Lifetime Risk of Stage 3-5 CKD in a Community-Based Sample in Iceland

Current use of angiotensin II receptor blockers and angiotensin-converting enzyme inhibitors for hypertension in patients with chronic kidney disease with proteinuria: a cross-sectional study based on real-world data

Japanese guidelines recommend angiotensin II receptor blockers (ARBs) and angiotensin-converting enzyme inhibitors (ACEIs) as first-line therapy in hypertensive patients with chronic kidney disease (CKD) and proteinuria, but calcium channel blockers in patients with stage G4-5 CKD aged ≥75 years; however, the implementation of these guidelines in clinical practice is unclear. We investigated the actual use of these agents in this patient population. We conducted a cross-sectional study using the DeSC database, which includes anonymous information from various health insurance systems in Japan. A total of 34,362 hypertensive patients aged <75 years with CKD stage G1-G5 with urinary protein ≥1+ or aged ≥75 years with CKD stage G1-G3 with urinary protein ≥1+, for whom Japanese guidelines recommend first-line ARBs/ACEIs, were included in the analysis. Prescription rates of ARBs and ACEIs were calculated overall and separately for each age group and glomerular filtration rate category. The mean participant age was 65.8 ± 14.8 years, including 24,585 patients (72%) <75 years and 9777 (28%) ≥75 years. Of these, 9529 were prescribed ARBs/ACEIs (prescription rate 28%). The prescription rate was lower in patients aged <75 years with CKD stage G1-G5 (prescription rate 23%) compared with patients aged ≥75 years old with CKD stage G1-G3 (prescription rate 41%) (p < 0.001). Patients with CKD stage G1 had the lowest prescription rates for ARBs/ACEIs in both age categories. These results indicate that, despite guideline recommendations, ARBs/ACEIs are insufficiently prescribed for patients with hypertension associated with CKD with proteinuria. ARBs and ACEIs were only used in 28% of hypertensive patients aged<75 years (CKD stage G1-G5) or aged ⩾75 years (CKD stage G1-G3), with urinary protein ⩾1+, for whom Japanese guidelines recommend ARBs/ACEIs. The prescription rate was lower in the younger compared with the older patients.

Risk of incident chronic kidney disease among patients with urolithiasis: a nationwide longitudinal cohort study

Background

Urolithiasis has been infrequently implicated to have a causal association with chronic kidney disease (CKD). Recently, several studies have demonstrated the relationship between urolithiasis and CKD. However, the generalizability of their results is limited. This study aimed to investigate the association between urolithiasis and the risk of incident CKD.

Methods

This longitudinal cohort study used the National Health Insurance Service data, including 219 570 Korean adults with incident urolithiasis requiring procedural interventions and without prior kidney disease and 219 570 age- and sex-matched controls without urolithiasis between 1 January 2002 and 31 December 2020. Primary outcome was the development of CKD, defined by an estimated glomerular filtration rate <60 ml/min/1.73 m2 for at least two consecutive measurements at least 90 days apart. The risk for incident CKD was further examined using the outcome defined by newly occurring diagnostic codes indicating CKD.

Results

Over a mean follow-up of 6 years, 12 338 (2.8%) primary outcome events of CKD were observed (incidence rate 4.6/1000 person-years). Per multivariable Cox analysis, urolithiasis was associated with a higher risk of incident CKD [adjusted hazard ratio 1.41 (95% confidence interval 1.36-1.46)]. This association remained consistent across all clinically relevant subgroups and when the CKD outcome was defined based on the diagnostic codes in the sensitivity analysis.

Conclusions

In this large national cohort study, patients with urolithiasis were associated with a higher risk of incident CKD than those without urolithiasis. Further studies are warranted to establish the benefits of preventing urolithiasis in reducing CKD development.

Effects of a High-Protein Diet on Kidney Injury under Conditions of Non-CKD or CKD in Mice

Considering the prevalence of obesity and global aging, the consumption of a high-protein diet (HPD) may be advantageous. However, an HPD aggravates kidney dysfunction in patients with chronic kidney disease (CKD). Moreover, the effects of an HPD on kidney function in healthy individuals are controversial. In this study, we employed a remnant kidney mouse model as a CKD model and aimed to evaluate the effects of an HPD on kidney injury under conditions of non-CKD and CKD. Mice were divided into four groups: a sham surgery (sham) + normal diet (ND) group, a sham + HPD group, a 5/6 nephrectomy (Nx) + ND group and a 5/6 Nx + HPD group. Blood pressure, kidney function and kidney tissue injury were compared after 12 weeks of diet loading among the four groups. The 5/6 Nx groups displayed blood pressure elevation, kidney function decline, glomerular injury and tubular injury compared with the sham groups. Furthermore, an HPD exacerbated glomerular injury only in the 5/6 Nx group; however, an HPD did not cause kidney injury in the sham group. Clinical application of these results suggests that patients with CKD should follow a protein-restricted diet to prevent the exacerbation of kidney injury, while healthy individuals can maintain an HPD without worrying about the adverse effects.

Global, regional, and national burden of chronic kidney disease attributable to high sodium intake from 1990 to 2019

Background

High sodium intake is a crucial risk factor for the development and progression of chronic kidney disease (CKD). However, the latest global spatiotemporal patterns of CKD burden attributable to high sodium intake still remain unclear. We aimed to evaluate the level and trends of the CKD burden associated with high sodium intake according to sex, age, socio-demographic index (SDI), region, and country from 1990 to 2019.

Methods

Data on CKD burden attributable to high sodium intake from 1990 to 2019 were extracted from the Global Burden of Disease (GBD) Study 2019. The CKD-related deaths, disability-adjusted life years (DALYs), age-standardized mortality rate (ASMR), and age-standardized DALYs rate (ASDR) attributable to high sodium intake were estimated by age, sex, SDI, region, and country. The estimated annual percentage change (EAPC) was calculated to evaluate the secular trends of ASMR and ASDR of CKD attributable to high sodium intake from 1990 to 2019. We further explored the associations of SDI with the ASMR and ASDR of CKD attributable to high sodium intake.

Results

Globally, the number of CKD-related deaths and DALYs attributable to high sodium intake were 45,530 (95% UI: 12,640 to 93,830) and 1.32 million (95% UI: 0.43 to 2.8) in 2019, both twice as many as those in 1990. However, the ASMR and ASDR slightly grew, with an EAPC of 0.22 (95% CI: 0.16 to 0.28) and 0.10 (95% CI: 0.04 to 0.16), respectively. The age-specific numbers and rates of deaths, as well as DALYs of CKD attributable to high sodium intake, rose with age and were greater in males than in females. The rates of deaths and DALYs peaked in the >95 age group for both females and males in 2019. From 1990 to 2019, the trends of both age-specific rates of mortality and DALYs of CKD attributable to high sodium intake were down in people under 60, while in people over 60, the trends were the opposite. The burden of CKD attributable to high sodium intake in 2019 and its temporal trends from 1990 to 2019 varied greatly by SDI quintile and geographic location. The ASMR or ASDR showed a non-linear negative correlation with SDI at the regional level. The EAPC in ASMR or ASDR showed a markedly negative correlation with ASMR or ASDR in 1990, with a coefficient of -0.40. Nevertheless, the EAPC in ASMR rather than ASDR was positively correlated with SDI in 2019, with a coefficient of 0.18.

Conclusion

Our findings suggest that there are significant sexual and geographic variations in the burden of CKD attributable to high sodium intake and its temporal trends. Globally, the high sodium intake-caused CKD burden continues to elevate, posing a major challenge to public health. In response to this, strengthened and tailored approaches for CKD prevention and sodium intake management are needed, especially for elderly populations, males, and the population in the middle SDI regions.

Benchmarking CKD: incidence of CKD in a European country with low prevalence of CKD and kidney replacement therapy

Iceland was one of six European countries with an adjusted incidence of kidney replacement therapy (KRT) in 2018 lower than 100 per million persons (pmp), along with Estonia, Montenegro, Russia, Serbia and Finland. It was also one of 10 countries with an adjusted KRT prevalence <900 pmp. Furthermore, the prevalence of chronic kidney disease (CKD) in Iceland is up to 2.44-fold lower and the death rate from CKD up to 3.44-fold lower than in other countries with a low incidence of KRT, suggesting that the low KRT incidence actually reflects a low need for KRT rather than low uptake or availability of KRT. This identifies Iceland as a benchmark for countries trying to reduce KRT incidence. Iceland also represents one of the best genetically characterized populations in the world, facilitating studies on the influence of the genetic background versus environment and lifestyle on CKD. This issue of CKJ reports the incidence and risk factors for CKD in Icelandic adults. Diabetes, acute kidney injury, hypertension, cardiovascular disease, chronic lung disease, malignancy and major psychiatric illness were associated with an increased risk of incident CKD, as were obesity and sleep apnea in women. However, in 75% of incident CKD cases, CKD was first detected in category G3 or higher, emphasizing the need for new tools that allow an earlier diagnosis of CKD that precedes the loss of >50% of the functioning kidney mass and/or wider use of albuminuria as a screening tool. The European Society of Cardiology just recommended assessing albuminuria for routine cardiovascular risk workups for all.

The Other Way Around: Living With Chronic Kidney Disease From the Perspective of Men

A wealth of evidence has suggested sex (biological) and gender (sociocultural) differences in the prevalence, progression, and outcomes of persons with chronic kidney disease. Much of this evidence tends to emphasize differences in which women are disadvantaged, and less attention is paid to findings in which women are better off or similar to men. However, gender medicine recognizes that men and women have different disease determinants, presentation, and attitudes, and it pertains to both sexes. In this review, we revisit chronic kidney disease through the perspective of men, and illustrate a population segment at need of stringent preventative and management strategies.

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.

Preoperative renal function affects outcomes of surgery for aortic arch aneurysm in the elderly

OBJECTIVES

This study aimed to determine the optimal surgical procedure for arch aneurysm in the elderly based on preoperative comorbidities, especially focusing on renal function.

METHODS

The medical records of 374 patients who experienced arch surgery between 2008 and 2019 were reviewed. Among the 374 patients, 92 who underwent total arch replacement (TAR) were assigned to the TAR group and the remaining 152 who underwent debranching thoracic endovascular aortic repair (DTEVAR) were assigned to the DTEVAR group.

RESULTS

Chronic kidney disease (CKD) was an independent risk factor of mortality (hazard ratio, 2.85; p = 0.029) in the TAR group but not in the DTEVAR. In the Grade I/II category CKD (estimated glomerular filtration rate (eGFR) > 60 mL/min), freedom from all-cause mortality was significantly higher in the TAR group than in the DTEVAR group (p = 0.0155, log-rank). Freedom from all-cause mortality was comparable between the two groups in the Grade IIIa CKD (eGFR, 45-60) (p = 0.584, log-lank), Grade IIIb (eGFR, 30-45) (p = 0.822), and Grade IV/V (eGFR < 30) (p = 0.548).

CONCLUSION

In elderly patients who underwent TAR, CKD was the independent risk factor of the mortality, but not in the patients who underwent debranching TEVAR. Conversion of surgical strategy from TAR to debranching TEVAR in the treatment of aortic arch aneurysms in the elderly with CKD below Grade IIIa is acceptable considering that less-invasiveness. While, in the elderly with Grade I/II CKD, TAR still remains as a primary choice for the arch repair for better mid-term survival.

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.

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.

Widening the lens to childhood: relevance and lifetime risk of kidney failure

PURPOSE OF REVIEW

Lifetime risk of outcomes is emerging as a highly relevant health indicator, even in the context of low absolute risk of disease progression in short time frames. Evidence to support this concept for kidney failure is increasing, with growing emphasis on the long-term impact of risk factors occurring early in life.

RECENT FINDINGS

Proteinuria and stage of chronic kidney disease (CKD) are now established predictors of CKD progression in children, and youth with type 2 diabetes are emerging as a group at significant risk. Recent population-based studies have also examined the lifetime risk of end-stage renal disease in individuals with any childhood CKD. A recent study found that even in the absence of biomarkers of renal injury, childhood CKD can increase the lifetime risk of end-stage renal disease four-fold, and up to 10-fold in adults less than 40 years of age.

SUMMARY

Children with CKD are at high lifetime risk of kidney failure and require follow-up. Identifying children at highest lifetime risk through the use of biomarkers and risk equations, and determining the optimal duration and intensity of follow-up requires further research.

Survivability of hospitalized chronic kidney disease (CKD) patients with moderate to severe estimated glomerular filtration rate (eGFR) after experiencing adverse drug reactions (ADRs) in a public healthcare center: a retrospective 3 year study

Background

Accurate identification and routine preventive practices are crucial steps in lessening the incidence of medications and patients related adverse drug reactions (ADRs).

Methods

Three years retrospective study was conducted among chronic kidney disease (CKD) patients at multi-wards in a tertiary healthcare center. Data collected included demographic characteristics, physical examination results, comorbid conditions, laboratory tests and medications taken. Only medication prescribed during the hospital stay were considered in this study.

Results

From this study only one ADR incident was definitely preventable and majority of other ADRs (88.3%) were possibly preventable. Type of renal replacement therapy (p = 0.023) and stages of renal function (p = 0.002) were significantly associated with survivability of the hospitalized CKD patients after ADRs. Highest percentage of mortality based on categories were 50–59 years (20.0%), male (16.3%), Indian ethnicity (23.7%), obese (15.0%), smoking (17.1%), consumes alcohol (17.4%), conservative management of renal disease (19.5%) and renal function of < 15 mL/min/1.73m². Overall survivability using Kaplan-Meier analysis reported a significant difference of 18-day survival rate between patients undergoing hemodialysis and patients conservatively managing their renal disease. The 18 days survival rate of patients undergoing hemodialysis, peritoneal dialysis and conservative management were 94.9%, 91.7% and 75.1% respectively. Eighteen days survival rate of patients with renal functions of 30–59 mL/min/1.73m², 15–29 mL/min/1.73m² and < 15 mL/min/1.73m² were 87.4%, 69.8% and 88.6% respectively. Similarly, Cox regression analysis revealed that renal replacement therapy was the only factor significantly contributed to ADRs related mortality. CKD patients whom conservatively managed renal disease or/and with renal function of < 15 mL/min/1.73m² had 5.61 and 5.33 higher mortality risk respectively.

Conclusion

Majority of the reported ADRs were possibly preventable. Renal replacement therapy and/or renal function were significant risk factors for mortality due to ADRs among hospitalized CKD patients stages 3 to 5. Clinician engagement, intensive resources and regular updates aided with online monitoring technology are needed for enhancing care and prevention of ADRs among CKD patients.

Residual lifetime risk of chronic kidney disease

Background

An accurate estimation of the lifetime risk of chronic kidney disease (CKD) can aid in patient education while also informing the development of public health screening programs and educational campaigns.

Methods

Framingham Offspring Study participants were included if they were free of CKD (estimated glomerular filtration rate <60 mL/min/1.73 m2) at age 50 years and had at least two serum creatinine measures during follow-up (mean 16 years, 49 506 person-years). We estimated the lifetime risk of CKD to age 90 years adjusting for the competing risk of death in the overall cohort and in population subgroups with known CKD risk factors including hypertension, obesity and diabetes.

Results

Overall 3362 individuals (52% women) were included in the study. Mean age at study baseline was 54 years. By the end of the study, 729 individuals (21.7%) developed CKD and 618 (18.4%) died. At age 50 years, the cumulative lifetime risk of CKD was 41.3% [95% confidence interval (CI) 38.5-44.0]. The risk was increased in those with risk factors at baseline including diabetes (52.6%, 95% CI 44.8-60.4), hypertension (50.2%, 95% CI 46.1-54.3) and obesity (46.5%, 95% CI 41.1-52.0). For those individuals without any risk factors at baseline, the lifetime risk of CKD was lower (34.2%, 95% CI 29.4-39.0) relative to those with 1, 2 or 3 risk factors (45.0, 51.5 and 56.1% respectively, P < 0.01 for all compared with those with no risk factors).

Conclusions

Four out of 10 individuals without CKD at age 50 years will eventually develop CKD. This risk is modified by the presence of hypertension, diabetes and obesity at baseline. This demonstrates the importance of early identification of CKD risk factors, to aid in patient education, and potentially to reduce the future risk of disease.

Why overestimate or underestimate chronic kidney disease when correct estimation is possible?

There is no doubt that the introduction of the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines 14 years ago, and their subsequent updates, have substantially contributed to the early detection of different stages of chronic kidney disease (CKD). Several recent studies from different parts of the world mention a CKD prevalence of 8-13%. However, some editorials and reviews have begun to describe the weaknesses of a substantial number of studies. Maremar (maladies rénales chroniques au Maroc) is a recently published prevalence study of CKD, hypertension, diabetes and obesity in a randomized, representative and high response rate (85%) sample of the adult population of Morocco that strictly applied the KDIGO guidelines. When adjusted to the actual adult population of Morocco (2015), a rather low prevalence of CKD (2.9%) was found. Several reasons for this low prevalence were identified; the tagine-like population pyramid of the Maremar population was a factor, but even more important were the confirmation of proteinuria found at first screening and the proof of chronicity of decreased estimated glomerular filtration rate (eGFR), eliminating false positive results. In addition, it was found that when an arbitrary single threshold of eGFR (<60 mL/min/1.73 m2) was used to classify CKD stages 3, 4 and 5, it lead to substantial 'overdiagnosis' (false positives) in the elderly (>55 years of age), particularly in those without proteinuria, haematuria or hypertension. It also resulted in a significant 'underdiagnosis' (false negatives) in younger individuals with an eGFR >60 mL/min/1.73 m2 and below the third percentile of their age-/gender-category. The use of the third percentile eGFR level as a cut-off, based on age-gender-specific reference values of eGFR, allows the detection of these false positives and negatives. There is an urgent need for additional quality studies of the prevalence of CKD using the recent KDIGO guidelines in the correct way, to avoid overestimation of the true disease state of CKD by ≥50% with potentially dramatic consequences.

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

The introduction of the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines has substantially contributed to the early detection of different stages of chronic kidney disease (CKD). Several recent studies from different parts of the world mention a CKD prevalence of between 8 and 13%. There are several reasons the CKD prevalence found in a study of a particular population is clearly overestimated. The structure of the population pyramid (young or older age) of the study sample may result in high or low CKD prevalence. The absence of using an isotope dilution mass spectrometry creatinine assay can be the source of high bias in CKD prevalence. In addition, using an arbitrary single threshold of estimated glomerular filtration rate (eGFR; <60 mL/min/1.73 m2) for classifying CKD leads to a substantial 'overdiagnosis' (false positives) in the elderly (>65 years of age), particularly in those without albuminuria (or proteinuria), haematuria or hypertension. It also results in a significant 'underdiagnosis' (false negatives) in younger individuals with an eGFR >60 mL/min/1.73 m2 and below the third percentile for their age/gender category. The use of third percentile eGFR rates as a cut-off based on age/gender-specific reference values of eGFR allows the detection of these false positives and negatives. In the present article, we focus on an important and frequently omitted criterion in epidemiological studies: chronicity. Indeed, the two most important factors introducing a high number (up to 50%) of false positives are lack of confirming proteinuria and the absence of proof of chronicity of the eGFR found at first screening. There is an urgent need for quality studies of the prevalence of CKD using representative randomized samples of the population, applying the KDIGO guidelines correctly.

Effects of Race and Sex on Measured GFR: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Kidney failure disproportionately affects older blacks versus whites. The reasons are unknown and may be related to lower measured glomerular filtration rate (GFR) and higher levels of albuminuria in community-based population samples.

STUDY DESIGN

Cross-sectional analysis of a substudy of a prospective cohort.

SETTING & PARTICIPANTS

Ancillary study following Multi-Ethnic Study of Atherosclerosis (MESA) visit 5.

PREDICTOR

Age, sex, and race.

OUTCOMES & MEASUREMENTS

Measured GFR using plasma clearance of iohexol and urine albumin-creatinine ratio (ACR).

RESULTS

GFR was measured in 294 participants. Mean age was 71±9 (SD) years, 47% were black, 48% were women, mean GFR was 73±19mL/min/1.73m², and median ACR was 10.0 (IQR, 5.8-20.9) mg/g. Measured GFR was on average 1.02 (95% CI, 0.79-1.24) mL/min/1.73m² lower per year older. Mean GFR indexed for body surface area was not different between blacks versus whites (mean difference, 2.94 [95% CI, -1.37 to 7.26] mL/min/1.73m²), but was lower in women than men (mean difference, -9.34 [95% CI, -13.53 to -5.15] mL/min/1.73m²); this difference persisted and remained significant after adjustment for demographics, clinical characteristics, and measures of body size. The difference between men and women, but not between blacks and whites, was substantially greater when GFR was not indexed for body surface area. ACR was higher in older versus younger participants (mean difference, 3.2% [95% CI, 1.5%-4.8%] per year), but geometric mean ratio of ACR did not differ between blacks versus whites (mean difference, 19.7%; 95% CI, -39.1% to 6.1%) or between men versus women (mean difference, -4.4%; 95% CI, -27.7% to 26.3%).

LIMITATIONS

This is a study of survivors. People who agreed to participate were younger than those who refused.

CONCLUSIONS

In this first community-based study that included blacks and whites, no differences in measured GFR between races were found, suggesting that other factors must account for the disproportionately higher burden of kidney failure in older blacks versus whites.

Chronic kidney disease, hypertension, diabetes, and obesity in the adult population of Morocco: how to avoid "over"- and "under"-diagnosis of CKD

The prevalence of hypertension, diabetes, obesity, and chronic kidney disease (CKD) in an adult Arabic-Berber population was investigated according to 2012 KDIGO guidelines. A stratified, randomized, representative sample of 10,524 participants was obtained. Weight, height, blood pressure, proteinuria (dipstick), plasma creatinine, estimated glomerular filtration rate, and fasting glycemia were measured. Abnormal results were controlled within 2 weeks; eGFR was retested at 3, 6, and 12 months. The population adjusted prevalences were 16.7% hypertension, 23.2% obesity, 13.8% glycemia, 1.6% for eGFR under 60 ml/min/1.73 m(2) and confirmed proteinuria 1.9% and hematuria 3.4%. Adjusted prevalence of CKD was 5.1%; distribution over KDIGO stages: CKD1: 17.8%; CKD2: 17.2%; CKD3: 52.5% (3A: 40.2%; 3B: 12.3%); CKD4: 4.4%; CKD5: 7.2%. An eGFR distribution within the sex and age categories was constructed using the third percentile as threshold for decreased eGFR. A single threshold (under 60 ml/min/1.73 m(2)) eGFR classifying CKD3-5 leads to "overdiagnosis" of CKD3A in the elderly, overt "underdiagnosis" in younger individuals with eGFR over 60 ml/min/1.73 m(2), below the third percentile, and no proteinuria. By using the KDIGO guidelines in a correct way, "kidney damage" (confirmed proteinuria, hematuria) and the demonstration of chronicity of decreased eGFR <60 ml/min/1.73 m(2), combined with the third percentile as a cutoff for the normality of eGFR for age and sex, overcome false positives and negatives, substantially decrease CKD3A prevalence, and greatly increase the accuracy of identifying CKD.

Maremar, prevalence of chronic kidney disease, how to avoid over-diagnosis and under-diagnosis

Chronic kidney disease is considered as a major public health problem. Recent studies mention a prevalence rate between 8%-12%. Several editorials, comments, short reviews described the weaknesses (lack of confirmation of proteinuria, and of chronicity of decreased estimated glomerular filtration rate) of a substantial number of studies and the irrational of using a single arbitrary set point, i.e. diagnosis of chronic kidney disease whenever the estimated glomerular filtration rate is less than 60mL/min/1.73m(2). Maremar (Maladies rénales chroniques au Maroc) is a prevalence study of chronic kidney disease, hypertension, diabetes and obesity in a randomized, representative, high response rate (85%), sample of the adult population of Morocco, strictly applying the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Compared to the vast majority of the available studies, Maremar has a low prevalence of chronic kidney disease (2.9% adjusted to the actual adult population of Morocco). The population pyramid, and particularly the confirmation of proteinuria and "chronicity" of the decreased estimated glomerular filtration rate are the main reasons for this low prevalence of chronic kidney disease. The choice of arbitrary single threshold of estimated glomerular filtration rate for classifying stage 3-5 chronic kidney disease inevitably leads to "over-diagnosis" (false positives) of the disease in the elderly, particularly those without proteinuria, hematuria or hypertension, and to "under-diagnosed" (false negatives) in younger individuals with an estimated glomerular filtration rate above 60mL/min/1.73m(2) and below the 3rd percentile of their age/gender category. There is an urgent need for quality studies using in a correct way the recent KDIGO guidelines when investigating the prevalence of chronic kidney disease, in order to avoid a 50 to 100% overestimation of a disease state with potential dramatic consequences. The combination of the general population screening encompassing four different major health problems in the same screening procedure, using the correct methodologies and procedures, combined with a prevention/follow-up program results in a clinically/scientifically relevant program.

An Age-Calibrated Definition of Chronic Kidney Disease: Rationale and Benefits

Defining chronic kidney disease (CKD) is the subject of intense debate in the current nephrology literature. The debate concerns the threshold value of estimated glomerular filtration rate (eGFR) used to make the diagnosis of CKD. Current recommendations argue that a universal threshold of 60 mL/min/1.73m(2) should be used. This threshold has been defended by epidemiological studies showing that the risk of mortality or end-stage renal disease increases with an eGFR below 60 mL/min/1.73m(2). However, a universal threshold does not take into account the physiologic decline in GFR with ageing nor does it account for the risk of mortality and end-stage renal disease being trivial with isolated eGFR levels just below 60 mL/min/1.73m(2) in older subjects and significantly increased with eGFR levels just above 60 mL/min/1.73m(2) among younger patients. Overestimation of the CKD prevalence in the elderly (medicalisation of senescence) and underestimation of CKD (potentially from treatable primary nephrologic diseases) in younger patients is of primary concern. An age-calibrated definition of CKD has been proposed to distinguish age-related from disease-related changes in eGFR. For patients younger than 40 years, CKD is defined by eGFR below 75 mL/min/1.73m(2). For patients with ages between 40 and 65 years, CKD is defined by 60 mL/min/1.73m(2). For subjects older than 65 years without albuminuria or proteinuria, CKD is defined by eGFR below 45 mL/min/1.73m(2).