Evaluation of novel glomerular filtration rate estimation equations in adolescents and young adults with type 1 diabetes

Switching to the CKD-EPI but Not Modified FAS eGFR Formula Underdetects CKD Among Adolescents and Young Adults in México

BACKGROUND

Guidelines recommend switching the glomerular filtration rate (eGFR) estimation from the CKiD-U25 to the CKD-EPI formula at age 18. We investigated how this would affect chronic kidney disease (CKD) classification.

METHODS

Serum creatinine was enzymatically measured in 1061 samples from 914 community-based 10-23-year-olds from Tlaxcala, Mexico, a region where urinary biomarkers demonstrated early kidney damage associated with exposure to inorganic toxins in a pediatric population. We calculated their eGFR using CKiD-U25, modified Schwartz, the first and modified Pottel full-age spectrum (FAS), and CKD-EPI formulae. Correlation analysis characterized the CKD stage stratified by age and sex.

RESULTS

At baseline, the median age was 13 (IQR: 12, 15) years, and 55% were female. Median CKiD-U25 eGFR was 96.9 (IQR: 83.3, 113.3) mL/min/1.73 m2, significantly lower than the CKD-EPI eGFR, which was 140.8 (IQR: 129.9, 149.3) mL/min/1.73 m2 (p < 0.0001, Wilcoxon rank test). The mean bias was 36.99 ± 12.89 mL/min/1.73 m2. Pearson correlation was r = 0.8296 (95% confidence interval 0.0898-0.8474). There was a better correlation between the modified Schwartz (r = 0.9421 (0.9349, 0.9485)) and the Pottel FAS (r = 0.9299 (0.9212, 0.9376)) formulae. Agreement was deficient when the eGFR was >75 mL/min/1.73 m2 in younger age and female sex. Modified Schwartz identified 281 (26.4%) measurements as having CKD 2 and 3 (2+), U25 identified 401 (37.7%) measurements as having CKD 2+, FAS identified 267 (25.1%) and modified FAS identified 282 (30%) measurements as having CKD 2+, and CKD-EPI identified 51 (4.8%) measurements as having CKD 2+, respectively.

CONCLUSIONS

In this population, there needed to be better agreement between the various eGFR formulae. CKD-EPI identifies substantially fewer at-risk participants as having CKD.

Accuracy of Shorter Iohexol GFR Measurement Protocols in Individuals with Preserved Kidney Function

Key Points

Shorter measured GFR protocols are accurate and precise compared with the reference standard measured GFR protocol in patients with preserved GFR. These shorter protocols can potentially improve the adoption of GFR measurement more widely by reducing procedural time and cost.

Background

Measured GFR (mGFR) using exogenous tracers is recommended in a number of settings. Plasma one-compartment multisample protocols (MSPs) are the most commonly used, with iohexol being the dominant tracer. The accuracy of MSPs has mostly been evaluated in the setting of reduced GFR where delayed initial and final samples are recommended. Much less is known about MSPs when GFR is not decreased, and the default protocol tends to include initial sampling at 120 minutes and final sampling at 240 minutes after iohexol injection. The recent Kidney Disease Improving Global Outcomes 2024 Clinical Practice Guideline for the Evaluation and Management of CKD includes research recommendations for the development of shorter more efficient mGFR protocols. The objective of this study was to assess the performance of shorter MSPs with earlier initial (60 and 90 minutes) and final (150, 180, and 210 minutes) sampling times in individuals with preserved GFR. Reference mGFR (R-mGFR) was calculated using five samples collected between 120 and 240 minutes.

Methods

Four different combinations of shorter sampling strategies were investigated. Performance was evaluated using measurements of bias, precision, and accuracy (P2, P5, and mean absolute error).

Results

The mean R-mGFR of the 43 participants was 102.3±13.7 ml/min per 1.73 m2. All shorter mGFRs had biases <1 ml/min per 1.73 m2 and mean absolute error <1.6 ml/min per 1.73 m2. All shorter mGFRs were within 5% of the R-mGFR, and the majority were within 2%.

Conclusions

These results demonstrate that shortening the mGFR procedure in individuals with preserved GFR provides similar results to the current standard while significantly decreasing procedure time.

Fifteen-minute consultation: Management of albuminuria in children and young people with diabetes

Albuminuria is a marker of diabetic kidney disease. Raised albuminuria in children and young people with diabetes is associated with an increased risk of microvascular and macrovascular complications. This review provides guidance for paediatricians caring for children and young people with type 1 and type 2 diabetes on screening, investigations and treatments for albuminuria in line with relevant national and international recommendations.

Bone health in young adults with type 1 diabetes and progressive eGFR decline

BACKGROUND

Type 1 Diabetes (T1D) is associated with increased risk of fractures, worsened by presence of microvascular complications. This study's objective is to determine the impact of progressive decline in estimated glomerular filtration rate (eGFR) on bone biomarkers and bone microarchitecture in youth with T1D.

METHODS

Slopes of eGFR were calculated using measures obtained at four timepoints from adolescence to young adulthood. Participants were identified as eGFR decliners if eGFR decreased ≥ 3ml/min/1.73m2/year. Bone health was assessed in young adulthood by high resolution peripheral quantitative computed tomography (HRpQCT Xtreme CTII) and bone biomarkers; osteocalcin, procollagen 1 intact n-terminal pro-peptide (P1NP), c-terminal telopeptide (CTX), and bone specific alkaline phosphatase. The relationship between diabetes duration, glycated hemoglobin, body mass index (BMI) and vitamin D level on bone biomarkers and microarchitecture was evaluated. Linear regression analysis was used for the statistical analysis in this study.

RESULTS

Ninety-nine study participants were studied with longitudinal evaluation of eGFR over 7.4 ± 1.0 years with mean age of 14.7 ± 1.7 years at baseline. Cross sectional evaluation of bone was performed at 21.3 ± 2.1 years. 44% participants had eGFR decline and showed 5% higher cortical porosity diameter than non-decliners (p = 0.035). Greater diabetes duration was associated with higher trabecular separation (p = 0.004) and lower trabecular number (p = 0.01). Higher level of 25 hydroxy-vitamin D was associated with lower trabecular separation (p = 0.01). Elevated glycated hemoglobin (p = 0.0008) and BMI (p = 0.009), were associated with lower markers of bone formation.

CONCLUSION

Mild increase in cortical porosity diameter was found in youth with T1D and eGFR decline, however, overall measures of bone microarchitecture on HR-pQCT were similar between both groups and there were no statistically significant changes in bone biomarkers. Hence, skeletal impairments were limited in youth with different eGFR trajectories near peak bone mass. Longitudinal HR-pQCT studies are needed to further understand the impact of eGFR decline on bone microarchitecture. Optimal glycemic control, normal BMI and vitamin D status were supported by this study as important markers for good bone health.

Exploring the Motivational Drivers of Young Adults with Diabetes for Participation in Kidney Research

Understanding motivational drivers and barriers to patient participation in diabetes research are important to ensure research is relevant and valuable. Young adults with type 1 diabetes (T1D) completed a 31-question qualitative survey evaluating participant experience, understanding, and motivators and barriers to research involvement. A total of 35 participants, 19–28 years of age, 60% female, completed the survey. Motivating factors included personal benefit, relationship with the study team, curiosity, financial compensation, altruism, and nostalgia. Older participants (>22 years) reported higher levels of trust in the study team (p = 0.02) and their relationship with the study team positively influenced their decision to participate (p = 0.03). Financial compensation was a strong motivator for participants with higher education (p = 0.02). Age, sex, education level, and trust in the study team influenced participants’ understanding. Barriers included logistics and lack of familial support. Important motivational drivers and barriers to participation in research by young adults with T1D must be considered to increase research engagement and facilitate the discovery of new knowledge.