National Kidney Foundation Laboratory Engagement Working Group Recommendations for Implementing the CKD-EPI 2021 Race-Free Equations for Estimated Glomerular Filtration Rate: Practical Guidance for Clinical Laboratories

Better Prediction of Clinical Outcome with Estimated Glomerular Filtration Rate by CKD-EPI 2021

BACKGROUND

While the real-world impact of estimated glomerular filtration rate (eGFR) equation change on clinical outcome in a longitudinal cohort setting is limited, external valuation of equation performance should be performed in different population cohorts. This study aimed to compare differential impacts of eGFR values, calculated by 5 equations in a Korean patient population, on clinical outcomes.

METHODS

This retrospective longitudinal follow-up cohort study analyzed 23 246 participants with standardized creatinine/cystatin C assay-based laboratory results. The primary exposure was baseline eGFR calculated by 5 different equations including the recently developed 2021 race-free Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations. Clinical outcomes including all-cause mortality, renal replacement therapy, and albuminuria were analyzed to estimate the hazard ratio of the eGFR on clinical outcomes.

RESULTS

Among the 5 equations, CKD-EPI 2021 with creatinine and cystatin C (CKD-EPI 2021-CrCys) showed an earlier increase in hazard ratios for all clinical outcomes, while CKD-EPI 2012 with cystatin C showed a higher hazard ratio for all-cause mortality at low eGFR. Replacing CKD-EPI 2012 with CKD-EPI 2021-CrCys, 5.4% of patients with mortality and 3.3% of patients who received renal replacement therapy were reclassified to a lower risk stage.

CONCLUSIONS

The 2021 CKD-EPI equations were acceptable in a Korean population, with better predictive power for clinical outcomes when compared to previous equations. The updated race-free factors for eGFR calculation improved identification of patients at risk for clinical outcomes.

Creatinine clearance/eGFR ratio: a simple index for muscle mass related to mortality in ICU patients

INTRODUCTION

In patients admitted to the intensive care unit (ICU), muscle mass is inversely associated with mortality. Although muscle mass can be estimated with 24-h urinary creatinine excretion (UCE), its use for risk prediction in individual patients is limited because age-, sex-, weight- and length-specific reference values for UCE are lacking. The ratio between measured creatinine clearance (mCC) and estimated glomerular filtration rate (eGFR) might circumvent this constraint. The main goal was to assess the association of the mCC/eGFR ratio in ICU patients with all-cause hospital and long-term mortality.

METHODS

The mCC/eGFR ratio was determined in patients admitted to our ICU between 2005 and 2021 with KDIGO acute kidney injury (AKI) stage 0-2 and an ICU stay ≥ 24 h. mCC was calculated from UCE and plasma creatinine and indexed to 1.73 m2. mCC/eGFR was analyzed by categorizing patients in mCC/eGFR quartiles and as continuous variable.

RESULTS

Seven thousand five hundred nine patients (mean age 61 ± 15 years; 38% female) were included. In-hospital mortality was 27% in the lowest mCC/eGFR quartile compared to 11% in the highest quartile (P < 0.001). Five-year post-hospital discharge actuarial mortality was 37% in the lowest mCC/eGFR quartile compared to 19% in the highest quartile (P < 0.001). mCC/eGFR ratio as continuous variable was independently associated with in-hospital mortality in multivariable logistic regression (odds ratio: 0.578 (95% CI: 0.465-0.719); P < 0.001). mCC/eGFR ratio as continuous variable was also significantly associated with 5-year post-hospital discharge mortality in Cox regression (hazard ratio: 0.27 (95% CI: 0.22-0.32); P < 0.001).

CONCLUSIONS

The mCC/eGFR ratio is associated with both in-hospital and long-term mortality and may be an easily available index of muscle mass in ICU patients.

Association between estimated glucose disposal rate and cardiovascular mortality across the spectrum of glucose tolerance in the US population

AIMS

To determine if estimated glucose disposal rate (eGDR) can predict cardiovascular disease mortality risk at different levels of glycaemic tolerance.

MATERIALS AND METHODS

The eGDR levels of 11 656 individuals aged 45-79 years from the National Health and Nutrition Examination Survey cycles 1999 to 2010 were analysed. Associations between eGDR levels and all-cause and cardiovascular mortality were examined using Cox proportional hazards and Fine and Gray models, respectively.

RESULTS

After a median follow-up of 12.8 years, a total of 2852 participants died, with 777 of those deaths attributed to cardiovascular causes. When comparing participants with eGDR values of ≤4 mg/kg/min to those with eGDR values falling within the ranges of 4-6, 6-8 and >8 mg/kg/min, it was found that the latter groups exhibited lower hazard ratios for both all-cause mortality (0.61 [0.52-0.72], 0.61 [0.52-0.72] and 0.46 [0.39-0.55]) and cardiovascular mortality (0.44 [0.33-0.57], 0.45 [0.34-0.59] and 0.30 [0.23-0.40]). A U-shaped relationship between eGDR and all-cause mortality was observed, with an inflection point at an eGDR of 9.54 mg/kg/min.

CONCLUSIONS

In the general population, the association between reduced eGDR and all-cause and cardiovascular mortality was independently significant, contributing to the identification of individuals at high risk for different levels of glucose tolerances.

Association between the lipid accumulation product and chronic kidney disease among adults in the United States

The objective of this research was to explore the potential association between lipid accumulation product (LAP) and chronic kidney disease (CKD) among adult population of United States (US). Using cross-sectional data from the 2013 to 2018 National Health and Nutrition Examination Survey (NHANES), we explored the association of LAP with CKD, low estimated glomerular filtration rate (eGFR), and albuminuria. This analysis encompassed multivariate logistic regression analyses, smoothed curve fitting, subgroup analyses, and interaction tests. We found a significant positive association between higher ln-transformed LAP (LAP was transformed using a natural logarithm) and the prevalence of CKD, low-eGFR and albuminuria. Notably, this association of ln-transformed LAP with CKD and albuminuria was significantly influenced by diabetes status and sex (P for interaction < 0.05), while no significant interaction was observed regarding the association with low-eGFR (P for interaction > 0.05). Additionally, in model 3 (adjusted for all included covariates except eGFR and urinary albumin-creatinine ratio (UACR)), a nonlinear relationship was identified between ln-transformed LAP and the presence of both CKD and albuminuria, with inflection points of 4.57 and 4.49, respectively. This indicates that this correlation is more pronounced on the right of the inflection point. In conclusion, the findings indicate a significant association between LAP and the prevalence of CKD in US adults.

Retinal and Choroidal Phenotypes Across Novel Subtypes of Type 2 Diabetes Mellitus

PURPOSE

To investigate longitudinal changes in choroidal thickness (CT) and ganglion cell-inner plexiform layer thickness (GC-IPLT) across distinct phenotypes of type 2 diabetes mellitus (T2DM) patients.

DESIGN

Prospective cohort study.

METHODS

T2DM patients were categorized into 5 groups (SAID, SIDD, SIRD, MOD, and MARD) using K-means clustering based on β-cell function and insulin resistance. Swept-source optical coherence tomography measured baseline and 4-year follow-up CT and GC-IPLT. Linear mixed-effects models assessed absolute and relative changes in CT and GC-IPLT across subtypes.

RESULTS

Over a median 4.11-year follow-up, CT and GC-IPLT decreased significantly across all groups. Choroidal thinning rates were most pronounced in SIDD (-6.5 ± 0.53 µm/year and -3.5 ± 0.24%/year) and SAID (-6.27 ± 0.8 µm/year and -3.19 ± 0.37%/year), while MARD showed the slowest thinning rates (-3.63 ± 0.34 µm/year and -1.98 ± 0.25%/year). SIRD exhibited the greatest GC-IPLT loss (-0.66 ± 0.05 µm/year and -0.91 ± 0.07%/year), with the least in SIDD (-0.36 ± 0.05 µm/year and -0.49 ± 0.07%/year), all statistically significant (all P < 0.001). Adjusted for confounding variables, SIDD and SAID groups showed faster CT thinning than MARD [-2.57 µm/year (95% CI: -4.16 to -0.97; P = 0.002) and -2.89 µm/year (95% CI: -4.12 to -1.66; P < 0.001), respectively]. GC-IPLT thinning was notably accelerated in SIRD versus MARD, but slowed in SIDD relative to MARD [differences of -0.16 µm/year (95% CI: -0.3 to -0.03; P = 0.015) and 0.15 µm/year (95% CI: 0.03 to 0.27; P = 0.015), respectively].

CONCLUSIONS

Microvascular damage in the choroid is associated with SIDD patients, whereas early signs of retinal neurodegeneration are evident in SIRD patients. All these changes may precede the onset of DR.

Efficacy and Safety in a Real-World Study of the New Oral Formulation of Semaglutide in Patients with Chronic Kidney Disease and Type 2 Diabetes Mellitus

Background/Objectives: GLP-1 receptor agonists (GLP-1RAs) have emerged as fundamental components in the treatment of type 2 diabetic patients (T2DM) with chronic kidney disease (CKD). The oral formulation represents a novel therapeutic tool but may affect drug efficacy. This study sought to compare the effectiveness of subcutaneous versus oral semaglutide formulations in patients with CKD. Methods: A retrospective study in a real-world setting compared type 2 diabetes and chronic kidney disease patients, initiating oral semaglutide treatment to a historically matched control group treated with subcutaneous semaglutide. The matching considered factors such as estimated glomerular filtration rate (eGFR), age, and sex. Results: Nineteen patients were included in both groups, with a mean age of 68.0. Seventy-two percent were males with a CKD-EPI eGFR of 49.9 mL/min/1.73 m2 and a median urine albumin-to-creatinine ratio of 12.7 mg/g. Of the study participants, 94% and 79% of patients were on the maximum semaglutide sbc vs. oral dose, while 5.3% and 15.8% were on the sbc vs. oral low dose. Oral semaglutide significantly reduced HbA1C and BMI, identical to the control group (-0.9 and -1.4, p > 0.05). Renal function parameters and blood pressure remained stable throughout the follow-up in both groups. The main side effect was digestive intolerance (affecting three patients in the oral group and two patients in the subcutaneous group, p = 0.6), although the treatment abandonment percentage was similar. Conclusions: The oral formulation of semaglutide demonstrated equivalent effectiveness in glucose control and body weight management in patients with T2DM and CKD, even with a higher proportion of patients receiving low to medium doses. Gastrointestinal side effects were comparable between both oral and subcutaneous formulations.

Effect of exercise-based rehabilitation on functional capacity and renal function in type 2 diabetes mellitus with nephropathy: a randomized controlled trial

INTRODUCTION

Diabetic nephropathy is a growing public health challenge with implications on health. Renal function decline impacts the functional ability and overall health and well-being of individuals with diabetic nephropathy due to development of several renal manifestations. The objective of the study was to determine the effect of an exercise-based rehabilitation program on functional capacity and renal function among individuals with type 2 diabetic nephropathy.

METHODS

A total of 283 individuals were screened and 60 eligible participants aged 45-70 years with diabetic nephropathy were randomly allocated (n = 30 each) to the intervention group (IG) and control group (CG), respectively. The study outcome measures comprised of functional capacity (6-min walk test) and renal function assessed at baseline, 12th week and 24th week. Participants allocated to IG received 12 weeks of exercise based rehabilitation (comprising of supervised + home-based exercises) along with standard care and followed-up till 24th week.

RESULTS

The repeated measures ANOVA with Greenhouse-Geisser correction indicated significant timepoint*group interaction effect for 6-min walk distance F (1.71, 90.59) = 619, p < 0.001, serum creatinine F (1.23, 65.14) = 174.8, p < 0.001, estimated glomerular filtration rate F (1.15, 60.88) = 105.2, p < 0.001, serum urea F (1.48, 78.45) = 261.4, p < 0.001 and urine protein F (1.13, 59.82) = 4.58, p < 0.328.

CONCLUSION

The study found that exercise based rehabilitation improved both functional capacity and renal function among individuals with type 2 diabetic nephropathy.

Chronic kidney disease in postmenopausal women is associated with tooth loss

OBJECTIVE

Menopause is characterized by changes in reproductive hormone levels that can negatively affect bone. Chronic kidney disease (CKD) and tooth loss are also important and common health issues after menopause. This study aimed to evaluate the association between CKD and tooth loss in postmenopausal women.

METHODS

The study evaluated 64,971 participants who participated in the Korean National Health and Nutrition Examination Survey (KNHANES) from 2010-2018, including postmenopausal women, aged 40 to 79 years. Participants were divided into two groups based on the number of teeth in their dentition (≥20 and <20).

MAIN OUTCOME MEASURES

The association between CKD and tooth loss was analyzed using multivariate logistic regression. Age, income, education, smoking, alcohol intake, body mass index, hypertension, diabetes, annual oral examination, toothbrushing, and the use of oral care products were considered. Subgroup analyses were further conducted according to age (40-65 yr and 66-79 yr).

RESULTS

After adjusting for covariates, CKD and estimated glomerular filtration rate were significantly associated with having ≥20 teeth (PT20; CKD: odds ratio [OR] 1.41, 95% confidence interval [CI] 1.04-1.90; estimated glomerular filtration rate (10 mL/min/1.73 m 2 ): OR 0.90, 95% CI 0.86-0.94). Importantly, the association between CKD and PT20 was significant in postmenopausal women, aged 66 to 79 years (OR 1.45, 95% CI 1.05-2.01).

CONCLUSIONS

In postmenopausal women, CKD and tooth loss may be associated. The association is significant in postmenopausal women, aged 66 to 79 years.

Evaluating Laboratory Communications to NKF-WG Recommended Stakeholders during Implementation of the CKD-EPI 2021 Equation

BACKGROUND

In 2022, the National Kidney Foundation's Laboratory Engagement Working Group (NKF-WG) released recommendations for clinical implementation of the race-free Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2021 estimated glomerular filtration rate (eGFR) equation.This study examined laboratory communications during CKD-EPI 2021 implementation including communication methods and delivery, content inclusion, and alignment with stakeholder inclusion as defined by the NKF-WG.

METHODS

An anonymous web-based survey was distributed to members of ADLM (AACC) and the American Society for Clinical Laboratory Science (ASCLS) in November 2022 to solicit laboratory directors of CLIA-licensed clinical laboratories in the United States. Seventeen questions covering topics related to implementation of CKD-EPI 2021, stakeholder inclusion, methods and timing of communications delivery, and content inclusion were surveyed.

RESULTS

All participating laboratories (n = 28) reported including physicians/advanced practitioners in implementation communications, while only 10.7% reported inclusion of patients. When reporting on methods of communication, 81.5% (n = 27) of respondents reported using multiple methods of communication with providers and 88.8% issued provider communications prior to implementation. In contrast, when patient communications were delivered, 87.5% (n = 8) issued these communications exclusively after CKD-EPI 2021 implementation and the majority (6 of 8) reported using only one method of communication during delivery. When reporting on content inclusion, 64.3% (n = 28) of laboratories reported including concerns regarding previous race-based eGFR equations in communications with physicians/advanced practitioners, while only 16.7% (n = 18) of those who included this information did so with patients.

CONCLUSIONS

Participants reported limited engagement in CKD-EPI 2021 laboratory-to-patient implementation communications as well as limited inclusion of additional stakeholder groups, as defined in the NKF-WG recommendations. Laboratories utilized multiple communication methods and deliveries in physician/advanced practitioner communications; however, this strategy was not replicated when engaging with additional NKF-WG stakeholder groups.

Prevalence of and factors associated with chronic kidney disease among patients infected with human immunodeficiency virus attending care and treatment centers at tertiary hospitals in dodoma, Tanzania

Background

The burden and risk of developing chronic kidney disease (CKD) among patients with Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS) is higher than in the general population. This study aimed to determine prevalence of and associated factors with CKD among adults infected with human immunodeficiency virus at tertiary hospitals in Dodoma, Tanzania.

Method

ology: A cross-sectional study was carried out between November 2022 to April 2023. Patients' demographic data, and clinical measurements were obtained on the day of the visit. Laboratory investigations were performed as standard of care. Descriptive and inferential analyses were performed, and variables associated with CKD were identified by multivariable logistic regression.

Results

A total of 223 patients were enrolled, with a median age of 47 (IQR 38-56) years, and 72.2 % were female. The CKD prevalence was 23.3 % whereby 18.4 % had CKD stage 3a, 4.5 % had CKD stage 3 b, and 0.4 % had CKD stage 4. CKD was observed largely among patients with obesity (34.15 %), anemia (29.41 %), hypertension (45.00 %), and diabetes mellitus (50.00 %). Variables with higher odds for CKD after adjusted analysis were hypertension (OR 3.03, 95 %% CI 1.29-7.11, P = 0.0109), diabetes mellitus (OR 4.50, 95 % CI 1.35-15.03, P = 0.0144), obesity (OR 3.07, 95 % CI 1.11-8.47, P = 0.0301), anaemia (OR 2.42, 95 % CI 1.12-5.26, P = 0.0252) and for each one-unit increase in age (years), there was statistically significant increase in the odds of having CKD by 1.084 folds (OR = 1.084, 95 % CI 1.039-1.131, p = 0.0002).

Conclusion

The prevalence of CKD among patients with HIV/AIDS is high. Age, obesity, anaemia, hypertension, and diabetes mellitus were strongly associated with CKD suggesting a need for integrating initiatives for non-communicable disease control in this population.

Performance of race-neutral eGFR equations in patients with decompensated cirrhosis

The 2021 Chronic Kidney Disease Epidemiology Collaboration equation [CKD-EPI 2021] is a race-neutral equation recently developed and rapidly implemented as a reference standard to estimate glomerular filtration rate(GFR). However, its role in cirrhosis has not been examined especially in low GFR. We analyzed the performance of CKD-EPI 2021 compared to other equations with protocol-measured GFR (mGFR) in cirrhosis. We analyzed 2090 unique adult patients with cirrhosis undergoing protocol GFR measurements using iothalamate clearance from 1985 to 2015 when listed for liver transplantation at Baylor University in Dallas and Fort Worth, Texas. Using mGFR as a reference standard, the CKD-EPI 2021 was compared to CKD-EPI 2012, Modification of Diet in Renal Disease-4, Modification of Diet in Renal Disease-6, Royal Free Hospital, and GFR Assessment in Liver disease overall and in certain subgroups (ascites, mGFR ≤ 30 mL/min/1.73 m 2 , diagnosis, Model for End-Stage Liver Disease and gender). We examined bias (difference between eGFR and mGFR), accuracy (p30: eGFR within ± 30% of mGFR) and agreement between eGFR and mGFR categories. CKD-EPI 2021 had the second lowest bias across the entire range of GFR after GFR Assessment in Liver disease (6.6 vs. 4.6 mL/min/1.73 m 2 , respectively, p < 0.001). The accuracy of CKD-EPI 2021 was similar to CKD-EPI 2012 (p30 = 67.8% vs. 67.9%, respectively) which was higher than the other equations ( p < 0.001). It had a similar performance in patients with ascites, by diagnoses, Model for End-Stage Liver Disease subgroups, by gender, and in non-Black patients. However, it had a relatively higher overestimation in mGFR ≤ 30 mL/min/1.73 m 2 than most equations (18.5 mL/min/1.73m 2 , p < 0.001). Specifically, 64% of patients with mGFR ≤ 30 mL/min/1.73m 2 were incorrectly classified as a less severe CKD stage by CKD-EPI 2021. In Blacks, CKD-EPI 2021 underestimated eGFR by 17.9 mL/min/1.73 m 2 , which was higher than the alternate equations except for Royal Free Hospital ( p < 0.001). The novel race-neutral eGFR equation, CKD-EPI 2021, improves the GFR estimation overall but may not accurately capture true kidney function in cirrhosis, specifically at low GFR. There is an urgent need for a race-neutral equation in liver disease reflecting the complexity of kidney function physiology unique to cirrhosis, given implications for organ allocation and dual organ transplant.

Dynamic natural components and morphological changes in nonculprit subclinical atherosclerosis in patients with acute coronary syndrome and mild chronic kidney disease at the 1-year follow-up and clinical significance at the 5-year follow-up

INTRODUCTION

The natural outcome of coronary plaque in acute coronary syndrome (ACS) patients with chronic kidney disease (CKD) is unique, which can be analyzed quantitatively by optical flow ratio (OFR) software.

METHODS

A total of 184 ACS patients with at least one nonculprit subclinical atherosclerosis (NSA) detected by optical coherence tomography (OCT) at baseline and 1-year follow-up were divided into non-CKD group (n = 106, estimated glomerular filtration rate (eGFR)> 90 mL/(min×1.73 m2)) and mild CKD group (n = 78, 60≤eGFR<90 mL/(min×1.73 m2)). Changes of normalized total atheroma volume (TAVn) of NSA was the primary endpoint at the 1-year follow-up.

RESULTS

Patients with mild CKD showed more TAVn progression of NSA than non-CKD (p = 0.019) from baseline to the 1-year follow-up, which was mainly due to an increase in calcium TAVn (p<0.001). The morphological change in the maximal calcification thickness (p = 0.026) was higher and the change in the distance from the calcified surface to the contralateral coronary media membrane (ΔC-to-M) at the maximal cross-sectional calcium area was lower (p<0.001) in mild CKD group than in non-CKD group. Mild CKD had more NSA related MACEs at the 5-year follow-up than non-CKD (30.8% vs. 5.8%, p = 0.045).

CONCLUSIONS

Mild CKD patients had more plaque progression of NSA which showed the increase of calcium component with more protrusion into the lumen morphologically at the 1-year follow-up and a higher corresponding incidence of NSA-related MACEs at the 5-year follow-up.

TRIAL REGISTRATION

Clinical Trial registration ClinicalTrials.gov. NCT02140801. https://classic.clinicaltrials.gov/ct2/show/NCT02140801.

Association of different domains of physical activity with diabetic kidney disease: a population-based study

Background

The aim of this cross-sectional study was to elucidate the associations between various domains of physical activity, such as occupation-related (OPA), transportation-related (TPA), leisure-time (LTPA) and overall physical activity (PA), and diabetic kidney disease.

Methods

Our study encompassed 2,633 participants, drawn from the cross-sectional surveys of the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2018, and employed survey-weighted logistic regression, generalized linear regression, and restricted cubic spline (RCS) analyses to ascertain the relationship between different domains of physical activity and diabetic kidney disease.

Results

After controlling for all confounders, multivariate logistic regression analyses revealed a lack of correlation between the various domains of physical activity and the prevalence of diabetic kidney disease. Multiple generalized linear regression analyses showed that durations of PA (β = 0.05, 95% CI, 0.01-0.09, P = 0.012) and TPA (β = 0.32, 95% CI, 0.10-0.55, P = 0.006) were positively associated with eGFR levels; and LTPA durations were inversely associated with UACR levels (β = -5.97, 95% CI, -10.50 - -1.44, P = 0.011). The RCS curves demonstrated a nonlinear relationship between PA, OPA, and eGFR, as well as a nonlinear correlation between PA and ACR. Subgroup and sensitivity analyses largely aligned with the outcomes of the multivariate generalized linear regression, underscoring the robustness of our findings.

Conclusion

Our population-based study explored the association between different domains of physical activity and diabetic kidney disease. Contrary to our expectations, we found no significant association between the duration of physical activity across all domains and the prevalence of diabetic nephropathy. Nonetheless, renal function markers, including eGFR and UACR, exhibited significant correlations with the duration of total physical activity (TPA) and leisure-time physical activity (LTPA), respectively, among diabetic patients. Interestingly, our findings suggest that diabetic patients engage in physical activity to preserve renal function, ensuring moderate exercise durations not exceeding 35 hours per week.

Clinical Impacts of Implementing the 2021 Race-Free Chronic Kidney Disease Epidemiology Collaboration Estimated Glomerular Filtration Rate

BACKGROUND

Estimated glomerular filtration rate (eGFR) has become incorporated into multiple clinical management situations. Historically, equations included a Black race coefficient, which lacked biological plausibility and created potential to exacerbate health disparities. A new equation created in 2021 changed the weighting of age, sex, and creatinine by modeling against a diverse cohort and removing the Black race coefficient.

CONTENT

A variety of clinical outcomes including kidney disease risk stratification, medication dosing, patient eligibility for clinical trials, and kidney donation are impacted by implementation of the new equation. Nearly 2 years after its initial publication, many studies have reported on observed analytical performance of the 2021 eGFR determined as diagnostic concordance and percentage of estimates within 30% of measured GFR. Additionally, the potential clinical impacts following adoption of the new eGFR among different patient populations has also been reported. Here we review these studies with a focus on assessing the data associated with the transition from 2009 to 2021 Chronic Kidney Disease Epidemiology Collaboration equations.

SUMMARY

The reported interindividual variation in eGFR performance is significantly larger than any potential benefit derived from race coefficients. Both the 2021 eGFR and the 2009 eGFR analytical performance fall short of the validation cohort performance in most cohorts. However, the 2021 analytical is similar or better than the 2009 eGFR in most cohorts. Implementing the 2021 eGFR will remove a systematic overestimation of kidney function among Black patients.

Identification and outcomes of KDIGO-defined chronic kidney disease in 1.4 million U.S. Veterans with heart failure

AIMS

According to the Kidney Disease: Improving Global Outcomes (KDIGO) guideline, the definition of chronic kidney disease (CKD) requires the presence of abnormal kidney structure or function for >3 months with implications for health. CKD in patients with heart failure (HF) has not been defined using this definition, and less is known about the true health implications of CKD in these patients. The objective of the current study was to identify patients with HF who met KDIGO criteria for CKD and examine their outcomes.

METHODS AND RESULTS

Of the 1 419 729 Veterans with HF not receiving kidney replacement therapy, 828 744 had data on ≥2 ambulatory serum creatinine >90 days apart. CKD was defined as estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m2 (n = 185 821) or urinary albumin-to-creatinine ratio (uACR) >30 mg/g (n = 32 730) present twice >3 months apart. Normal kidney function (NKF) was defined as eGFR ≥60 ml/min/1.73 m2, present for >3 months, without any uACR >30 mg/g (n = 365 963). Patients with eGFR <60 ml/min/1.73 m2 were categorized into four stages: 45-59 (n = 72 606), 30-44 (n = 74 812), 15-29 (n = 32 077), and <15 (n = 6326) ml/min/1.73 m2. Five-year all-cause mortality occurred in 40.4%, 57.8%, 65.6%, 73.3%, 69.7%, and 47.5% of patients with NKF, four eGFR stages, and uACR >30mg/g (albuminuria), respectively. Compared with NKF, hazard ratios (HR) (95% confidence intervals [CI]) for all-cause mortality associated with the four eGFR stages and albuminuria were 1.63 (1.62-1.65), 2.00 (1.98-2.02), 2.49 (2.45-2.52), 2.28 (2.21-2.35), and 1.22 (1.20-1.24), respectively. Respective age-adjusted HRs (95% CIs) were 1.13 (1.12-1.14), 1.36 (1.34-1.37), 1.87 (1.84-1.89), 2.24 (2.18-2.31) and 1.19 (1.17-1.21), and multivariable-adjusted HRs (95% CIs) were 1.11 (1.10-1.12), 1.24 (1.22-1.25), 1.46 (1.43-1.48), 1.42 (1.38-1.47), and 1.13 (1.11-1.16). Similar patterns were observed for associations with hospitalizations.

CONCLUSION

Data needed to define CKD using KDIGO criteria were available in six out of ten patients, and CKD could be defined in seven out of ten patients with data. HF patients with KDIGO-defined CKD had higher risks for poor outcomes, most of which was not explained by abnormal kidney structure or function. Future studies need to examine whether CKD defined using a single eGFR is characteristically and prognostically different from CKD defined using KDIGO criteria.

L-shaped association between lean body mass to visceral fat mass ratio with hyperuricemia: a cross-sectional study

BACKGROUND

Insufficient attention has been given to examining the correlation between body composition and hyperuricemia, leading to inconsistent findings. The primary objective of this research is to explore the association between lean body mass index (LMI), visceral fat mass index (VFMI), and hyperuricemia. A specific emphasis will be placed on assessing the link between the ratio of lean body mass to visceral fat mass (LMI/VFMI) and hyperuricemia.

METHODS

The present study employed a cross-sectional design and involved a total of 9,646 individuals who participated in the National Health and Nutrition Examination Survey (NHANES). To explore the associations among the variables, logistic and linear regressions were employed. Additionally, subgroup analyses and sensitivity analyses were conducted based on various characteristics.

RESULTS

The results showed that LMI was positively associated with hyperuricemia (for Per-SD: OR = 1.88, 95%CI: 1.75, 2.01; for quartiles [Q4:Q1]: OR = 5.37, 95%CI: 4.31, 6.69). Meanwhile, VFMI showed a positive association with hyperuricemia (for Per-SD: OR = 2.02, 95%CI: 1.88, 2.16; for quartiles [Q4:Q1]: OR =8.37, 95%CI: 6.70, 10.47). When considering the effects of In LMI/VFMI, an L-shaped negative association with hyperuricemia was observed (for Per-SD: OR = 0.45, 95%CI: 0.42, 0.49; for quartiles [Q4:Q1]: OR = 0.16, 95%CI: 0.13, 0.20). Subgroup and sensitivity analyses demonstrated the robustness of this association across different subgroups. Additionally, the segmented regression analysis indicated a saturation effect of 5.64 for the In LMI/VFMI with hyperuricemia (OR = 0.20, 95%CI: 0.17, 0.24). For every 2.72-fold increase of In LMI/VFMI, the risk of hyperuricemia was reduced by 80%.

CONCLUSION

The LMI/VFMI ratio is non-linearly associated with serum uric acid. Whether this association is causal needs to be confirmed in further longitudinal studies or Mendelian randomization.

Application of the European Kidney Function Consortium Equation to Estimate Glomerular Filtration Rate: A Comparison Study of the CKiD and CKD-EPI Equations Using the Korea National Health and Nutrition Examination Survey (KNHANES 2008-2021)

Background and Objectives: The European Kidney Function Consortium (EKFC) equation has been newly proposed for estimating glomerular filtration rate (eGFR) across the spectrum of age. We compared the EKFC equation with the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations in a large-scale Korean population. Materials and Methods: Using the representative Korean health examination data, the Korea National Health and Nutrition Examination Survey (KNHANES 2008-2021), the records of 91,928 subjects (including 9917 children) were analyzed. We compared the EKFC equation with CKiD, CKD-EPI 2009, and CKD-EPI 2021 equations and investigated their agreement across GFR categories. Results: In the total population, the CKD-EPI 2021 equation yielded the highest eGFR value, followed by the CKD-EPI 2009 and EKFC equations. In children, the distribution of eGFR differed significantly between the EKFC and CKiD equations (p < 0.001), with a wider range of eGFR values found with the CKiD equation. Each equation showed weak or moderate agreement on the frequency of the GFR category (κ = 0.54 between EKFC and CKD-EPI 2021; κ = 0.77 between EKFC and CKD-EPI 2009). The eGFR values found by the EKFC equation showed high or very high correlations with those by the CKiD, CKD-EPI 2009, and CKD-EPI 2021 equations (r = 0.85, 0.97, and 0.97, respectively). As eGFR values increased, bigger differences were observed between equations. Conclusions: This large-scale study demonstrates that the EKFC equation would be applicable across the entire age spectrum in Asian populations. It also underscores that national kidney health would be highly affected by an eGFR equation being implemented. Additional investigation and more caution would be warranted for the transition of eGFR equations.

Renal relapse in children and adolescents with childhood-onset lupus nephritis: a 20-year study

OBJECTIVES

There is little data on renal relapse in childhood-onset LN (cLN). We investigate the incidence, predictive factors and outcomes related to renal relapse.

METHODS

We conducted a retrospective cohort study of all cLN diagnosed at ≤18 years between 2001-2021 to investigate the incidence and outcomes related to renal relapse.

RESULTS

Ninety-five Chinese cLN patients (91% proliferative LN) were included. Induction immunosuppression was prednisolone and CYC [n = 36 (38%)] or MMF [n = 33 (35%)]. Maintenance immunosuppression was prednisolone and MMF [n = 53 (54%)] or AZA [n = 29 (31%)]. The rates of complete remission/partial remission (CR/PR) at 12 months were 78.9%/7.4%. Seventy renal relapses occurred in 39 patients over a follow-up of 10.2 years (s.d. 5.9) (0.07 episode/patient-year). Relapse-free survival was 94.7, 86.0, 80.1, 71.2, 68.3, 50.3 and 44.5% at 1, 2, 3, 4, 5, 10 and 20 years, respectively. Multivariate analysis showed that LN diagnosis <13.1 years [adjusted hazard ratio (HRadj) 2.59 995% CI 1.27, 5.29), P = 0.01], AZA maintenance [HRadj 2.20 (95% CI 1.01, 4.79), P = 0.05], PR [HRadj 3.9 (95% CI 1.03, 9.19), P = 0.01] and non-remission [HRadj 3.08 (95% CI 1.35, 11.3), P = 0.04] at 12 months were predictive of renal relapse. Renal relapse was significantly associated with advanced chronic kidney disease (stages 3-5) and end-stage kidney disease (17.9% vs 1.8%, P < 0.01). Furthermore, patients with renal relapse showed an increased incidence of infections (30.8% vs 10.7%, P = 0.02), osteopenia (38.5% vs 17.9%, P = 0.04) and hypertension (30.8% vs 7.1%, P < 0.01).

CONCLUSION

Renal relapse is common among cLN, especially among young patients, and is associated with an increased incidence of morbidity and mortality. Attaining CR and the use of MMF appear to decrease the incidence of renal relapse.

Triglyceride-Glucose Index and Its Correlates: Associations with Serum Creatinine and Estimated Glomerular Filtration Rate in a Cross-Sectional Study from CHARLS 2011-2015

Background: Chronic kidney disease (CKD) has emerged as a significant global public health challenge, and the estimated glomerular filtration rate (eGFR) is widely used due to its convenience, low cost, and broad clinical applicability. Concurrently, insulin resistance (IR) serves as a crucial marker of metabolic disturbance, and alternative indicators have garnered increasing attention in CKD research in recent years. Objective: This study aims to investigate the relationship between IR-related indices (TyG index, TyG-BMI index, and TyG-WC index) and serum creatinine levels, as well as the eGFR, with the intention of uncovering their potential roles in the assessment of renal function. Methods: We analyzed nationally representative cross-sectional data from a cohort of individuals aged 45 and above in China, comprising 11,608 participants. Participants were categorized into different groups based on quartiles of the TyG index, and multiple factors, including gender, age, lifestyle, and co-morbidities, were adjusted for using linear regression models. Results: By linear regression, TyG, TyG-BMI, and TyG-WC indices were significantly positively correlated with serum creatinine and significantly negatively correlated with eGFR. Results showed similar trends when TyG, TyG-BMI, and TyG-WC indices were used as categorical variables. In the fully adjusted model, the highest quartile of serum creatinine was higher than the first quartile for TyG, TyG-BMI, and TyG-WC indices, with β values of 2.673, 3.67, and 1.937 mg/dL, respectively; the highest quartile of eGFR was lower than the first quartile, with β values of -2.4, -2.955, and -1.823 mL/min/1.73 m2. P values were statistically significant. Conclusions: This study indicates a consistent correlation between the TyG index and its related indices with serum creatinine levels and eGFR among the middle aged and elderly population in China. These findings suggest the potential utility of these indices in early screening and management of the risk of chronic kidney disease.

Bias and Accuracy of Glomerular Filtration Rate Estimating Equations in the US: A Systematic Review and Meta-Analysis

Importance

There is increasing concern that continued use of a glomerular filtration rate (GFR) estimating equation adjusted for a single racial group could exacerbate chronic kidney disease-related disparities and inequalities.

Objective

To assess the performance of GFR estimating equations across varied patient populations.

Data Sources

PubMed, Embase, Web of Science, ClinicalTrials.gov, and Scopus databases were systematically searched from January 2012 to February 2023.

Study Selection

Inclusion criteria were studies that compared measured GFR with estimated GFR in adults using established reference standards and methods. A total of 6663 studies were initially identified for screening and review.

Data Extraction and Synthesis

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, 2 authors independently extracted data on studies that examined the bias and accuracy of GFR estimating equations. For each outcome, a random-effects model was used to calculate pooled estimates. Data analysis was conducted from March to December 2023.

Main Outcomes and Measures

The primary outcomes were bias and accuracy of estimated GFRs in Black vs non-Black patients, as well as in individuals with chronic conditions. Bias was defined as the median difference between the measured GFR and the estimated GFR. Accuracy was assessed with P30 (the proportion of persons in a data set whose estimated GFR values were within 30% of measured GFR values) and measures of heterogeneity.

Results

A total of 12 studies with a combined 44 721 patients were included. Significant heterogeneity was found in the bias of various GFR estimation equations. Race-corrected equations and creatinine-based equations tended to overestimate GFR in Black populations and showed mixed results in non-Black populations. For creatinine-based equations, the mean bias in subgroup analysis was 2.1 mL/min/1.73 m2 (95% CI, -0.2 mL/min/1.73 m2 to 4.4 mL/min/1.73 m2) in Black persons and 1.3 mL/min/1.73 m2 (95% CI, 0.0 mL/min/1.73 m2 to 2.5 mL/min/1.73 m2) in non-Black persons. Equations using only cystatin C had small biases. Regarding accuracy, heterogeneity was high in both groups. The overall P30 was 84.5% in Black persons and 87.8% in non-Black persons. Creatinine-based equations were more accurate in non-Black persons than in Black persons. For creatinine-cystatin C equations, the P30 was higher in non-Black persons. There was no significant P30 difference in cystatin C-only equations between the 2 groups. In patients with chronic conditions, P30 values were generally less than 85%, and the biases varied widely.

Conclusions and Relevance

This systematic review and meta-analysis of GFR estimating equations suggests that there is bias in race-based GFR estimating equations, which exacerbates kidney disease disparities. Development of a GFR equation independent of race is a crucial starting point, but not the sole solution. Addressing the disproportionate burden of kidney failure on Black individuals in the US requires an enduring, multifaceted approach that should include improving diagnostics, tackling social determinants of health, confronting systemic racism, and using effective disease prevention and management strategies.

Exploring Renal Function Assessment: Creatinine, Cystatin C, and Estimated Glomerular Filtration Rate Focused on the European Kidney Function Consortium Equation

Serum creatinine and serum cystatin C are the most widely used renal biomarkers for calculating the estimated glomerular filtration rate (eGFR), which is used to estimate the severity of kidney damage. In this review, we present the basic characteristics of these biomarkers, their advantages and disadvantages, some basic history, and current laboratory measurement practices with state-of-the-art methodology. Their clinical utility is described in terms of normal reference intervals, graphically presented with age-dependent reference intervals, and their use in eGFR equations.

Performance of the European Kidney Function Consortium (EKFC) creatinine-based equation in United States cohorts

Estimating glomerular filtration rate (GFR) is important in daily practice to assess kidney function and adapting the best clinical care of patients with and without chronic kidney disease. The new creatinine-based European Kidney Function Consortium (EKFC) equation is used to estimate GFR. This equation was developed and validated mainly in European individuals and based on a rescaled creatinine, with the rescaling factor (Q-value) defined as the median normal value of serum creatinine in a given population. The validation was limited in Non-Black Americans and absent in Black Americans. Here, our cross-sectional analysis included 12,854 participants from nine studies encompassing large numbers of both non-Black and Black Americans with measured GFR by clearance of an exogenous marker (reference method), serum creatinine, age, sex, and self-reported race available. Two strategies were considered with population-specific Q-values in Black and non-Black men and women (EKFCPS) or a race-free Q-value (EKFCRF). In the whole population, only the EKFCPS equation showed no statistical median bias (0.14, 95% confidence interval [-0.07; 0.35] mL/min/1.73m2), and the bias for the EKFCRF (0.74, [0.51; 0.94] mL/min/1.73m2) was closer to zero than that for the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI2021) equation (1.22, [0.99; 1.47]) mL/min/1.73m2]. The percentage of estimated GFR within 30% of measured GFR was similar for CKD-EPI2021 (79.2% [78.5%; 79.9%]) and EKFCRF (80.1% [79.4%; 80.7%]), but improved for the EKFCPS equation (81.1% [80.5%; 81.8%]). Thus, our EKFC equations can be used to estimate GFR in the United States incorporating either self-reported race or unknown race at the patient's discretion per hospital registration records.

Biomedical Evaluation of Early Chronic Kidney Disease in the Air Force: Building a Predictive Model from the Taiwan Military Health Service

OBJECTIVE

Chronic kidney disease (CKD) is one of the most common diseases worldwide. The increasing prevalence and incidence of CKD have contributed to the critical problem of high medical costs. Due to stressful environments, aircrew members may have a high risk of renal dysfunction. A better strategy to prevent CKD progression in Air Force personnel would be to diagnosis CKD at an early stage. Since few studies have been conducted in Taiwan to examine the long-term trends in early CKD in Air Force aircrew members, this study is highly important. We investigated the prevalence of CKD and established a predictive model of disease variation among aircrew members.

MATERIALS AND METHODS

In this retrospective study, we included all subjects who had received physical examinations at a military hospital from 2004 to 2010 and who could be tracked for four years. The Abbreviated Modification of Diet in Renal Disease Formula (aMDRD) was used to estimate the glomerular filtration rate (GFR) and was combined with the National Kidney Foundation/ Kidney Disease Outcomes Quality Initiative (NKF-K/DOQI) to identify CKD patients.

RESULTS

A total of 212 aircrew members were assessed. The results showed that the prevalence of CKD was 3.8%, 9.4%, 9.0%, and 9.4% in each of the four years. According to the logistic regression analysis, abnormal urobilinogen levels, ketones, and white blood cell (WBC) counts in urine and a positive urine occult blood test increased the risk of CKD. A positive urine occult blood test can be used to predict the future risk of CKD. Moreover, the generalized estimating equation (GEE) model showed that a greater risk of CKD with increased examination time, age and seniority had a negative effect. In conclusion, abnormal urobilinogen levels, ketones, and urine WBC counts in urine as well as a positive urine occult blood test might serve as independent predictors for CKD.

CONCLUSION

In the future, we can focus not only on annual physical examinations but also on simple and accurate examinations, such as urine occult blood testing, to determine the risk of CKD and prevent its progression in our aircrew members.

Associations of urinary zinc exposure with blood lipid profiles and dyslipidemia: Mediating effect of serum uric acid

The relationship between zinc (Zn) exposure and abnormal blood lipids including dyslipidemia is contentious. Serum uric acid (SUA) has been reported to be correlated to both Zn exposure and dyslipidemia. The underlying mechanisms of Zn exposure associated with blood lipids and the mediating effects of SUA remain unclear. Therefore, this study analyzed the data from Chinese 2110 adults (mean age: 59.0 years old) in rural areas across China to explore the associations of Zn exposure with blood lipid profiles and dyslipidemia, and to further estimate the mediating effects of SUA in these relationships. The study data showed that urinary Zn was associated with increased levels of blood lipid components triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C). Moreover, an increased risk of dyslipidemia was observed in the study participants who had higher urinary Zn levels. Compared with the first quartile, the fourth quartile of urinary Zn concentration corresponded to the increase of TG (β = 0.20, 95 % CI: 0.12, 0.28), LDL-C (β = 0.06, 95 % CI: 0.01, 0.10) and dyslipidemia risk (OR = 2.16, 95 % CI: 1.50, 3.10), respectively. Elevated urinary Zn was also associated with higher levels of SUA and hyperuricemia risk. The SUA levels were positively related to total cholesterol (TC), TG, LDL-C levels and dyslipidemia risk. Mediation analyses revealed that SUA mediated 31.75 %, 46.16 % and 19.25 % of the associations of urinary Zn with TG, LDL-C levels and dyslipidemia risk, respectively. The subgroup and sensitivity analyses confirmed the positive associations between urinary Zn and blood lipid profiles and the mediating effect of SUA. The national population-based study further enhanced our understanding of the associations between Zn exposure and blood lipid profiles and mediating effect of SUA among generally healthy, middle-aged, and elderly individuals.

Exploring the health-related decision-making experiences of people with chronic kidney disease and their caregivers: A qualitative study

BACKGROUND

This study aimed to explore the decision-making experience of patients with chronic kidney disease (CKD) and their caregivers.

METHODS

This was a qualitative descriptive study of the decision-making experiences of individuals with stage 3-end-stage CKD and their family caregivers. One-on-one, semistructured interviews were conducted using a guide developed and approved by a community advisory group. Data were analyzed using thematic analysis.

RESULTS

Three themes were identified: (1) decisions triggered by declining health and broad in scope, (2) challenges to decision-making and (3) factors influencing decision-making. Participants' experiences with health-related decision-making demonstrated that decisions were triggered when health declined. Yet, decisions that impact disease progression were being made in stage 3. Decision-making was made difficult due to lack of information, complex co-morbidities, and poor resource utilization. However, the structure and nature of the medical appointment, supportive caregivers, and resources served to remove challenges.

CONCLUSION

Decision-support interventions must train patients and caregivers to be empowered participants in answer-seeking behaviours upstream of advanced illness.

PUBLIC CONTRIBUTIONS

This work was conducted in full collaboration with a community advisory board consisting of patients with CKD, caregivers and clinicians. These members are noted in the acknowledgement section, and those who worked with the team to develop the interview guide, study protocols, and manuscript preparation are included as authors. As part of their role, advisory members met monthly, providing input on recruitment, study progress, inclusion of diverse voices and added relevance to study findings.

Kidney Function and Physical Performance Decline: The Brain in Kidney Disease (BRINK) Cohort Study

Rationale & Objective

Patients with kidney failure have poor physical performance, but its trajectory is less clear. We examined physical function over the course of kidney disease, including the transition to dialysis.

Study Design

Observational cohort.

Setting & Participants

Community-dwelling adults aged ≥45 years in the Brain in Kidney Disease (BRINK) cohort study.

Predictors

Estimated glomerular filtration rate (eGFR) and urine albumin to creatinine ratio (UACR).

Outcomes

Change in physical performance using the Short Physical Performance Battery (SPPB) (primary) and gait speed (secondary).

Analytical Approach

Linear mixed effects regression models.

Results

The analytical cohort included 562 participants with mean age of 69.3 (SD, 9.8) years followed for up to 63 months. In total, 49.8% were women. In addition, 79.9% self-identified as White, and 15.3% self-identified as Black. In total, 48.8% had diabetes. Mean eGFR at baseline was 48.1 (SD, 24.3) mL/min/1.73 m2. In unadjusted analysis, lower eGFR was associated with greater decline in SPPB score (P trend < 0.001). The decline in SPPB score was larger among participants with lower eGFR, with a gradient from -0.15 (95% CI, -0.23 to -0.07) points per year for participants with eGFR ≥60 mL/min/1.73 m2 to -0.56 (95% CI, -0.84 to -0.27) for participants with eGFR <15 mL/min/1.73 m2 and -0.61 (95% CI, -0.90 to -0.33) after dialysis initiation. In covariate-adjusted models, SPPB did not continue to decline after dialysis initiation. In secondary analyses evaluating change in gait speed, gait speed continued to decline after dialysis initiation. Higher UACR was also associated with a greater decline in SPPB score and gait speed in unadjusted and adjusted models.

Limitations

Small number of participants started dialysis.

Conclusions

We found a graded association of chronic kidney disease stage and albuminuria with decline in physical performance. The decline in SPPB was not accelerated after dialysis initiation in covariate-adjusted models, whereas gait speed continued to decline.

Coffee consumption affects kidney function based on GCKR polymorphism in a Korean population

Kidney function can be preserved through pharmacological interventions and nonpharmacological strategies, such as lifestyle and dietary adjustments. Among these, coffee has been linked to protective effects on kidney function. However, few studies have investigated the effect of coffee consumption on kidney function according to specific genes. We hypothesized that the impact of coffee consumption on kidney function might vary depending on GCKR polymorphism. GCKR rs1260326 polymorphism was examined using the Korean genome and epidemiology data from 656 chronic kidney disease (CKD) cases and 38,540 individuals without CKD (non-CKD). GCKR polymorphism has been previously associated with both coffee consumption and kidney function in Europeans. We replicated the associations between GCKR rs1260326 and coffee consumption and kidney function in Korean individuals. We also explored the effect of coffee consumption on kidney function by multivariate logistic regression analysis. Individuals with the rs1260326 (TC/CC) genotype did not experience significant changes in CKD risk based on their coffee consumption habits. In contrast, individuals with the TT genotype exhibited a significantly lower risk of CKD based on coffee consumption. Interestingly, in the non-CKD group, a beneficial effect on estimated glomerular filtration rate was observed in individuals with the T allele as coffee consumption increased. Our findings supported the hypothesis and revealed that the impact of coffee consumption habits on kidney function may vary based on the GCKR rs1260326 genotype of Korean individuals.

Changes in Glomerular Filtration Rate After Switching From Tenofovir Disoproxil Fumarate to Tenofovir Alafenamide Fumarate for Human Immunodeficiency Virus Preexposure Prophylaxis

Background

Tenofovir alafenamide fumarate (TAF) was promoted as a safer alternative to tenofovir disoproxil fumarate (TDF) for human immunodeficiency virus oral preexposure prophylaxis (PrEP). It is unknown if switching from TDF to TAF translates to improved renal function. We used electronic health record (EHR) data to assess changes in creatinine-estimated glomerular filtration rate (eGFR) after switching from TDF to TAF.

Methods

We conducted a retrospective cohort study using EHR data from Kaiser Permanente Southern California. We identified individuals who switched from TDF to TAF between October 2019 and May 2022 and used time-varying propensity score matching to identify controls who were on TDF ("nonswitchers"). We then used Bayesian longitudinal modeling to compare differences in eGFR between switching and nonswitching scenarios.

Results

Among 5246 eligible individuals, we included 118 TDF to TAF switchers and 114 nonswitchers. Compared to nonswitchers, switchers had older age of starting TDF but similar body weights at index date. A higher proportion of switchers were White, on Medicare or Medicaid, and had dyslipidemia at index date. Switching to TAF was associated with a higher eGFR compared to staying on TDF in 3-15 months post-switch, but the differences were not statistically significant (eg, month 9 difference: 1.27 [95% credible interval, -1.35 to 3.89]). While most of the estimated changes showed eGFR increase associated with switching, most were <2 eGFR units. Sensitivity analyses to address missingness or nonadherence showed similar results.

Conclusions

Switching from TDF to TAF for PrEP was associated with a nonsignificant increase in eGFR. Findings need to be confirmed using larger cohorts.

Screening, identifying, and treating chronic kidney disease: why, who, when, how, and what?

1 in 7 American adults have chronic kidney disease (CKD); a disease that increases risk for CKD progression, cardiovascular events, and mortality. Currently, the US Preventative Services Task Force does not have a screening recommendation, though evidence suggests that screening can prevent progression and is cost-effective. Populations at risk for CKD, such as those with hypertension, diabetes, and age greater than 50 years should be targeted for screening. CKD is diagnosed and risk stratified with estimated glomerular filtration rate utilizing serum creatinine and measuring urine albumin-to-creatinine ratio. Once identified, CKD is staged according to C-G-A classification, and managed with lifestyle modification, interdisciplinary care and the recently expanding repertoire of pharmacotherapy which includes angiotensin converting enzyme inhibitors or angiotensin-II receptor blockers, sodium-glucose-cotransporter-2 inhibitors, and mineralocorticorticoid receptor antagonists. In this paper, we present the why, who, when, how, and what of CKD screening.

Factors Associated with Worsening Interstitial Fibrosis/Tubular Atrophy in Lupus Nephritis Patients Undergoing Repeat Kidney Biopsy

Background

Lupus nephritis (LN) is one of the most severe manifestations of systemic lupus erythematosus (SLE). Interstitial fibrosis/tubular atrophy (IFTA) on kidney biopsies strongly predicts progression to end-stage renal disease. However, factors associated with progression of IFTA are not known. The objective of this study was to evaluate the demographic, clinical, and histopathological factors at the time of index kidney biopsies that are associated with worsening IFTA on repeat biopsies.

Methods

Patients with LN Class I to V or mixed LN on index biopsies who underwent a clinically indicated repeat biopsy between 2004 and 2020 were identified. None-mild IFTA was defined as < 25% acreage of the interstitium affected by fibrosis and atrophy, and moderate-severe IFTA was defined as ≥ 25% of the interstitium affected. Patients with none-mild IFTA on index biopsies who progressed to moderate-severe IFTA on repeat biopsies were defined as progressors. Patients with none-mild IFTA on both biopsies were defined as non-progressors.

Results

Seventy-two patients who underwent clinically indicated repeat kidney biopsies were included, and 35 (49%) were identified as progressors. Compared to non-progressors, progressors had a higher proportion of proliferative LN (20 [57%] vs. 6 [17%], p = 0.002) and crescents (9 [26%] vs. 3 [8%], p = 0.045) on index biopsies. There was no difference regarding the time to repeat biopsy or the baseline characteristics, including eGFR, presence of hypertension and diabetes, urine protein to creatinine ratio, or the initial treatments.

Conclusions

Proliferative LN and the presence of crescents on index biopsies were associated with subsequent IFTA progression on repeat biopsies. This association indicates that glomerular damage is one of the major drivers of tubulointerstitial scarring in SLE. IFTA progression may, in turn, be the driving factor of poor treatment response and progression to chronic kidney disease.

Oxidative Balance Score and New-Onset Type 2 Diabetes Mellitus in Korean Adults without Non-Alcoholic Fatty Liver Disease: Korean Genome and Epidemiology Study-Health Examinees (KoGES-HEXA) Cohort

The oxidative balance score (OBS) is a novel composite of pro- and anti-oxidative markers for assessing the risk of cardiometabolic diseases and non-alcoholic fatty liver disease (NAFLD). However, it has not yet been established whether the OBS is related to type 2 diabetes mellitus (T2DM), especially in a population without NALFD. Therefore, we aimed to investigate the longitudinal effect of the OBS on T2DM in a large cohort of Korean adults without NALFD. Data were assessed from 9798 participants without NALFD from the Korean Genome and Epidemiology Study-Health Examinees (KoGES-HEXA) cohort. The participants were divided into three groups according to OBS tertiles, identified as T1-T3. We prospectively assessed the hazard ratios (HRs) with 95% confidence intervals (CIs) for new-onset T2DM using multivariable Cox proportional hazard regression models over 6 years following the baseline survey. During the mean 3.5 years of follow-up, 145 individuals (1.48%; 56 men and 89 women) developed T2DM. The HRs of T2DM for the OBS tertiles were 0.79 (95% CI, 0.53-1.18) and 0.60 (95% CI, 0.39-0.93) in the T2 and T3 groups after adjusting for metabolic parameters in subjects without NALFD, respectively; however, the T2 group did not show statistical significance toward a decrease in incident T2DM. A low OBS may be a useful predictive marker in new-onset T2DM for middle-aged and older subjects without NALFD. This implies that the OBS could be an additional valuable tool for assessing the incidence of T2DM among individuals without NAFLD.

The 2021 Chronic Kidney Disease Epidemiology Collaboration Race-Free Estimated Glomerular Filtration Rate Equations in Kidney Disease: Leading the Way in Ending Disparities

Purpose

In 2020, the National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) convened a Task Force to recommend an evidence-based race-free approach to estimated glomerular filtration rate (eGFR). After the rigorous review of more than 20 approaches, the NKF/ASN Task Force published the final report that recommended the implementation of the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI 2021) equation for eGFR using creatine and expanded utilization of cystatin C testing. The purpose of this manuscript is to provide a comprehensive overview of the evolution of eGFR equations, and an overview of the Task Force deliberations and recommendations. For over two decades, the equation recommended to calculate eGFR included a race coefficient to adjust for data that suggested that American adults with African ancestry had consistently higher serum creatinine levels.

Methods

We will provide a discussion illustrating why the 2021 CKD EPI equations are the most equitable solution to eGFR. We will also provide an overview of the current implementation status and best practices for the new equations. Lastly, we will discuss how deployment of the new equations is an important step toward eliminating significant disparities in CKD care which disproportionately affect communities of color.

Results

Removing race from the algorithm used to assess kidney function is most equitable. Since race is a social construct, its use in clinical algorithms has facilitated health disparities in Black/African American people, Hispanic/Latino people, and other racial and ethnic minority groups-those who are already disproportionately impacted by diabetes, hypertension, and kidney disease. In turn, these same individuals experience significant inequities in kidney health care including reduced access to nephrology care, home dialysis, and kidney transplant.

Conclusions

Adoption of the race-free 2021 CKD-EPI eGFR equations will have life changing implications for kidney health. It will aid in appropriate referral, identification, diagnosis, treatment, and management of kidney disease and transplantation services/options. The outcomes of widespread implementation of the new equations coupled with system change quality improvement interventions such as the kidney profile will lead to more equitable outcomes and begin to address the crippling disparities in early, appropriate testing for CKD.

11. Chronic Kidney Disease and Risk Management: Standards of Care in Diabetes-2024

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, an interprofessional expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Evaluation of the CKD-EPI 2021 creatinine equation using laboratory data: Considerations for practice changes among clinical laboratories in British Columbia, Canada

INTRODUCTION

Clinical laboratories in British Columbia, Canada implemented the CKD-EPI 2009 equation without the race variable for estimated glomerular filtration rate (eGFR) reporting since 2014. As more clinical laboratories adopt the new CKD-EPI 2021 equation, the study aims to compare these two race-free CKD-EPI eGFR equations using the laboratory data from a large tertiary hospital in BC and evaluate the impact on reclassification of eGFR category.

METHODS

Serum/plasma creatinine results and demographic data were collected from Vancouver General Hospital laboratory. The CKD-EPI 2009 without the race variable and CKD-EPI 2021 equations were computed. eGFR and its distributions were compared and reclassification of eGFR category was assessed across the full cohort and in specific patient populations.

RESULTS

The analysis included 58,763 patients. The median age was 57 years, with women comprising 51 % of the population. The median of eGFR changed from 85 to 90 mL/min/1.73 m2 using the CKD-EPI 2009 equation without the race variable and the CKD-EPI 2021 equation, respectively. The CKD-EPI 2021 equation reclassified 11.86 % of patients, mainly from G3a (45-59 mL/min/1.73 m2) to G2 (60-89 mL/min/1.73 m2). There was statistical significance between the non-renal and the renal population reclassified from G5 (<15 mL/min/1.73 m2) to G4 (15-29 mL/min/1.73 m2).

CONCLUSIONS

Using laboratory data representative of local populations, we observed an overall positive shift to higher eGFR, with 11.86 % of individuals having improved eGFR categories based on the CKD-EPI 2021 equation. This study provides insights into clinical implications at both the individual and population levels. The data-based approach is the first step towards adopting the CKD-EPI 2021 equation within the province.

Association of Kidney Function With Dementia and Structural Brain Differences: A Large Population-Based Cohort Study

BACKGROUND

The association between kidney function and dementia risk and the mechanisms underlying this relationship remain unclear.

METHODS

Within the UK Biobank, 191 970 dementia-free participants aged ≥60 (mean age: 64.1 ± 2.9 years) were followed for 16 years to detect incident dementia. Serum creatinine and Cystatin C were measured at baseline to calculate estimated glomerular filtration rate (eGFR, mL/min/1.73 m2). Kidney function was categorized as normal (eGFR ≥ 90), mildly impaired (60 ≤ eGFR < 90), or moderately to severely impaired (eGFR < 60). Dementia was assessed based on self-reported medical history and medical records. During the follow-up, a subsample of 12 637 participants underwent brain MRI scans. Volumes of total brain, gray matter, white matter, hippocampus, and white matter hyperintensities were assessed.

RESULTS

Over the follow-up, 5 327 (2.8%) participants developed dementia. Compared to normal kidney function, there was an increased risk of dementia with moderate to severely impaired kidney function (hazard ratio = 1.53, 95% confidence interval [CI]: 1.32-1.76) but not mildly impaired kidney function. In Laplace regression, dementia onset among people with moderate to severely impaired kidney function occurred 1.53 (95% CI: 0.98-2.08) years earlier than those with normal kidney function. Moderate to severely impaired kidney function was related to significantly lower gray matter volume (β = -0.11, 95% CI: -0.19 to -0.03), but not to other brain magnetic resonance imaging measures.

CONCLUSIONS

Impaired kidney function is associated with about 50% increased risk of dementia and anticipates dementia onset by more than 1.5 years. Brain neurodegeneration may underlie the kidney function-dementia association.

Long-term outcomes with rituximab as add-on therapy in severe childhood-onset lupus nephritis

BACKGROUND

Long-term data pertaining to rituximab as add-on therapy in childhood-onset lupus nephritis (cLN) is scarce.

METHODS

A retrospective cohort study was conducted on all patients with proliferative cLN, diagnosed ≤ 18 years and between 2005 and 2021, who received rituximab for LN episodes that were life/organ threatening and/or treatment resistant to standard immunosuppression.

RESULTS

Fourteen patients with cLN (female, n = 10) were included, with median follow-up period of 6.9 years. LN episodes (class III, n = 1; class IV, n = 11; class IV + V, n = 2) requiring rituximab occurred at 15.6 years (IQR 12.8-17.3), urine protein:creatinine ratio was 8.2 mg/mg (IQR 3.4-10.1) and eGFR was 28 mL/min/1.73 m2 (IQR 24-69) prior to rituximab treatment. Ten and four patients received rituximab at 1500 mg/m2 and 750 mg/m2, which were given at 46.5 days (IQR 19-69) after commencement of standard therapies. Treatment with rituximab resulted in improvements in proteinuria (ps < 0.001), eGFR (ps < 0.01) and serological parameters, including haemoglobin levels, complement 3 levels and anti-dsDNA antibodies, compared with baseline. Rates of complete/partial remission at 6-, 12- and 24-month post-rituximab were 28.6/42.8%, 64.2/21.4% and 69.2/15.3%. All three patients who required acute kidney replacement therapy became dialysis-free after rituximab. Relapse rate following rituximab was 0.11 episodes/patient-year. There was no lethal complication or severe infusion reaction. Hypogammaglobulinaemia was the most frequent complication (45%) but was mostly asymptomatic. Neutropenia and infections were observed in 20% and 25% of treatments. Upon last follow-up, three (21%) and two (14%) patients developed chronic kidney disease (stage 2, n = 2; stage 4; n = 1) and kidney failure, respectively.

CONCLUSION

Add-on rituximab is an effective and safe rescue therapy for cLN patients with life-/organ-threatening manifestations or treatment-resistance. A higher resolution version of the Graphical abstract is available as Supplementary information.

Assessing GFR With Proenkephalin

Introduction

In clinical practice, kidney (dys)function is monitored through creatinine-based estimations of glomerular filtration rate (eGFR: Modification of Diet in Renal Disease [MDRD], Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI]). Creatinine is recognized as a late and insensitive biomarker of glomerular filtration rate (GFR). The novel biomarker proenkephalin (PENK) may overcome these limitations, but no PENK-based equation for eGFR is currently available. Therefore, we developed and validated a PENK-based equation to assess GFR.

Methods

In this international multicenter study in 1354 stable and critically ill patients, GFR was measured (mGFR) through iohexol or iothalamate clearance. A generalized linear model with sigmoidal nonlinear transfer function was used for equation development in the block-randomized development set. Covariates were selected in a data-driven fashion. The novel equation was assessed for bias, precision (mean ± SD), and accuracy (eGFR percentage within ±30% of mGFR, P30) in the validation set and compared with MDRD and CKD-EPI.

Results

Median mGFR was 61 [44-81] ml/min per 1.73 m2. In order of importance, PENK, creatinine, and age were included, and sex or race did not improve performance. The PENK-based equation mean ± SD bias of the mGFR was 0.5 ± 15 ml/min per 1.73 m2, significantly less compared with MDRD (8 ± 17, P < 0.001) and 2009 CKD-EPI (5 ± 17, P < 0.001), not reaching statistical significance compared with 2021 CKD-EPI (1.3 ± 16, P = 0.06). The P30 accuracy of the PENK-based equation was 83%, significantly higher compared with MDRD (68%, P < 0.001) and 2009 CKD-EPI (76%, P < 0.001), similar to 2021 CKD-EPI (80%, P = 0.13).

Conclusion

Overall, the PENK-based equation to assess eGFR performed better than most creatinine-based equations without using sex or race.

Proteomic architecture of frailty across the spectrum of cardiovascular disease

While frailty is a prominent risk factor in an aging population, the underlying biology of frailty is incompletely described. Here, we integrate 979 circulating proteins across a wide range of physiologies with 12 measures of frailty in a prospective discovery cohort of 809 individuals with severe aortic stenosis (AS) undergoing transcatheter aortic valve implantation. Our aim was to characterize the proteomic architecture of frailty in a highly susceptible population and study its relation to clinical outcome and systems-wide phenotypes to define potential novel, clinically relevant frailty biology. Proteomic signatures (specifically of physical function) were related to post-intervention outcome in AS, specifying pathways of innate immunity, cell growth/senescence, fibrosis/metabolism, and a host of proteins not widely described in human aging. In published cohorts, the "frailty proteome" displayed heterogeneous trajectories across age (20-100 years, age only explaining a small fraction of variance) and were associated with cardiac and non-cardiac phenotypes and outcomes across two broad validation cohorts (N > 35,000) over ≈2-3 decades. These findings suggest the importance of precision biomarkers of underlying multi-organ health status in age-related morbidity and frailty.

Diagnostic challenges of diabetic kidney disease

Diabetic kidney disease (DKD) is one of the most common microvascular complications of both type 1 and type 2 diabetes and the most common cause of the end-stage renal disease (ESRD). It has been evidenced that targeted interventions at an early stage of DKD can efficiently prevent or delay the progression of kidney failure and improve patient outcomes. Therefore, regular screening for DKD has become one of the fundamental principles of diabetes care. Long-established biomarkers such as serum-creatinine-based estimates of glomerular filtration rate and albuminuria are currently the cornerstone of diagnosis and risk stratification in routine clinical practice. However, their immanent biological limitations and analytical variations may influence the clinical interpretation of the results. Recently proposed new predictive equations without the variable of race, together with the evidence on better accuracy of combined serum creatinine and cystatin C equations, and both race- and sex-free cystatin C-based equation, have enabled an improvement in the detection of DKD, but also require the harmonization of the recommended laboratory tests, wider availability of cystatin C testing and specific approach in various populations. Considering the complex pathophysiology of DKD, particularly in type 2 diabetes, a panel of biomarkers is needed to classify patients in terms of the rate of disease progression and/or response to specific interventions. With a personalized approach to diagnosis and treatment, in the future, it will be possible to respond to DKD better and enable improved outcomes for numerous patients worldwide.

Dietary fiber intake and cognitive impairment in older patients with chronic kidney disease in the United States: A cross-sectional study

BACKGROUND

High-fiber diet has been associated with better cognitive performance. However, the association between dietary fiber intake and cognition in older patients with chronic kidney disease (CKD) remains unknown. Hence, this study aimed to investigate the effect of dietary fiber intake on cognition in older patients with CKD.

METHODS

This study included participants aged ≥60 years who provided data on social demography, cognitive tests (Consortium to Establish a Registry for Alzheimer's disease Word Learning [CERAD-WL], CERAD Delayed Recall [CERAD-DR], Animal Fluency Test [AFT], and Digit Symbol Substitution Test [DSST]), diet, and other potential cognition-related variables from the National Health and Nutrition Examination Survey 2011-2014. Fully-adjusted multivariate logistic regression subgroup models were performed, and multiple linear regression analyses were employed to examine the association between dietary fiber intake and cognition in patients with CKD.

RESULTS

A total of 2461 older adults were included, with 32% who suffered from CKD. Participants with CKD scored lower in CERAD-WL, CERAD-DR, AFT, and DSST. Patients with CKD consuming low dietary fiber (≤25 g/day) had a higher risk of CERAD-WL and DSST impairments. High dietary fiber intake eliminated the differences in CERAD-WL and DSST impairments between the CKD and non-CKD participants. However, no associations were observed between CKD and CERAD-DR and AFT impairments regardless of dietary fiber intake. A positive linear relationship between dietary fiber intake and AFT score was observed in older patients with CKD.

CONCLUSION

High dietary fiber intake may benefit cognitive function in older patients with CKD. High-fiber diet management strategies could potentially mitigate cognitive impairment in this group of patients.

Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus

BACKGROUND

Numerous laboratory tests are used in the diagnosis and management of diabetes mellitus. The quality of the scientific evidence supporting the use of these assays varies substantially.

APPROACH

An expert committee compiled evidence-based recommendations for laboratory analysis in screening, diagnosis, or monitoring of diabetes. The overall quality of the evidence and the strength of the recommendations were evaluated. The draft consensus recommendations were evaluated by invited reviewers and presented for public comment. Suggestions were incorporated as deemed appropriate by the authors (see Acknowledgments). The guidelines were reviewed by the Evidence Based Laboratory Medicine Committee and the Board of Directors of the American Association for Clinical Chemistry and by the Professional Practice Committee of the American Diabetes Association.

CONTENT

Diabetes can be diagnosed by demonstrating increased concentrations of glucose in venous plasma or increased hemoglobin A1c (HbA1c) in the blood. Glycemic control is monitored by the people with diabetes measuring their own blood glucose with meters and/or with continuous interstitial glucose monitoring (CGM) devices and also by laboratory analysis of HbA1c. The potential roles of noninvasive glucose monitoring, genetic testing, and measurement of ketones, autoantibodies, urine albumin, insulin, proinsulin, and C-peptide are addressed.

SUMMARY

The guidelines provide specific recommendations based on published data or derived from expert consensus. Several analytes are found to have minimal clinical value at the present time, and measurement of them is not recommended.

J-shaped association of free triiodothyronine to free thyroxine ratio with 5-year mortality among patients with chronic kidney disease: a prospective cohort study

PURPOSE

To investigate the association of free triiodothyronine to free thyroxine (FT3/FT4) ratio with 5-year mortality in patients with chronic kidney disease (CKD) using data from the National Health and Nutrition Examination Survey (NHANES) through 2001-2002 and 2007-2012.

METHODS

Two thousand four hundred twenty-four patients with CKD stage 1-5 were included. Patients' baseline characteristics were collected. Cox proportional hazards models were used to investigate the association of FT3/FT4 ratio with 5-year all-cause and cardiovascular mortality. Subgroup analysis was performed.

RESULTS

Within 5 years of follow-up duration, 425 (17.53%) deaths were recorded, and 154 patients died from cardiovascular disease. A J-shaped association between FT3/FT4 ratio and 5-year mortality was observed. After fully adjustment, the elevated FT3/FT4 ratio was significantly associated with a decreased 5-year all-cause mortality risk (HR: 0.79, 95% CI 0.63-0.99) among patients with CKD stage 1-5 when FT3/FT4 ratio < 4.71, and is significantly associated with an increased 5-year all-cause mortality risk in CKD patients with advanced CKD stages or low UACR when FT3/FT4 ratio ≥ 4.71 (HR: 2.74, 95% CI 1.20-6.29; HR: 3.09, 95% CI 1.12-8.57, respectively). The elevated FT3/FT4 ratio also showed a J-shaped association with the 5-year cardiovascular mortality which disappears after fully adjustment.

CONCLUSION

The FT3/FT4 ratio is closely associated with 5-year mortality risk among patients with CKD, indicating a potential role of FT3/FT4 ratio as a biomarker for mortality prediction in CKD patients.

Discordance Between Creatinine-Based and Cystatin C-Based Estimated GFR: Interpretation According to Performance Compared to Measured GFR

Rationale & Objective

Use of cystatin C in addition to creatinine to estimate glomerular filtration rate (estimated glomerular filtration rate based on cystatin C [eGFRcys] and estimated glomerular filtration rate based on creatinine [eGFRcr], respectively) is increasing. When eGFRcr and eGFRcys are discordant, it is not known which is more accurate, leading to uncertainty in clinical decision making.

Study Design

Cross-sectional analysis.

Setting & Participants

Four thousand fifty participants with measured glomerular filtration rate (mGFR) from 12 studies in North America and Europe.

Exposures

Serum creatinine and serum cystatin C.

Outcomes

Performance of creatinine-based and cystatin C-based glomerular filtration rate estimating equations compared to mGFR.

Analytical Approach

We evaluated the accuracy of eGFRcr, eGFRcys, and the combination (eGFRcr-cys) compared to mGFR according to the magnitude of the difference between eGFRcr and eGFRcys (eGFRdiff). We used CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equations to estimate glomerular filtration rate. eGFRdiff was defined as eGFRcys minus eGFRcr and categorized as less than -15, -15 to <15, and ≥15 mL/min/1.73 m2 (negative, concordant, and positive groups, respectively). We compared bias (median of mGFR minus eGFR) and the percentage of eGFR within 30% of mGFR.

Results

Thirty percent of participants had discordant eGFRdiff (21.0% and 9.6% negative and positive eGFRdiffs, respectively). In the concordant eGFRdiff group, all equations displayed similar accuracy. In the negative eGFRdiff groups, eGFRcr had a large overestimation of mGFR (-13.4 [-14.5 to -12.2] mL/min/1.73 m2) and eGFRcys had a large underestimation (9.9 [9.1-11.2] mL/min/1.73m2), with opposite results in the positive eGFRdiff group. In both negative and positive eGFRdiff groups, eGFRcr-cys was more accurate than either eGFRcr or eGFRcys. These results were largely consistent across age, sex, race, and body mass index.

Limitations

Few participants with major comorbid conditions.

Conclusions

Discordant eGFRcr and eGFRcys are common. eGFR using the combination of creatinine and cystatin C provides the most accurate estimates among persons with discordant eGFRcr or eGFRcys.

The CKD-EPI 2021 Equation and Other Creatinine-Based Race-Independent eGFR Equations in Chronic Kidney Disease Diagnosis and Staging

BACKGROUND

Recent debate on the race correction factor in creatinine-based estimated glomerular filtration rate (eGFR) has led to the development of a new race-independent equation (Chronic Kidney Disease Epidemiology Collaboration, CKD-EPI_2021). Previously, some institutions have already modified the early version of the CKD-EPI or Modification of Diet in Renal Disease (MDRD) equations by removing the race factors (CKD-EPI_2009_non-Black (NB), MDRD_NB) for Black populations although this approach remains controversial.

METHODS

In this study, the CKD-EPI_2009_NB, MDRD_NB, and European Kidney Function Consortium (EKFC) equations were compared directly with the CKD-EPI_2021 equation in eGFR calculation, chronic kidney disease (CKD) diagnosis, and staging in a local population.

RESULTS

These 3 previous methods underestimated eGFR compared to CKD-EPI_2021 for eGFR < 90 mL/min/1.73 m2 but overestimated eGFR at the high end (>120 mL/min/1.73 m2). Around the CKD diagnosis cutoff (60 mL/min/1.73 m2), both MDRD_NB and EFKC equations resulted in an increase in CKD cases compared to CKD-EPI_2021. CKD-EPI_2009_NB demonstrated a similar trend although the difference was not statistically significant. In a population with low eGFR (<60 mL/min/1.73 m2), the EKFC equation showed a CKD staging pattern significantly different from that by CKD-EPI_2021, but all 3 previous methods resulted in a similar number of end-stage renal failure cases. In general, the EKFC equation demonstrated a weaker agreement in eGFR calculation and concordance in classification with the CKD-EPI_2021 equation than MDRD_NB and CKD-EPI_2009_NB.

CONCLUSIONS

Our study provides a direct visual comparison to demonstrate the potential clinical impact between 3 previously used race-independent methods and the CKD-EPI_2021 equation and aids the communication with healthcare providers during the implementation of this new equation.

COL4A3 Mutation Induced Podocyte Apoptosis by Dysregulation of NADPH Oxidase 4 and MMP-2

Introduction

Podocyte apoptosis is a common mechanism driving progression in Alport syndrome (AS). This study aimed to investigate the mechanism of podocyte apoptosis caused by COL4A3 mutations.

Methods

We recruited patients with autosomal dominant AS (ADAS). Patients with minimal change disease (MCD) were recruited as controls. Microarray analysis was carried out on isolated glomeruli from the patients and validated. Then, corresponding mutant human podocytes (p.C1616Y) and 129 mice (p.C1615Y, the murine homolog to the human p.C1616Y) were constructed. The highest differentially expressed genes (DEGs) from microarray analysis were validated in transgenic mice and podocytes before and after administration of MMP-2 inhibitor (SB-3CT) and NOX4 inhibitor (GKT137831). We further validated NOX4/MMP-2/apoptosis pathway by real-time polymerase chain reaction (PCR), immunohistochemistry, and western blot in renal tissues from the ADAS patients.

Results

Using microarray analysis, we observed that DEGs, including NOX4/H2O2, MMP-2, and podocyte apoptosis-related genes were significantly upregulated. These genes were validated by real-time PCR, histologic analysis, and western blot in corresponding mutant human podocyte (p.C1616Y) and/or mice models (p.C1615Y). Moreover, we found podocyte apoptosis was abrogated and MMP-2 expression was down-regulated both in vivo and in vitro by NOX4 inhibition, urinary albumin-to-creatinine ratio, 24-hour proteinuria; and renal pathologic lesion was attenuated by NOX4 inhibition in vivo. Furthermore, podocyte apoptosis was attenuated whereas NOX4 expression remained the same by inhibition of MMP-2 both in vivo and in vitro.

Conclusion

These results indicated that NOX4 might induce podocyte apoptosis through the regulation of MMP-2 in patients with COL4A3 mutations. Our findings provided new insights into the mechanism of ADAS.

Variation of eGFR reporting and CKD equations used in the United Kingdom

BACKGROUND

UK Clinical laboratories have been routinely reporting an estimated glomerular filtration rate (eGFR) based on creatinine measurements using an eGFR equation since the early 2000s. Though there have been recommendations to use enzymatic based creatinine assays, and a recommendation of which equation to use, there still remains a high degree of variation in calculated eGFR results.

METHODS

Data from the UK NEQAS for Acute and Chronic Kidney Disease Scheme have been reviewed to look at the CKD equations that are currently in use in the UK and the impact on eGFR results reported. The UK NEQAS for Acute and Chronic Kidney Disease has over 400 participants measuring creatinine across all major clinical biochemistry platforms.

RESULTS

An audit of EQA registration against results returned showed that in February 2022 at most 44% of registered participants were correctly reporting the 2009 CKD-EPI equation. At higher creatinine concentrations (which give rise to lower eGFR results), the spread of eGFRs is tight and there is little difference between results from different method principles. However, at lower creatinine concentrations, where it is known that there is more variation in creatinine depending on method choice, both method principle and eGFR equation choice can influence calculated eGFR. In some cases, this can impact CKD Stage classification.

CONCLUSIONS

CKD is a serious public health issue that requires accurate assessment of eGFR. Laboratories should be in constant dialogue with their renal teams about their creatinine assay performance and impact on eGFR reporting across their service.

New and old GFR equations: a European perspective

Glomerular filtration rate (GFR) is estimated in clinical practice from equations based on the serum concentration of endogenous biomarkers and demographic data. The 2009 creatinine-based Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI2009) was recommended worldwide until 2021, when it was recalibrated to remove the African-American race factor. The CKD-EPI2009 and CKD-EPIcr2021 equations overestimate GFR of adults aged 18-30 years, with a strong overestimation in estimated GFR (eGFR) at age 18 years. CKD-EPICr2021 does not perform better than CKD-EPI2009 in US population, overestimating GFR in non-Black subjects, and underestimating it in Black subjects with the same magnitude. CKD-EPICr2021 performed worse than the CKD-EPI2009 in White Europeans, and provides no or limited performance gains in Black European and Black African populations. The European Kidney Function Consortium (EKFC) equation, which incorporates median normal value of serum creatinine in healthy population, overcomes the limitations of the CKD-EPI equations: it provides a continuity of eGFR at the transition between pediatric and adult care, and performs reasonably well in diverse populations, assuming dedicated scaling of serum creatinine (Q) values is used. The new EKFC equation based on cystatin C (EKFCCC) shares the same mathematical construction, namely, it incorporates the median cystatin C value in the general population, which is independent of sex and ethnicity. EKFCCC is therefore a sex-free and race-free equation, which performs better than the CKD-EPI equation based on cystatin C. Despite advances in the field of GFR estimation, no equation is perfectly accurate, and GFR measurement by exogenous tracer clearance is still required in specific populations and/or specific clinical situations.