CKD-EPI Equation Research Articles

RISK FACTORS OF CHRONIC KIDNEY DISEASE

The prospective study was conducted in Tertiary Care Hospitals from June 2022 to June 2023 to evaluate risk factors for CKD in the local population. Six hundred subjects were included in the study who were screened for the risk factors of chronic kidney disease. The participants were screened for CKD using a questionnaire. CKD-EPI equation was used for exploring disease burden. Results showed that CKD subjects were more likely male, older, urban residents, were obese or overweight, and had cardiovascular disease, hypertension, and diabetes compared to those without CKD. In subjects with CKD, the most common risk factors were diabetes(32%), hypertension (65%), and anemia (40%). Sensitivity analysis was done using CKD – EPI equation, and results were compared with the MDRD-3 equation. The prevalence of CKD, according to CKD-EPI, was 16%. Prevalence of CKD stages I, II, III, IV, and V was 9%, 4.5%,4.5%,1%, and 1%, respectively. People were not well aware of the status of their condition. Primary care centers should screen patients with diabetes and hypertension for kidney disease. Early detection can retard progression and improve outcomes.

#3619 CKD EPI 2021 EQUATION FOR EGFR HAS GOOD EFFICACY TO PREDICT CLINICAL OUTCOMES IN A LARGE PROSPECTIVE COHORT OF ADULT KOREANS

Abstract Background and Aims A new eGFR equation using serum creatinine (CKD-EPI 2021) without race were developed by Chronic Kidney Disease Epidemiology Collaboration in 2021. We projected the changes of eGFR, CKD prevalence, and incidence of end stage renal disease (ESRD) and mortality in a large prospective cohort of adult Koreans who had voluntary health check-ups, using current (CKD-EPI 2009) and new equation (CKD-EPI 2021). Method We included 112,772 adult participants, aged 18 years or older, who had voluntary routine health check-ups including serum creatinine at three medical centers in Korea from 2003 to 2009. We compared the difference of eGFR and predictability of mortality and ESRD between eGFR values calculated by CKD-EPI 2009 and CKD-EPI 2021. Serum creatinine was expressed as the IDMS-traceable creatinine according to the manufacturer's conversion formula from the original value measured by the alkaline picrate Jaffe kinetic method. The incidence of mortality data was extracted from Statistics Korea and the ESRD data from the ESRD registry of the Korean Society of Nephrology. Results At baseline study, there were 60,723 males (53.8%). Age was 48.9 ± 12.0 years. The value of IDMS-traceable serum creatinine was 0.86 ± 0.21 mg/dl. Levels of eGFR at baseline study were 93.5 ± 15.6 ml/min/1.73 m2 by CKD-EPI2009, and 97.1 ± 15.0 ml/min/1.73 m2 by CKD-EPI2021. Values subtracted eGFRs by CKD-EPI2009 from eGFR by CKD-EPEI2021 were 3.6 ± 1.2 (range: -32.9∼6.1) ml/min/1.73 m2. The difference of eGFR was higher in males compared to females (p<0.001), was the highest in the oldest group among patients aged 18–44 years, 45–64 years, and 65 years or more (p<0.001). Patients with diabetes mellitus (DM) or hypertension showed higher difference of eGFR compared patients without DM or hypertension, respectively (each p<0.001). Patients with eGFR ≥120.0 ml/min/1.73 m2 by CKD-EPI 2009 showed the highest difference between two eGFRs compared to patients with the other values. CKD stage was improved in 11,828 (10.5%) participants using eGFR calculated by CKD-EPI 2021 instead of CKD-EPI 2009, however, only 0.63% of participants with eGFR <60 ml/min/1.73 m2 by CKD-EPI equation was reclassified into eGFR ≥60 ml/min/1.73 m2 by CKD-EPI 2021.During 11.6 ± 2.0 years, 3354 (3.00%) subjects were dead and 151 (0.13%) subjects had end stage renal disease (ESRD) before death. Any eGFR or stage of eGFR was an independent risk factors to ESRD or mortality estimated by Cox's hazard proportional model adjusted by related factors. AUC to estimate renal survival by eGFRs was not different between eGFRs by CKD-EPI2021 and CKD-EPI2009 [0.739 (0.687-0.790) vs 0.740(0.688-0.792), p = 0.170]. p<0.001]. AUC to estimate survival by eGFRs calculated through CKD-EPI equation was slightly higher than that by CKD-EPI2021 equation [0.673(0.664-0.682) vs 0.667(0.658-0.676), p<0.001], however, the difference of AUC was negligible [standard error of AUC difference by two eGFRs; 0.96 (95% CI; 0.006-0.007)]. Conclusion The eGFR calculated by CKD-EPI2021 was higher compared to eGFR calculated by CKD-EPI2009. The power to estimate renal survival was not different between eGFRs by CKD-EPI2021 and CKD-EPI2009.

#6929 SGLT2 INHIBITORS IN IGA NEPHROPATHY: REAL LIFE EXPERIENCE AT OUR CENTRE

Abstract Background and Aims SGLT2 inhibitors (SGLT2i) have a beneficial effect in diabetic and non-diabetic proteinuric chronic kidney disease (CKD), demonstrated in large randomized controlled trials. However, there is limited information about real life experience with SGLT2i in non-diabetic CKD like IgA nephropathy (IgAN). Method All patients with biopsy-proven IgA nephropathy since 2015 were evaluated for SGLT2i use. We collected data on age, gender, the use of renin-angiotension-aldosterone system inhibitors (RAASi), eGFR, glycosuria and proteinuria at baseline, at 6 months and at one year of follow-up. Glomerular filtration rate (eGFR) was estimated using the CKD-EPI equation. Data was analyzed using Jamovi®. Results 51 patients had IgAN diagnosed by kidney biopsy from April 2015 until March 2021. Eleven of these started SGLT2i between December 2020 and February 2022 (at their physician's description). Their median age was 52, nine were male and all were taking RAASi. The initial median proteinuria was 1 g/g (range 0.5-2.0 g/g), median eGFR was 57.5 mL/min (range 16.8-104 mL/min). At 6 months, the median proteinuria was 0.7 g/g (range 0.8-4.8 g/g), median eGFR was 42.6 mL/min (range 13.9-108 mL/min). One year after beginning SGLT2i, 8 patients have laboratory values and the median value of proteinuria was 0.85 g/g (range 0.2-3.0 g/g) and the median eGFR was 40.5 mL/min (range 14.5-85.4 mL/min). All patients had glycosuria at all urine evaluations confirming no discontinuations of the SGLT2i. No serious adverse events were reported and none of the patients needed dialysis or died. There were no significant differences between proteinuria and eGFR between evaluations at the start, 6 months and 1 year of follow-up. Conclusion SGLT2i have become important drugs in IgAN. Our first cases who started SGLT2i showed good compliance (using glycosuria as an indirect tool to monitor adherence) and no adverse events, irrespective of their initial eGFR. The small sample was probably a limitation to the lack of significant results.

#6545 URINARY FETUIN-A FRAGMENT EXCRETION IN PATIENTS WITH TYPE 2 DIABETES AND ITS CORRELATION WITH RENAL FUNCTION

Abstract Background and Aims Fetuin-A is associated with production of pro-inflammatory cytokines, which can lead to progression of vascular complications in patients with diabetes. We planned a study to evaluate the correlation of urinary excretion of post translationally modified fetuin-A fragment (PTM Fetuin A) with albuminuria and chronic kidney disease. Method We conducted a cross-sectional study between July to August 2022 in patients with type 2 diabetes. The baseline characteristics such as Age, Gender, history of Diabetes Mellitus, Hypertension, Cardiac disease, and CKD were obtained. The subject's blood pressure, Haemoglobin, Random blood sugar, Creatinine, was obtained, and eGFR (Glomerular Filtration Rate) was calculated using the CKD-EPI equation. The spot urine was tested for urine albumin to creatinine ratio (UACR) and PTM-Fetuin-A: Creatinine ratio (FCR). PTM-Fetuin A was measured by an ELISA using DNlite-IVD103 ELISA test kit, Bio Preventive Medicine Corp, Taiwan. Results A total of 68 subjects were included, with 37 being men (54.4%). The mean age, eGFR, UACR, and FCR were 55 ± 11.4 years, 61.9 ± 37.5 ml/min/1.73 m2, 1060.7 ± 1550 mg/g, and 522.2 ± 915.1 ng/g respectively. There was significant positive correlation between FCR and UACR (p<0.005), serum creatinine (p<0.005), and eGFR (p<0.001). There was a trend noted of increasing PTM-Fetuin A levels and UACR with worsening eGFR. The AUROC for UACR and FCR for predicting patients with CKD stage 3 onwards were 0.703 and 0.789 respectively (Figure 1). In our study, the significance of predicting CKD stage 3 onwards with a UACR cut-off of 300 mg/g, UACR cut-off of 1150 mg/g and a FCR cut-off of 123 ng/g were p = 0.008, p = 0.003, and p<0.0001 respectively. Conclusion PTM-Fetuin A is significantly associated with worsening renal function. It has very significant correlation with the albuminuria, and at a FCR cut-off of 123 ng/g, it could significantly differentiate CKD stages, compared to UACR. Further prospective studies are needed to evaluate the correlation between PTM-Fetuin A levels and rate of progression of nephropathy.

#6260 PREDICTING KIDNEY FUNCTION AND END-STAGE KIDNEY DISEASE IN ANCA-ASSOCIATED VASCULITIS USING ANCA, C-REACTIVE PROTEIN AND C3

Abstract Background and Aims Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) are systemic autoimmune diseases that involve small- and medium-sized blood vessels. AAV compromises the overall survival of patients, and its kidney involvement can lead to end-stage kidney disease (ESKD). Our aim was to determine whether the serum C3, C-reactive protein (CRP) and ANCA levels could predict kidney survival. Method We retrospectively reviewed patients with AAV and kidney involvement (n = 62) from 2006 to 2022. Demographic, clinical and laboratory data were collected. Patients’ ANCA title were measured by ELISA, and Glomerular Filtration Rate (GFR) was estimate by CKD-EPI equation. ANCA, C3 and CRP were measure at diagnosis, remission, and last follow-up. ANCA was analyzed as continuous and categorical variable. We analyzed factors associated with dialysis dependency at diagnosis and evolution to ESKD. Multivariable adjusted Cox regression analysis was performed for assessing predictive variables associated with dialysis outcome. Results The cohort included 62 total patients, with median age of 69 (63-77) years old, 44% were female, 35.5% (n = 22) presented with alveolar haemorrhage, 82.3% (n = 51) were MPO-ANCA+ and 4 patients had concomitant anti-GBM+. At admission, the median ANCA title was 80.5 UI/mL (36.75- 112.25), C3 was 108.5 mg/dL (90-130.25) and CRP 7.5 mg/dL (2.14-14.34). The GFR was 11.17±11.16 at admission and 24% of patients required dialysis at admission (n = 15). At 3 months 30% (n = 19) required dialysis, 10% at 6 months (n = 6) and 5% at 1 year (n = 3). The median time until dialysis was 488.98 (0-5702) days. Twenty (32.3%) patients died during the study period. The title of ANCA at admission, as categorical variable, did not associate with requirement of kidney replacement therapy during follow-up (p = 0.870) nor as a continuous variable (p = 0.523). Considering C3 and CRP, only low C3 at last follow-up correlates with ESKD (p = 0.028). Median C3 at last follow-up was 91.5 mg/dl (79.5-107) in ESKD patients and 114.5 mg/dl (92-142.75) in patients that do not require dialysis. In the cox regression analysis of kidney survival, C3 levels at last follow-up were significantly associated with a shorter time until dialysis (p = 0.006). In a multivariate analysis, including age and gender, C3 levels at last follow-up lost significance to predict time until ESKD (p = 0.083, model p = 0.005). Initial GFR was not correlated with ANCA title at admission (r = 0.220, p = 0.205) nor as a categorical variable (p = 0.592). At remission, GFR was not correlated with ANCA title (r = 0.383, p = 0.349). Considering factors associated with the need for dialysis at admission, only CRP levels at admission were significantly higher (p = 0.035) in those who required dialysis. ANCA title and C3 at admission did not correlate with dialysis at admission (p = 0.875, p = 0.702). In multivariate analysis, including age and gender, CRP maintain its significancy (p = 0.036, model p = 0.044). Conclusion C3 and CRP levels have been studied as possible factors predicting kidney survival, however, results are not consistent. CRP is a marker of inflammation and C3 represents complement activity, these serologic markers could be important to identify patients at risk for ESKD. In our study CRP levels seems to be related to dialysis requirement at admission. These patients should be followed more closely and carefully to improve kidney survival.

#6279 ESKD TREATMENTS: A DIFFICULT CHOICE TO ELDERLY PATIENTS?

Abstract Background and Aims End stage kidney disease (ESKD) treatment choice may be very difficult mainly for elderly patients. Dialysis can be burdensome for the frail patients, offering more aggressive procedures and less quality of life. Conservative Care (CC) may shorten life in a fit patient. This study aimed to describe our elderly patients' choices when it comes to CKD treatment options and reflect about them. Method We designed a single center retrospective observational, cross-sectional study regarding patients (pts) over 80 years old (yo) who attend the appointment of ESKD treatment modalities between July 2015 and and December 2021, since a Conservative Care Program is available in our hospital. Results During these 6,5 years, 113 pts over 80 yo were attended. Mean age was 85 yo (range 80–103). 66% were male and mean charlson comorbidity index (CMI) was 7 (sd ± 1,2). Mean seric creatinine was 3,69 mg/dl (sd 0,99; range 1,8-7,0). Mean estimated glomerular filtration rate was 17,41 (sd ±4,12) and 14,64 (sd ± 7,6) ml/min per 1.73 m2 when calculated with BIS1 and CKD-EPI equation, respectively. Two patients were already on a regular program of dialysis. Regarding CKD etiology, 31,9% was from multifactorial origin, 27,4% was from undetermined origin, 10,6% was hypertensive, 8% was diabetic, 6,2% was from chronic pyelonephritis and 9,7% was in the context of cardiorenal syndrome. Regarding treatment options, 54% chose hemodialysis, 38,9% chose conservative care (CC), 2,7% chose peritoneal dialysis and 2,7% refused any treatment. We also observed a significant increase in the CC during these 6.5 years of study. Of those who chose hemodialysis, 22,95% (n = 14) died before starting on a regular program of dialysis, 62,3% (n = 38) actually started on a regular program and 14,75% (n = 9) still maintain follow-up in nephrology appointment. Regarding those who died before starting on dialysis treatment, the mean time between choosing dialysis and death was 1,36 years (range 115 days to 5,46 years, median 1,36 years), and between starting on a regular program and death was 1,38 year (range 11 days to 4,9 years). The main cause of death was unknown (66%) (by lack of data), followed by infectious cause (26,6%). Considering those who chose CC, 31,8% (n = 14) died before starting the regular follow up, 54,5% (n = 24) are on a regular program of follow up, and 4,5% (n = 2) lately decided for dialysis. Regarding those who died before CC, the mean time between choosing it and death was approximately 1 year (range 29 days to 3,4 years), and between starting on a regular follow up and death was 0,68 years (range 14 days to 1,7 years). We didn’t find any statistical significance between CMI and the ESRD modality chosen (p = 0.709) or the occurrence of death (p = 0,496). Conclusion Even considering the poor prognosis and the high mortality rate, the majority of patients over 80 years old still chose dialysis over conservative kidney treatment. In our cohort, there was no survival benefit from those who choose dialysis instead of CC. CC should be offered as an alternative treatment to all the patients who may not benefit from dialysis. It is important to find tools who help us to guide patients in the best suitable choice in regard to ESKD treatments.

#3897 STRUCTURAL AND FUNCTIONAL CHARACTERISTICS OF THE HEART IN ELDERLY AND OLD PATIENTS WITH CHRONIC KIDNEY DISEASE AND ATRIAL FIBRILLATION

Abstract Background and Aims The study of cardiorenal relationships is an important area in medicine. The presence of chronic kidney disease (CKD) and atrial fibrillation (AF) in elderly and old patients requires a special integrated approach in diagnosis and treatment, taking into account the principles of patient orientation. The aim was to study of structural and functional characteristics of the heart in elderly and old patients with CKD and AF. Method 224 female and 215 male patients of elderly and old age (mean age 72.4±6.8 years) with AF were examined. Among elderly and old patients, the following types of AF were diagnosed: a permanent form was observed in 136 (30.9%), a persistent form - in 117 (26.7%), a long-term persistent form - in 98 (22.3%), a paroxysmal form - in 88 (20.1%). Glomerular filtration rate (GFR) was determined using the CKD-EPI equation. All patients underwent electrocardiography (ECG), echocardiography (EchoCG), and some patients underwent ECG monitoring by Holter with assessment of rhythm variability. Results CKD with GFR<60 ml/min/1.73m2 was diagnosed in 274 (62.4%) patients with AF: stage 3a – in 184 (67.2%), stage 3b – in 82 (29.9%), 4 stage - in 8 (2.9%) patients with CKD. When analyzing the structural and functional parameters of the heart, more than half of elderly and old patients with CKD had concentric left ventricular hypertrophy - 146 (53.3%), 65 (23.7%) patients had eccentric hypertrophy. The types of remodeling in elderly and old patients did not differ depending on the presence of CKD (p>0.05). The ejection fraction (EF) of the left ventricle in elderly and old patients did not differ depending on the presence of CKD (p = 0.5). Preserved left ventricular EF had 194 (70%) intermediate - 60 (21.7%), low - 23 (8.3%) elderly and old patients with CKD. In patients with AF and CKD, compared with patients without CKD, mitral regurgitation (p = 0.006) and aortic regurgitation (p = 0.02) were more frequently observed. Left atrial (LA) diameter, exceeding the norm, was observed in most patients regardless of the presence of CKD: in 191 (69.7%) patients with CKD and 118 (71.5%) without CKD (χ2 = 0.03, p = 0.86). Moderate and pronounced increase in LA diameter was observed in 111 (40.1%) patients with CKD and 63 (38.1%) without CKD (χ2 = 0.17, р = 0.67). When analyzing the LA index, an increase in size was observed significantly more often in patients with CKD than in patients without CKD: 79 (28.8%) and 25 (15.2%), respectively, χ2 = 10.75, p = 0.001. Enlargement of the right ventricle was detected in 94 (34.3%) patients with CKD and 53 (32.1%) without CKD (χ2 = 0.18, p = 0.67), right atrium – 35 (12.8%) patients with CKD and 19 (11.5%) without CKD (χ2 = 0.15, p = 0.7). Attention is drawn to the differences in the spectral analysis of the heart rate in elderly and old patients with CKD compared with patients without CKD: a higher index of centralization (0.55 (0.33-0.86) and 0.36 (0.25-0.48), respectively, p = 0.03) and a lower index of vagosympathetic interaction (1.48 (0.85- 2.32) and 3.16 (2.12- 4.59), p = 0.004). Conclusion When analyzing the structural and functional parameters of the heart in elderly and old patients with AF and CKD, there was an increase in the LА index, more frequent presence of mitral and aortic regurgitation compared to patients without CKD. Elderly and old patients with CKD had a lower index of vagosympathetic interaction compared to patients without CKD.

#4360 FACTORS ASSOCIATED TO RENAL REMISSION IN CRESCENTIC GLOMERULONEPHRITIS

Abstract Background and Aims Impaired renal function is one of the most relevant factors associated to crescentic glomerulonephritis (CGN) prognosis. However, renal remission has not yet been defined and clinicians are required to use systemic scores (such as BVAS) to predict severity. In this retrospective study, we aim to describe the associated factors to long-term chronic dialysis incidence and survival in CGN. Method We included all biopsy-proven CGN of our center between 2004 and 2022. At baseline, demographics, treatments and comorbidities were collected. Renal function was assessed by glomerular filtration rate (GFR) using CKD-EPI equation, quantification of proteinuria and demonstration of hematuria. During follow-up (median 1486, interquartile range [25-3082] days) renal and vital status was evaluated. Factors associated to dialysis requirement were assessed using Cox regression models. A combined endpoint of death and dialysis was established. Factors associated to the combined endpoint were assessed. Results We included 47 CGN (77% female, 67±15 years). Of them, 35 (75%) presented positive ANCA antibodies, 3 (6%) positive glomerular basement membrane (GBM) antibodies, 8 (17%) ANCA and GBM antibodies and one (2%) presented negative autoimmunity. Induction treatment was based on prednisone and cyclophosphamide in 43 patients (91%), prednisone and rituximab in 3 (6%) and prednisone alone in one (2%). At admission, median CKD-EPI was 11 (11-21) ml/min/1.73 m2, proteinuria was 1030 (552-1872) mg/g and 43 (91%) patients presented hematuria. Nineteen patients (40%) required dialysis at admission. Following the definition of KDIGO guidelines for renal remission, 28 (64%) patients achieve it at 6 months. During follow-up, fifteen patients (36%) started chronic dialysis. Factors associated to chronic dialysis were the type on CGN (dual ANCA and GBM and GBM (+) vs ANCA (+), p = 0.003), CKD-EPI at admission (p = 0.001), AKIN (p = 0.050), requirement of dialysis at admission (p<0.001), percentage of crescents (p = 0.037), proteinuria at admission (p = 0.046) and remission after induction treatment (p<0.001). Twenty-four patients (53%) died or needed dialysis during follow-up. Factors associated to this combined endpoint were CKD-EPI at admission (p = 0.017), type on CGN (dual ANCA and GBM vs others, p = 0.003) (Figure 1), debut in dialysis (p<0.001), remission after induction treatment (p<0.001). An adjusted Cox regression model demonstrated that the need for dialysis or death during follow-up was independently associated to not achieving remission after induction (i.e. 6 months) (HR 8.78, 95%CI (2.88-26.7), p<0.001) and requirement of dialysis at debut (HR 3.96, 95%CI [1.15-13.6], p = 0.029). Conclusion The requirement of dialysis at debut and not achieving remission after induction are independent predictors of death or need for chronic dialysis in CGN.

#3390 ADPKD PREDICTOR: A CLOUD-BASED PROGNOSTIC TOOL FOR AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE

Abstract Background and Aims ADPKD is a progressively debilitating genetic disease characterized by the growth of numerous cysts in the kidneys, leading eventually to end-stage renal disease. Total Kidney Volume (TKV) is accepted by FDA and EMA as a prognostic biomarker and quantitative predictor of kidney function decline, and is currently used to select patients to receive Tolvaptan treatment. However, TKV calculation from manual tracing of medical images is labor-intensive; for better accuracy, current available methods involve the injection of an iodinated contrast medium for CT scan, with important limitations in patients with impaired renal function. We developed ADPKD Predictor, a user-friendly cloud-based tool for fast and accurate estimation of disease classification and progression, based on automated kidney and cysts segmentation from MRI data. Method An online tool was designed on Microsoft Azure Cloud to automatize the set-up and running of a previously developed algorithm implemented in MATLAB to automatically detect kidneys and cysts contours from MRI data (T2-weighted turbo-spin-echo SPIR), based on advanced image processing techniques [1]. Through the web interface, the user is requested to upload the MRI data and select one point inside kidney's parenchyma in the central slice (Figure 1). Then, TKV is automatically calculated and eGFR based on CKD-EPI equation, ADPKD Imaging Classification and future eGFR [2], estimated Tolvaptan treatment effect [3], and GFR Category based on KDIGO CKD staging system are obtained (Figure 2). The MRI dataset is anonymized before upload to the cloud; data and results are stored in a secure and reliable environment controlled by the user. Results The proposed solution is very fast and precise compared to manual segmentation of medical images (absolute mean error 2.4% ± 2.7%) [1]. Moreover, it is faster and more accurate than the commonly used ellipsoid-based method, resulting in a manifold reduction of misclassification error (2.5%) [1] and therefore potential therapeutic consequences. Another advantage is its usability, with no specific computational expertise, numerical software or dedicated hardware required, since all computations are run remotely in the cloud. Conclusion ADPKD Predictor provides a fast and reproducible assessment of risk classification and disease progression, based on precise morphologic classification of the renal and cysts volume of patient. The proposed solution represents an extremely useful tool for researchers and clinicians to easily obtain an accurate estimation of risk classification potentially helping in a correct and effective stratification of patients, and monitor patient's disease progression, hence supporting a correct and effective therapy administration. Also, it would represent a great benefit for the patient, since the tool analyzes medical images obtained without the use of contrast medium.

#6754 THE EFFECT OF REDUCED RENAL FUNCTION ON SEXUAL DYSFUNCTION IN PATIENTS WITH HEART FAILURE

Abstract Background and Aims Sexual Dysfunction is a common and often undiagnosed complication in patients with Heart Failure (HF) or Chronic Kidney Disease (CKD). Sexual dysfunction presents a strong association with cardiovascular disease and death. This study aims to evaluate the possible effect of reduced renal function on sexual dysfunction in patients with heart failure. Method This is a prospective case-control study in patients with Hearth Failure (clinical diagnosis based on relevant symptoms and/or signs) with preserved or reduced renal function, defined as estimated glomerular filtration rate (eGFR) ≥60 and <60 ml/min/1.73 m2, matched for age (± 5 years). The eGFR was calculated with the CKD-EPI equation. Sexual dysfunction was evaluated with the validated Female Sexual Function Index Scoring (FSFI) and the International Index of Erectile Function (IIEF) questionnaires in the native language. Results A total of 214 (107 per group) patients were included in this study. Patients’ age 74.10±8.97 vs 75.81±8.66; P = .157), gender (males: 65.4% vs 57.9%; P = .261) and BMI (28.10±4.90 vs 28.99±4.43; P = .164) were not different between the two study groups. In total population, sexual dysfunction was lower in patients with eGFR≥60 compared to <60 ml/min/1.73 m2 (75.7% vs 88.8%; P = .012). In females, no significant differences were evidenced in sexual dysfunction based on FSFI score <26.0 (91.9% vs 95.6%; P = .490). In contrast, males with preserved renal function had lower prevalence of sexual dysfunction (IIEF<22) compared to those with reduced renal function (67.1% vs 83.9%; P = .027). In regression analysis eGFR was an independent factor associated with sexual dysfunction. Conclusion Renal dysfunction may be an important factor predisposing heart failure patients to more frequent sexual dysfunction.

#3125 EXTERNAL VALIDATION OF A NOVEL MULTIMARKER GFR ESTIMATING EQUATION

Abstract Background and Aims The use of multiple markers may improve the accuracy in glomerular filtration rate (GFR) estimation especially when the interpretation of creatinine and cystatin C is limited. We sought to externally validate a recently developed multi-marker nuclear magnetic resonance (NMR)-based estimated GFR equation (eGFR-NMR) using the biracial Genetic Epidemiology Network of Arteriopathy cohort. Method We included 224 sex, race/ethnicity, and mGFR-category-matched participants. GFR was measured using urinary clearance of iothalamate (mGFR). We calculated eGFR-NMR using serum creatinine, valine, myo-inositol, and cystatin C, age, and sex. We compared the reliability of eGFR-NMR with current eGFR equations (2021 Chronic Kidney Disease Epidemiology Collaboration equations for creatinine [eGFR-Cr] and creatinine with cystatin C [eGFR-Cr-CysC]) using median bias, precision, and accuracy metrics. In particular, we evaluated its performance in age, sex, and race subgroups. Results In the overall cohort, mean age was 63 (±8) years, 54% were females, 49% were Black individuals, and mean mGFR was 78.7 (±24.3) ml/min/1.73 m2. eGFR-NMR overestimated mGFR by 2 mL/min/1.73 m2 (95% CI, 4 to 0.7) while eGFR-Cr-CysC underestimated mGFR by −5 mL/min/1.73 m2 (95% CI, −2 to −7). All equations had acceptable accuracy metrics. When stratified by age, sex, and race, eGFR-NMR performed the best among Black males age <65 years compared to current equations (Figure 1). In this subgroup, eGFR-NMR was unbiased (bias, 2mL/min/1.73 m2 [95% CI, -3 to 10]) compared to substantial biases of eGFR-Cr (bias, 17 mL/min/1.73 m2 [95% CI, 9 to 24]) and eGFR-Cr-CysC (bias, 15 mL/min/1.73 m2 [95% CI, 6 to 20]). In other subgroups, measures of accuracy for eGFR-NMR, eGFR-Cr, eGFR-Cr-CysC were generally similar. Conclusion eGFR-NMR can be used to estimate mGFR and was more accurate than CKD-EPI equations among Black males age <65 years.

#5817 EPIDEMIOLOGY OF CHRONIC KIDNEY DISEASE AND COMORBID ILLNESS IN OLDER HOSPITALIZED PATIENTS

Abstract Background and Aims The number of older people in Europe is expanding. Although chronic kidney disease (CKD) becomes more common with increasing age, data concerning epidemiology of CKD in older people are scarce, especially in Eastern Europe countries. These patients have multiple chronic conditions that must be correctly quantified for guiding risk stratification and subsequent management. Previously, European Renal Best Practice (ERBP) guidelines shed some light on managing older patients with advanced CKD, by stimulating the implementation of validated tools for predicting the most critical risks (death and progression to end-stage renal disease). Risk stratification can further inform decisions about the intensity of care (dialysis versus conservative treatment). In the current analysis, we aimed to fill the gap in CKD epidemiology in older people from Romania by describing a large population of hospitalized geriatric patients. Method In this retrospective cohort study, we included all patients aged ≥ 65 years hospitalized in the Geriatric Department of “Dr. C. I. Parhon” Hospital from Iași, Romania, between 2012 – 2022. This Geriatric Unit covers the entire North-East region of the country, so patients are representative of a population of almost 4 million people. CKD was identified as decreased estimated glomerular filtration rate (<60 ml/min/1.73 m2) according to CKD-EPI equation. We investigated comorbid conditions including diabetes mellitus, hypertension/hypertensive heart disease, coronary artery disease, congestive heart failure, atrial fibrillation, chronic respiratory failure and anemia. Results 3563 geriatric patients (59,2% females) were hospitalized between 2012–2022, totalling 5124 hospital admissions. The most common diagnosis was congestive heart failure (1958 cases, 38,2%) frequently due to hypertensive heart disease (877 patients, 44.8% of CHF cases). 3116 patients (87,4% of the total population) had a serum creatinine assay. Among these patients, the prevalence of CKD using the CKD-EPI equation was 32%. The mean age of CKD patients was 79 years, gender distribution was unequal (63,4% females) and almost half of them (49,1%) had stage 3a CKD. The most frequent comorbidities in patients with CKD were congestive heart failure (33%), diabetes (19%) and hypertension (17%), followed by atrial fibrillation (11%), chronic respiratory failure (9%), coronary artery disease (6%) and anemia (3%). The distribution of CKD patients stratified by the number of comorbidities showed that 86,7% had ≥ 2 comorbidities. The largest CKD subgroup was the one that associated three comorbidities (315 patients, 31.5%), followed by two subgroups that had two comorbidities (249 patients, 24,9%), respectively four comorbidities (189 patients, 18.9%). Only a minority of CKD patients (24 adults, 2,4%) had no other chronic condition. Conclusion With the ageing of the population, cardiovascular disease is becoming more common. In our population of geriatric patients, heart failure was the leading cause of hospitalization and the most frequent comorbid condition in CKD patients. One in three adults ≥ 65 years had CKD, a finding similar to other literature data. We emphasized that in older adults, CKD is not an isolated entity, which makes caring for these patients challenging, especially if we add the negative impact of other superimposed geriatric syndromes like frailty and cognitive decline.

#5673 ESTIMATING AND VALIDATING MEASURES OF CKD PREVALENCE AND INCIDENCE USING OBSERVATIONAL AND CLAIMS DATA IN PERSONS AGED 70+

Abstract Background and Aims Estimating prevalence and incidence of chronic kidney disease (CKD) based on claims data often underlies bias and limitations due to uncertainty of diagnostic validity. We investigated CKD prevalence and incidence over time using data from a community-dwelling cohort of individuals aged 70+ linked to individual claims data. We assessed the diagnostic validity of the claims-based compared with the eGFR-based CKD definition. Method We assessed CKD prevalence and incidence in two data sources: 1) eGFR values of participants aged 70+ (n = 2,069) of the Berlin Initiative Study (BIS), including five biennial study visits from 2009-2019, and 2) claims data of BIS participants matched on person-level. Using eGFR, we defined CKD prevalence as eGFR <60 ml/min/1.73m² calculated with the creatinine-based CKD-EPI (2009) equation. For each study visit, prevalent CKD cases were considered as incident if eGFR was ≥60 ml/min/1.73m² in the respective previous study visit. In claims data, in- and outpatient ICD-10 diagnoses (N18.3, N18.4, N18.5, N18.8, N18.9, N19) in the year preceding and/or following the study visit date were used to determine CKD prevalence. Incidence was defined as prevalent cases without a diagnosis in the year preceding the first CKD diagnosis. The denominator for incidence was defined as all persons at risk, i.e., who were not prevalent in a respective previous study visit and still under observation. We assessed the diagnostic validity of claims-based CKD prevalence and incidence using eGFR data as a reference. Analyses were stratified by sex. Results Between 2009 and 2019, CKD prevalence increased from 0.42 to 0.51 based on eGFR and from 0.30 to 0.43 based on claims data. Incidence varied between 0.16–0.22 using eGFR and 0.07–0.13 using BIS claims data. There was no clear time trend for incidence in any data source. Diagnostic validity of claims-based CKD prevalence and incidence detection is displayed in Table 1. Sensitivity for prevalence increased while other indicators remained stable over time. Detection of incident cases showed lower sensitivity (0.18–0.30 vs. 0.58–0.70) and PPVs (0.40–0.60 vs. 0.79–0.83) compared to prevalence, respectively. Prevalence and incidence based on claims data were slightly higher in males compared to females (Figure 1). Conclusion Using the eGFR-based or claims-based definition of CKD we found an increase in prevalence between 2009 and 2019. This might be due to the introduction of the KDIGO guidelines in 2012. During the same time, CKD incidence rates were stable. Comparing the claims-based with eGFR-based CKD definition, we found a sensitivity of 0.58-0.70 for prevalence and 0.18-0.30 for incidence, indicating that there is a risk of underdetection of CKD when using solely claims data, in particular for incident cases.

#4457 IONIZED MAGNESIUM LEVELS IN PATIENTS WITH MODERATE-TO-ADVANCED CHRONIC KIDNEY DISEASE: RELATIONSHIP WITH TOTAL MAGNESIUM AND ASSOCIATED FACTORS

Abstract Background and Aims Magnesium (Mg) is involved in a multitude of essential physiological processes. In chronic kidney disease (CKD), the mechanisms compensating for the decrease in glomerular filtration rate (eGFR) become insufficient and Mg excretion tends to decrease, potentially resulting in hypermagnesemia. On the other hand, hypomagnesemia seems also to be common in CKD, due to changes in Mg intake through diet, reduced absorption and drug-induced hypomagnesemia. To date, a few studies have shown an association between increased cardiovascular risk in CKD and either low or high total Mg levels. However, the physiologically active fraction of extracellular Mg is ionized Mg (iMg), which is not routinely measured. In critical ill patients, the correlation between iMg and total Mg has been shown to be poor. Similar data on patients with CKD would be important to future studies aiming at clarifying the link between Mg and outcomes, and ultimately to determine the interest of iMg assay in routine practice. The objectives of this study are i) to study the correlation between total Mg and iMg and ii) to evaluate the relation between serum ionized magnesemia, estimated GFR (eGFR) and demographic and biologic parameters. Method CKD-REIN is a French, prospective, nationally representative cohort study of 3033 CKD patients under nephrology care not receiving maintenance dialysis (stage 3-5: eGFR<60 mL/min/1.73 m² based on 2009 CKD-EPI equation). Baseline iMg and total Mg serum concentrations were respectively centrally measured using the NOVA BIOMEDICAL Stat Profile PRIME ES analyser and with Atellica® CH SIEMENS analyser. Normal range of serum total Mg considered was 0.66 to 1.06 mmol/L (from Atellica®). Mean ± standard deviation (SD) ionized Mg level evaluated in a cohort of 457 healthy volunteers (age = 45 ± 17 years; eGFR = 72.3 ± 13 mL/min/1.73m²) was 0.49 ± 0.05 mmol/L (median [tertile 1 – tertile 3] = 0.49 [0.45-0.52] mmol/L). Correlation between iMg and total Mg was estimated overall. Multivariate linear regressions were performed to identify factors associated with iMg and total Mg levels. Results Among 1741 patients with iMg and total Mg at baseline, the median age was 68 years [59-76], 65% were men, and the mean eGFR was 35 ± 14 mL/min/1.73m². The mean baseline iMg level was 0.48 ± 0.1 mmol/L, 615 patients had an ionized Mg <0.45 mmol/L (Tertile 1), 599 had an iMg between 0.46 and 0.52 mmol/L (Tertile 2), and 527 had an iMg >0.52 mmol/L (Tertile 3). Compared to healthy volunteers, mean iMg levels were significantly lower in CKD patients. However, the difference was small (difference CKD-heatlhy = 0.01 mmol/L). Most of patients were within the total Mg normal range (n = 1522), 12% (n = 208) and 1% (n = 11) presented hypo- and hypermagnesemia, respectively. Correlation between iMg and total Mg was very high (r = 0.88; p<0.001). (Figure). Ionized Mg was weakly inversely correlated with eGFR (r = -0.22; p<0.001). Consequently, the mean iMg level differed according to CKD stages, being more elevated in the advanced stages (0.45 mmol/L in stages 2-3A; 0.47 mmol/L in stage 3B; 0.50 mmol/L in stages 4-5 (p<0.001)). In a fully adjusted linear regression model, iMg concentration was significantly associated with age, decline of eGFR, history of cardiovascular disease and the use of diuretics, and inversely associated with calcium and triglycerides levels, systolic blood pressure, diabetes, and the use of proton pump inhibitors and potassium chelators. The same factors were associated with total Mg. Conclusion Total Mg and iMg were strongly correlated. Decline of kidney function was associated to an increase of iMg in patients with moderate-to-advanced CKD. Additional studies need to compare the difference between total Mg and iMg as a biomarker to predict hard outcomes.

#4427 USING REDUCED RANK REGRESSION TO INVESTIGATE THE RELATIONSHIP BETWEEN DIETARY PATTERNS AND ADULT KIDNEY FUNCTION IN THE GENERAL POPULATION

Abstract Background and Aims Chronic kidney disease (CKD) is a severe public health burden, characterized by a gradual loss of kidney function over time. Diet is a modifiable lifestyle-related risk factor for CKD. However, there is uncertainty about which specific dietary patterns (DPs) are more beneficial or detrimental in CKD prevention. We aimed at deriving DPs using an hybrid approach that combines a priori knowledge and data-driven methods to identify dietary factors that may affect kidney function in healthy and diseased subjects. Method We analysed data of 8686 adults participating in the population-based Cooperative Health Research In South Tyrol (CHRIS) study. Kidney function was multiply assessed by the estimated glomerular filtration rate (eGFR), based on serum creatinine, using the 2021 CKD-EPI equation, the urinary albumin-to-creatinine ratio (UACR), and a kidney disease questionnaire. Participants were split between those free of diagnosed kidney disease, hypertension or diabetes (Group1, n = 6133) and those diagnosed with any of the three conditions (Group2, n = 2553). Diet was assessed through the self-administered and validated GA2LEN food frequency questionnaire (FFQ). The individual consumption of each food group was converted into portions per week and adjusted for total energy intake. DPs were estimated using reduced rank regression (RRR), based on four FFQ-derived nutrient mediators (total daily dietary protein; potassium; sodium; and phosphorus intake) selected based on known effects on kidney health. Generalized cross-validation identified an optimal number of 3 DPs. Factor Loading (FL)-based scores, either as continuous or stratified into sex-stratified tertiles (T1-T2-T3), were included in multiple-adjusted linear regression models for eGFR and log(UACR). Results Group1 participants (53.4% females) were younger and presented better kidney health (median, Mdn age 39.7 years; Mdn eGFR 101.8 ml/min/1.73m2, interquartile range, IQR 91.5-112.1; Mdn UACR 5.2 mg/g, IQR 3.5-8.8) than Group2 participants (Mdn age 57.2 years; Mdn eGFR 90.8 ml/min/1.73 m2, IQR 80.4-100.3; Mdn UACR 6.5 mg/g, IQR 4.1-12). The identified DPs were (Figure 1): DP1, reflecting greater consumption of all nutrients; DP2, reflecting increased potassium and phosphorus intake and lower sodium and protein intake; and DP3, reflecting increased intake of protein and phosphorus and lower intake of potassium and sodium. The 3 DPs presented stable FLs across groups. In Group1, DP1 was negatively associated with eGFR (larger effect size in males) both as linear score and in the 3rd tertile (Figure 2); DP2 was positively associated with eGFR in males and with UACR both at low and high levels of the score, with heterogeneous effects between males and females; DP3 was positively associated with UACR overall in the 3rd tertile. In Group 2, we observed protective effects of diet on eGFR, especially at lower DP1 and DP3 levels, and at high levels of DP2 (Figure 2). Similar to Group1, also in Group2 DP2 was positively associated with UACR both at low and high level of the score, but not in males. In its 3rd tertile, DP3 was negatively associated with UACR in females. Conclusion Using RRR proved to be a valid approach to integrate a priori knowledge about nutrients in the estimation of kidney function-oriented DPs. Our results showed heterogeneous effects of the DPs across kidney outcomes, possibly reflecting specificity to kidney function or damage. In individuals affected by any kidney disease, hypertension or diabetes, the effects of DPs on eGFR reflected possible benefits of specific diets, suggesting that disease-specific dietary interventions can be a fundamental and effective approach for disease control.

#5565 USEFULNESS OF URINARY BIOCHEMISTRY IN THE FOLLOW-UP OF PATIENTS WITH CHRONIC KIDNEY DISEASE STAGES 3B-5NOD

Abstract Background and Aims Ion and protein determinations in a simple urine sample are simple and inexpensive laboratory tests that reflect well ion balance and proteinuria. However, they are underused. Evidence of their usefulness in estimating 24-hour urine biochemistry in patients with chronic kidney disease (CKD) would allow widespread use of these tests and would help to optimize therapies. It would also avoid 24-hour urine collections. To evaluate In CKD stages G3b-5noD the accuracy of equations that estimate, through simple urine sampling, creatinine, protein, and ions in 24-hour urines. Method Retrospective observational study in incident adult patients with CKD G3b-5noD from the nephrology outpatient clinic in a Madrid university hospital, with a follow-up of at least two years and with at least one simultaneous determination of biochemistry in a simple urine sample and in 24-hour urine. The 24-hour urine analyses were restricted to those that were estimated to be well collected because urinary creatinine was between 15–25 mg/kg in men and 10–20 mg/kg in women. Correlation, bias (mean differences between estimated and measured analyte), accuracy (percentage of samples estimated at 15–30 or 50% of the measured value - P15, P30, P50) and agreement by the Bland-Altman method were analyzed. CKD progression was defined by the mean annual and percentage decrease in eGFR and the renal event at follow-up as loss of more than 40% of eGFR or entry into renal replacement therapy or conservative-palliative renal treatment. Kawasaki, Tanaka and CKD-epi (Table 1) equations were used. Results The analyzed cohort was made up of 300 patients with a median follow-up of 72 (25) months. Mean eGFR was 32.8 (9.2) ml/min/1.73m2 and mean protein/creatinine ratio was 1,180 (1,740) mg/g. During follow-up 30.7% started renal replacement therapy or conservative and palliative treatment. Twenty-one patients (7%) died. The estimation of 24-hour urine creatinine by CKD-EPI equation showed excellent correlation and accuracy with measured urinary creatinine (r = 0.887; P30: 96.1% in 464 urines). Accuracy was maintained regardless of age and CKD stage. Formulas that, using single urine samples, estimate 24-hour urine elimination of Na and K correlated well with 24-hour urine measurements, but with high dispersion, especially with Na. For Na, the Tanaka and CKD-EPI formulas had the highest performance (r = 0.540; 0.532; P30: 52.6; 54.5%; bias: -14.4; -16.1 mmol, Tanaka and CKD-EPI respectively for 464 urines). These values make them useful for population studies but not for individualized analysis. For K, the Kawasaki and CKD-EPI formulas were the most suitable (r = 0.712; 0.612; P30 = 74.6; 72.4%; bias: 4.2; 5.5 mmol; Kawasaki and CKD-EPI respectively for 464 urines). These results make them useful for both population-based studies and individualized analyses. Patients with Nao < 87 mmol/day (salt-poor diet) estimated by CKD-EPI, Kawasaki or Tanaka and/or Na/K ratio < 2 directly measured had less eGFR loss at follow-up and fewer renal events. Urinary K elimination measured or estimated did not influence renal prognosis. Proteinuria measured in 24-hour urine correlated much better with proteinuria estimated by CKD-EPI in a single urine sample than with the protein/creatinine ratio (r: 0.900 vs. 0.801; mean bias: 92.2 vs. 486 mg; P30: 72.0 vs. 42.7%; CKD-EPI vs. Proto/Cro in 464 24-hour urine samples). Conclusion Urinary biochemistry in a single urine sample in patients with advanced CKD (stages G3b-5noD) is a useful tool for estimating 24-hour urine biochemistry and to identify scenarios of increased progression of renal disease.

#5209 ALGALSIDASE-BETA STABILIZES RENAL AND CARDIAC INVOLVEMENT: A FOLLOW-UP STUDY OF A BRAZILIAN FABRY DISEASE FAMILY

Abstract Background and Aims Fabry Disease (FD) is a multisystemic disorder that affects the function of major organs, such as the kidneys, the heart and the central nervous system, reducing the quality of life and leading ultimately to premature death. Early diagnosis and timely treatment are the cornerstones to change the natural history of this disorder. Method To evaluate clinical, laboratory and renal histological profiles of FD patients with a classic pathogenic variant (p.G35V), identified by targeted screening in hemodialysis patients followed by family screening, who were under enzyme replacement therapy (ERT), algalsidase-beta (0.1 mg/kg/e.o.w), for at least 48 months. Kidney biopsy was performed at baseline. Glomerular filtration rate, estimated according to the CKD-Epi equation, 24h-urinary protein and albumin were measured annually. Cardiac manifestations were evaluated by eletrocardiogram, transthoracic echocardiography (TTE) or magnetic resonance imaging (cMRI) at baseline and at the end of the study. cMRI was not performed in the index patient, due to CKD 5D, and in a pregnant female patient. Results Nine patients (age: 33.8±12.3 years) were followed-up for 80.67±5.43 months. Their main clinical manifestations were hypohidrosis (67%) gastrointestinal symptoms (56%), cornea verticilata and acroparesthesia (100%). Angiokeratomas were present only in males (100%). Five (56%) and 3 (33%) patients presented CKD G1 and G2, respectively. Only the index case presented CKD G5D. Short PR interval was observed in 44.4%. LVH was detected by TTE in 2 patients (index case and a 46-years old female); whereas based on cMRI no patient had LVH and one female had myocardial fibrosis. Patients received ERT for 70.22±12.92 months, together with adequate adjunctive therapy. eGFR and proteinuria / albuminuria remained stable during the follow-up in both sexes. Female patients presented a mean reduction of LV mass index of 9.73g/m2 (CI95%: -26.9 - 6.8). Patients who started ERT older than 30 years tended to have a higher interventricular septal thickness at the end of the follow-up (8.4 ± 2.2 vs 10.0 ± 2.7 mm; P = .08). Concerning the kidney biopsy findings, patients with higher proteinuria presented more global glomeruli sclerosis; and mild interstitial fibrosis (5%) could be detected even among young patients with normal albuminuria and eGFR. There was a significant correlation between baseline global glomeruli sclerosis and albuminuria at baseline (r=0.9; P = .01) and at the end of the follow-up (r=0.87; P = .01); and between baseline interstitial fibrosis and proteinuria at the end of the follow-up (r=0.80; P = .03). Conclusion Females with a pathogenic variant (p.G35V) for FD may develop cardiac and renal injury. FD-related renal histological changes and chronic tissue damage may be present before clinical and laboratory signs of renal dysfunction. Persistence of proteinuria during ERT might be related to the presence of interstitial fibrosis. Treatment with ERT may stabilize renal and cardiac involvement in FD. Regular monitoring and adequate pathogenetic and adjunctive treatment should be offered to FD patients of both sexes. Kidney biopsy is an important tool to evaluate pre-clinical renal involvement. Timely treatment may potentially change the natural history of the disease.

#6424 DIAGNOSTIC ACCURACY OF BONE TURNOVER MARKERS IN PATIENTS WITH VARIOUS DEGREES OF KIDNEY DYSFUNCTION AND PRIMARY OSTEOPOROSIS

Abstract Background and Aims There are limited data available on the validity of bone turnover markers (BTMs) to predict bone turnover in patients with kidney dysfunction and primary osteoporosis. Method This is a cross-sectional retrospective study of patients with primary osteoporosis and eGFR<90 ml/min/1.73 m2 who had bone biopsy for clinical purposes for a time period of 8 years. CKD-EPI equation 2021 was used to calculate eGFR based on the mean serum creatinine readings. Bone biopsy samples were evaluated qualitatively using KDIGO TMV classification. Routine laboratory data were collected in addition to alkaline phosphatase, iPTH, cyclase activating (CAP) PTH, osteocalcin, bone specific alkaline phosphatase (BSAP), and N-telopeptide collagen (NTX). Results Study included 156 patients with mean age of 64.7 years. The majority of patients were females (93.6%). The mean BMI was 26.2 kg/m2. The mean eGFR was 70 ml/min with 78% of patients had eGFR from 60-90 ml/min/1.73 m2. CKD stage III was found in 19%, and 3% of patients had CKD stage IV. HTN was found in 47%, history of kidney stones in 9%, and fragility fractures in 77%. Bisphosphonates were the most used pre-biopsy bone specific medication (66%). Teriparatide was used in 10.9% and SERM was used in 7.7% of patients, while 31.4% of patients did not receive any bone anti-resorptive or anabolic medication “treatment naiive”. Bone cortical thickness and cancellous volume were low in 94.2%, while high bone turnover (HBT) was found in 42.9% and low bone turnover (LBT) in 57.1%. Mineralization was defective only in 9.6%, while osteoid thickness was increased in 5.8%. Figure 1 shows the distribution of bone turnover among study group. Baseline characteristics and routine laboratory data were not different between HBT and LBT. PTH, especially PTH CAP, and alkaline phosphatase tended to be higher in HBT but did not reach statistical significance. While BTMs (osteocalcin, BSAP and NTX) were significantly higher in HBT (Table 1). Using ROC curve analysis, the area under the curve (AUC) for BSAP, NTX and osteocalcin were 0.605, 0.660, 0.642, respectively. Combining the NTX with either BSAP or osteocalcin did not result in increasing the AUC. This was also the same when the three of them were combined. BTMs were able to discriminate bone turnover status only among patients with eGFR≥60 ml/min/1.73 m2 (Table 2). Conclusion Low bone turnover was found in 43% in treatment naïve patients with primary osteoporosis, with a higher prevalence among patients with eGFR≥60. In the study group, PTH and total alkaline phosphatase were not able to discriminate LBT from HBT, while BTMs showed a modest ability to discriminate the turnover status only among patients with eGFR≥60.

Performance of Nuclear Magnetic Resonance-Based Estimated Glomerular Filtration Rate in a Real-World Setting

An accurate estimate of glomerular filtration rate (eGFR) is essential for proper clinical management, especially in patients with kidney dysfunction. This prospective observational study evaluated the real-world performance of the nuclear magnetic resonance (NMR)-based GFRNMR equation, which combines creatinine, cystatin C, valine, and myo-inositol with age and sex. We compared GFRNMR performance to that of the 2021 CKD-EPI creatinine and creatinine-cystatin C equations (CKD-EPI2021Cr and CKD-EPI2021CrCys), using 115 fresh routine samples of patients scheduled for urinary iothalamate clearance measurement (mGFR). Median bias to mGFR of the three eGFR equations was comparably low, ranging from 0.4 to 2.0 mL/min/1.73 m2. GFRNMR outperformed the 2021 CKD-EPI equations in terms of precision (interquartile range to mGFR of 10.5 vs. 17.9 mL/min/1.73 m2 for GFRNMR vs. CKD-EPI2021CrCys; p = 0.01) and accuracy (P15, P20, and P30 of 66.1% vs. 48.7% [p = 0.007], 80.0% vs. 60.0% [p < 0.001] and 95.7% vs. 86.1% [p = 0.006], respectively, for GFRNMR vs. CKD-EPI2021CrCys). Clinical parameters such as etiology, comorbidities, or medications did not significantly alter the performance of the three eGFR equations. Altogether, this study confirmed the utility of GFRNMR for accurate GFR estimation, and its potential value in routine clinical practice for improved medical care.

Concordancia entre las ecuaciones de estimación del filtrado glomerular y el aclaramiento de creatinina en orina de 4 horas en pacientes críticos con trauma grave

Background and objectiveThere is a growing body of evidence that the equations used to estimate the glomerular filtration rate (GFR) are not suitable in critically ill patients, a population whose GFR fluctuates continuously. Glomerular filtration is usually estimated by measuring urine creatinine clearance (CrCl) at various time points. The aim of our study was to evaluate the performance of the most widely used GFR calculators in the subpopulation of critically ill patients admitted for severe trauma, and to compare the results against determinations of CrCl in urine collected over a 4-hour period (4h-CrCl). Material and methodsObservational study in patients hospitalized for severe trauma. We measured the 4h-CrCl and estimated GFR using the Cockcroft-Gault, modified Jelliffe, MDRD, t-MDRD, and CKD-EPI equations, adjusting the results for body surface area (BSA) (ml/min/1.73m2). Data were analysed using R version 4.0.4. ResultsA total of 85 patients were included. Median age was 51years, and 68 were men (78.82%). The mean BSA-adjusted 4h-CrCl (4h-ClCr/1.73m2) was 84.5ml/min/1.73m2. We found that GFR estimated using the t-MDRD equation correlated significantly with 4h-CrCl/1.73m2. The Cockcroft-Gault equation correlated significantly with 4h-CrCl/1.73m2 when GFR was greater than 130ml/min/m2. ConclusionsIn ICU patients, glomerular filtration can be reliably estimated by determining urine CrCl, but GFR calculators are not accurate in this population.