glomerular filtration rate (eGFR) ≥70 mL/min/1.73 m2) between 1 April 2007 and 30 September 2020 using provincial health administrative data. Multivariable Cox proportional hazard regression modelling was used to evaluate the relationship between immigrant status and the development of incident CKD (outpatient eGFR <60 mL/min/1.73m2).

Results

The study cohort included 10 440 210 Ontario residents, consisting of 22% immigrants (n=2 253 360) and 78% (n=8 186 850) non-immigrants. The mean (SD) age and eGFR were 45 (17) years and 102 (16) mL/min/1.73 m2, respectively, and 54% of individuals were female. A total of 117 028 immigrants (5%, 7 events per 1000 person-years) and 984 277 non-immigrants (12%, 16 events per 1000 person-years) developed incident CKD during follow-up. Immigrants experienced a 20% lower risk for incident CKD compared with non-immigrants (adjusted HR 0.80, 95% CI 0.80 to 0.81). Consistent findings were seen for refugee and non-refugee immigrants, immigrants with remote (1985-2004) and recent (2005-2020) landing dates, and immigrants from different world regions. Results were similar on re-defining incident CKD as two outpatient eGFR measurements <60 mL/min/1.73 m2 at least 90 days apart, treating death as a competing risk, and adjusting for baseline albuminuria.

Conclusion

Immigrants experience a lower risk for incident CKD compared with non-immigrants. These findings provide evidence of a 'healthy immigrant effect' in relation to kidney health.

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.

A 5-Year Follow-Up Study to Explore Factors Associated with Rapid Kidney Function Decline Among Bus Drivers

Background

Owing to the stressful occupational characteristics, bus drivers have been reported to have a higher risk of renal dysfunction. However, the related factors associated with rapid kidney function decline among bus drivers have not been explored in the existing literature. Therefore, our research aimed to investigate factors related with rapid kidney function decline, and to explore the correlation of baseline SUA (serum uric acid), longitudinal changes in SUA, and rapid eGFR (estimated glomerular filtration rate) decline for bus drivers.

Methods

This was a five-year cohort study in Shenzhen, China, between 2017 and 2021. We included 832 bus drivers with normal kidney function at baseline. Study subjects were stratified into four quartiles of change in eGFR, and rapid eGFR decline was regarded as the highest (4th) quartile of ΔeGFR (eGFR in 2017-eGFR in 2021). Univariable and multivariable logistic regressions were conducted to explore factors affecting rapid eGFR decline.

Results

The incidence of hyperuricemia among bus drivers was 37.7% in 2017 and 40.5% in 2021. The overall subjects had a median 5-year decrease in eGFR of 6.72 mL/min/1.73 m2, and individuals with increased SUA from normal to hyperuricemia group had the greatest decline of eGFR. Multivariate analysis showed bus drivers' age (Odds radio: OR, 1.04), elevated baseline eGFR (OR, 1.08), and SUA increase (OR, 1.38) were significantly associated with rapid eGFR changes.

Conclusion

The high prevalence of hyperuricemia among bus drivers should warrant more attention from health professionals. Subjects' age, elevated baseline eGFR, and SUA increase were risk factors for rapid eGFR decline over 5-year. The findings can provide significant evidence for timely prevention and intervention to decrease the incidence of rapid renal function decline among bus drivers.

Global, regional, and national burden of kidney dysfunction from 1990 to 2019: a systematic analysis from the global burden of disease study 2019

OBJECTIVE

We aim to explore the prevalence and temporal trends of the burden of kidney dysfunction (KD) in global, regional and national level, since a lack of related studies.

DESIGN

Cross-sectional study.

MATERIALS

The data of this research was obtained from Global Burden of Diseases Study 2019. The estimation of the prevalence, which was measured by the summary exposure value (SEV), and attributable burden of KD was performed by DisMod-MR 2.1, a Bayesian meta-regression tool. The Spearman rank order correlation method was adopted to perform correlation analysis. The temporal trends were represented by the estimated annual percentage change (EAPC).

RESULTS

In 2019, there were total 3.16 million deaths and 76.5 million disability-adjusted life years (DALYs) attributable to KD, increased by 101.1% and 81.7% compared with that in 1990, respectively. From 1990 to 2019, the prevalence of KD has increased in worldwide, but decreased in High-income Asia Pacific. Nearly 48.5% of countries globally, such as South Africa, Egypt and Mexico had increased mortality rates of KD from 1990 to 2019 while 44.6% for disability rate. Countries with lower socio-demographic index (SDI) are facing a higher prevalence as well as mortality and disability rate compared with those with higher SDI. Compared with females, the prevalence of KD was lower in males, however the attributable mortality and disability rate were higher in all years from 1990 to 2019.

CONCLUSION

With the progress of senescent, we will face more severe challenges of reducing the prevalence and attributable burden of KD, especially in regions with lower SDI. Effective measures are urgently required to alleviate the prevalence and burden of KD.

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.

Decreased renal function is associated with incident dementia: An IMRD-THIN retrospective cohort study in the UK

INTRODUCTION

Decreased renal function is a potential risk factor for dementia.

METHODS

This retrospective cohort study of 2.8 million adults aged ≥50 years used the IMRD-THIN database, representative of UK primary care, from January 1, 1995 to February 24, 2020. The associations between estimated glomerular filtration rate (eGFR) and urine albumin creatinine ratio (ACR) with incident all-cause dementia were analyzed using Cox regression.

RESULTS

In the eGFR cohort (n = 2,797,384), worsening renal dysfunction was associated with increased hazard of all-cause dementia, with greatest hazard at eGFR 15-30 ml/min/1.73min² (hazard ratio [HR] 1.26, 95% confidence interval [CI] 1.19-1.33). In the ACR cohort (n = 641,912), the hazard of dementia increased from ACR 3-30 mg/mmol (HR 1.13, 95% CI 1.10-1.15) to ACR > 30 mg/mmol (HR 1.25, 95% CI 1.18-1.33).

DISCUSSION

Worsening eGFR and albuminuria have graded associations with the risk of dementia, which may have significant implications for the care of patients with kidney disease.

A follow-up study to explore factors associated with rapid kidney function decline and new-onset kidney disease among Chinese elderly population

AIM

To explore potential factors associated with rapid kidney function decline and new-onset kidney disease among a Chinese elderly population, and to examine the relationships between baseline serum uric acid (SUA), longitudinal change in SUA and rapid estimated glomerular filtration rate (eGFR) decline over 5 years for this Chinese elderly population.

METHODS

A 5-year follow-up study was conducted from 2016 to 2020 in Xiamen City, China; and 2436 elderly people with normal kidney function at baseline was included. The multivariable logistic regressions were used to explore risk factors for rapid eGFR decline and new-onset kidney disease.

RESULTS

The median age of subjects was 65 years, and 38.5% were men. These elderly people experienced a median 5-year decrease in eGFR of 14.50 mL/min/1.73 m² , and 11.2% of them had developed new-onset kidney disease after 5-year follow-up. Participants with elevated SUA change from the normal group to the hyperuricemia group witnessed the highest decrease of eGFR after a 5-year follow-up than other groups. Multivariate analysis found advanced age, female, elevated baseline SUA, elevated SUA change, hypertension and triglyceride-glucose index were risk factors for rapid eGFR decline and new-onset kidney disease.

CONCLUSION

The Chinese elderly population was more likely to encounter rapid renal function decline and new-onset kidney disease. A regular test for kidney disease was strongly recommended for these elderly people who were female, with advanced age, with elevated baseline SUA and elevated SUA change; and had high levels of insulin resistance, and blood pressure. The derived findings can offer significant evidence for targeted prevention for the Chinese elderly population. Geriatr Gerontol Int ••; ••: ••-•• Geriatr Gerontol Int 2022; ••: ••-••.

Sex-specific associations between potassium intake, blood pressure, and cardiovascular outcomes: the EPIC-Norfolk study

AIMS

A potassium replete diet is associated with lower blood pressure (BP) and lower risk of cardiovascular disease (CVD). Whether these associations differ between men and women and whether they depend on daily sodium intake is unknown.

METHODS AND RESULTS

An analysis was performed in 11 267 men and 13 696 women from the EPIC-Norfolk cohort. Twenty-four hour excretion of sodium and potassium, reflecting intake, was estimated from sodium and potassium concentration in spot urine samples using the Kawasaki formula. Linear and Cox regression were used to explore the association between potassium intake, systolic BP (SBP), and CVD events (defined as hospitalization or death due to CVD). After adjustment for confounders, interaction by sex was found for the association between potassium intake and SBP (P < 0.001). In women, but not in men, the inverse slope between potassium intake and SBP was steeper in those within the highest tertile of sodium intake compared with those within the lowest tertile of sodium intake (P < 0.001 for interaction by sodium intake). Both in men and women, higher potassium intake was associated with a lower risk of CVD events, but the hazard ratio (HR) associated with higher potassium intake was lower in women than in men [highest vs. lowest potassium intake tertile: men: HR 0.93, 95% confidence interval (CI) 0.87-1.00; women: HR 0.89, 95% CI 0.83-0.95, P = 0.033 for interaction by sex].

CONCLUSION

The association between potassium intake, SBP, and CVD events is sex specific. The data suggest that women with a high sodium intake in particular benefit most from a higher potassium intake with regard to SBP.

R. S, Toh CC, Sundram M, Md Yusoff NA, Nagappan P, Kamaruzaman S, Yeoh WS, Ong TA, Lim J. Cardiovascular risk factors, ethnicity and infection stone are independent factors associated with reduced renal function in renal stone formers

BACKGROUND

Recent evidence suggested the link between nephrolithiasis and renal function impairment. We aimed to determine the renal function profile and potential factors associated with reduced renal function amongst renal stone formers in multi-ethnic Asians.

METHODS

We conducted a cross-sectional study involving patients undergoing percutaneous nephrolithotomy between May 2015 and December 2019. Reduced renal function was defined as having estimated glomerular filtration rate < 60 ml/min per 1.73 m2. Renal stone samples were collected and quantified using infrared spectroscopy. Potential factors associated with reduced renal function including age, ethnicity, educational level, history of diabetes, hypertension, gout, hydronephrosis, serum uric acid level, and type of renal stone were evaluated using univariable and multivariable analyses.

RESULTS

A total of 1162 patients from a multi-ethnic population (Malays 67%, Chinese 19%, Indians 13% and indigenous people 1%) with median age of 57 years (Interquartile range 48-64) were enrolled in the study. Almost a third of patients were found with reduced renal function. Multivariable analysis showed that the odds of having reduced renal function increased with age, ethnicity, lower educational level, history of diabetes, hypertension, gout, bilateral hydronephrosis, elevated serum uric acid level and infection stone.

CONCLUSIONS

Reduced renal function varies between ethnicities and all age groups of renal stone formers. In addition to age and ethnicity, cardiovascular risk factors including diabetes and hypertension may also need to be taken into account in managing stone patients with reduced renal function.

The Relationship Between Primary Knee Osteoarthritis and Aortic Stiffness, Distensibility, and Valve Calcifications: A Case-Control Study

OBJECTIVE

The purpose of our study was to evaluate aortic stiffness and distensibility changes and the presence of aortic and mitral valve calcifications in patients with primary knee osteoarthritis (OA), using 2-dimensional and Doppler transthoracic echocardiography.

METHODS

This case-control study included 115 participants with OA and a control group between May 2019 and November 2019. The Kellgren-Lawrence classification was used for the diagnosis and classification of knee OA, based on radiological images. We compared the demographic data, 2-dimensional and Doppler transthoracic echocardiography results, and laboratory findings between the OA patient group and the control group.

RESULTS

There was a significant difference between aortic strain, aortic distensibility, aortic stiffness, and C-reactive protein values between the OA patient group and the control group (p < 0.001 for all). Post hoc analyses revealed that aortic strain and aortic distensibility values were significantly lower, and aortic stiffness values were significantly higher in the grade 4 OA group than those of other groups (p < 0.05 for all). In addition, the C-reactive protein values of the grades 3 and 4 patients were significantly higher than those of other groups (p < 0.05 for all). No significant difference was observed between the groups in terms of aortic and mitral valve calcifications (p > 0.05 for all).

CONCLUSION

Aortic strain and distensibility values were lower in the advanced grades of primary knee OA, whereas aortic stiffness values and the frequency of valve calcifications were higher.

National Trends in the Prevalence of Chronic Kidney Disease Among Racial/Ethnic and Socioeconomic Status Groups, 1988-2016

IMPORTANCE

The overall prevalence of chronic kidney disease (CKD) has stabilized in the United States in recent years. However, it is unclear whether all major sociodemographic groups experienced this trend.

OBJECTIVE

To examine trends in CKD prevalence across major sociodemographic groups as defined by race/ethnicity and socioeconomic status.

DESIGN, SETTING, AND PARTICIPANTS

This repeated cross-sectional study used data from the National Health and Nutrition Examination Surveys for 1988 to 1994 and every 2 years from 1999 to 2016 on individuals 20 years or older with information on race/ethnicity, socioeconomic status, and serum creatinine levels. Statistical analysis was conducted from May 1, 2017, to April 6, 2020.

EXPOSURES

Race/ethnicity and socioeconomic status.

MAIN OUTCOMES AND MEASURES

Prevalence of CKD was defined as an estimated glomerular filtration rate of 15 to 59 mL/min/1.73 m2.

RESULTS

A total of 54 554 participants (mean [SE] age, 46.2 [0.2] years; 51.7% female) were examined. The age-, sex- and race/ethnicity-adjusted overall prevalence of stage 3 and 4 CKD increased from 3.9% in 1988-1994 to 5.2% in 2003-2004 (difference, 1.3%; 95% CI, 0.9%-1.7%; P < .001 for change) and remained relatively stable thereafter at 5.1% in 2015-2016 (difference, -0.1%; 95% CI, -0.7% to 0.4%; P = .61 for change). The trend in adjusted CKD prevalence differed significantly by race/ethnicity (P = .009 for interaction). In non-Hispanic white and non-Hispanic black persons, CKD prevalence increased between 1988-1994 and 2003-2004 and remained stable thereafter. Among Mexican American persons, CKD prevalence was lower than in other racial/ethnic groups and remained stable between 1988-1994 and 2003-2004 but nearly doubled (difference, 2.1%; 95% CI, 0.9%-3.3%; P = .001 for change) between 2003-2004 and 2015-2016 to rates similar to those in other racial/ethnic groups. There were higher rates of CKD prevalence among groups with lower educational level and income (eg, 5.8% vs 4.3% and 4.3% vs 3.1% in low vs high education and income, respectively, in 1988-1994), but trends in CKD prevalence mirrored those for the overall population. The higher CKD prevalence among individuals with lower educational level and income remained largely consistent throughout the entire period. Results were similar in most subgroups when including albuminuria to define CKD.

CONCLUSIONS AND RELEVANCE

The prevalence of CKD in the United States has stabilized overall in recent years but has increased among Mexican American persons. More important, gaps in CKD prevalence across racial/ethnic groups and levels of socioeconomic status largely persisted over 28 years. There is a need to identify and address causes of increasing CKD prevalence among Mexican American persons and a need to renew efforts to effectively mitigate persistent disparities in CKD prevalence.

Helping people to live well with chronic kidney disease

Reduced glomerular filtration rate and presence of albuminuria are both associated with increased risk of several poor outcomes. People with chronic kidney disease also commonly suffer from lower quality of life than their age-matched peers. The experiences reported by patients with chronic kidney disease include being shocked by the diagnosis, being uncertain about the cause and worrying about progression and future treatment. Issues such as depression, pain and fatigue are common in people with chronic kidney disease. Helping people to live well with a long-term condition like chronic kidney disease should include efforts to reduce the risk of adverse events occurring in the future, and consider what can be done to enhance quality of life now. Clinicians can help by being aware of the patient perspective, communicating clearly and recommending interventions that reduce future risk as well as recognising and treating symptoms. Assessing overall treatment burden is an important component of management and non-pharmacological interventions that may improve mobility, strength and pain should be considered.

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.

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.

Kidney Disease and Anemia in Elderly Patients

Anemia is a very common complicating feature of chronic kidney disease (CKD) in the elderly. Noninvasive assessment of renal function in the elderly may include several equations although they may actually underestimate the true glomerular filtration rate (GFR). In summary, anemia in the setting of CKD in the elderly is generally underrecognized and undertreated, leading to associations of increased morbidity and mortality. The likelihood of benefits of treatment of anemia in this rapidly increasing subset of patients with CKD remains very high.

Phenotyping normal kidney function in elderly patients with type 2 diabetes: a cross-sectional multicentre study

AIMS

Type 2 diabetes (T2D) accelerates the decline in glomerular function; however, some individuals do not develop chronic kidney disease despite advanced age and long-lasting T2D. We aimed to phenotype patients with T2D aged 80 years or older who presented with a fully preserved kidney function.

METHODS

From an Italian population of 281,217 T2D outpatients, we collected data on demographics, anthropometrics, diabetes duration, HbA1c, fasting plasma glucose, lipids, liver enzymes, estimated glomerular filtration rate (eGFR), albumin excretion rate (AER), chronic complications, and medication use. We primarily compared patients with a fully preserved kidney function (eGFR > 90 ml/min/1.73 m² and AER < 30 mg/24 h, or G1A1) with those with mild kidney impairment (eGFR 60-90 ml/min/1.73 m² and AER < 30 mg/24 h, or G2A1).

RESULTS

N = 113,860 had available data for eGFR and AER, 21,648 of whom were aged ≥ 80. G1A1 (n = 278) and G2A1 (n = 6647) patients represented 1.3 and 30.7% of aged T2D patients, respectively, with an average diabetes duration of 16 years. Differences between the G1A1 and G2A1 groups were entered in a multiple logistic regression analysis with and without imputation of missing data. After adjustment and in both imputed and non-imputed datasets, younger age, lower BMI and lower triglycerides were associated with fully preserved versus mildly impaired kidney function. The comparison between G1A1 and G1A2/3 yielded different results.

CONCLUSIONS

In a rare population of patients with a fully preserved kidney function despite old age and long-lasting diabetes, lower BMI and triglycerides suggest that protection from lipotoxicity may preserve kidney function over time.