Chronic Kidney Disease Epidemiology Collaboration Study Research Articles

Changes in renal blood flow after surgically induced weight loss: can bariatric surgery halt the progression of chronic kidney disease?

BackgroundWe previously demonstrated how kidney injury in patients with morbid obesity can be reversed by bariatric surgery (BaS). Objective(s)Based on previous experience, we hypothesize patients’ potentially reversible kidney injury might be secondary to reduction in renal blood flow (RBF), which improves following BaS. SettingAcademic Hospital. MethodsWe conducted a retrospective analysis of patients who underwent BaS at our institution from 2002 to 2019. We identified patients with chronic kidney disease (CKD) using the estimated glomerular filtration rate (eGFR) from the CKD Epidemiology Collaboration Study (CKD-EPI) classification system. We used the BUN/Creatinine (Cr) ratio pre- and postoperatively to determine a prerenal (decreased RBF) versus intrinsic component as the responsible cause of CKD in this patient population. Decreased RBF was defined as BUN/Cr > 20 preoperatively. ResultsOur analysis included n = 2924 patients, of which 11% (n = 325) presented decreased RBF. From our original sample, only n = 228 patients had the complete data necessary to assess both eGFR and RBF (BUN/Cr). Patients with baseline CKD stage 2 demonstrated preoperative BUN/Cr 20.85 ± 10.23 decreasing to 14.99 ± 9.10 at 12-month follow-up (P < .01). Patients with baseline CKD stage 3 presented with preoperative BUN/Cr 23.88 ± 8.75; after 12-month follow-up, BUN/Cr ratio decreased to 16.38 ± 9.27 (P < .01). Patients with CKD stage 4 and ESRD (eGFR < 30) did not demonstrate a difference for pre- and postoperative BUN/Cr 21.71 ± 9.28 and 19.21 ± 14.58, respectively. Conclusion(s)According to our findings, patients with CKD stages 1–3 present improvement of their kidney function after BaS. This amelioration could be secondary to improvement of the RBF, an unstudied reversible mechanism of kidney injury in the bariatric population.

Blood Urea Nitrogen Levels to Verify Estimated Glomerular Filtration Rate, as Derived from 2 Commonly Used Equations.

A blood urea nitrogen to creatinine ratio (BCR) of 20 or greater indicates various physiological conditions. Whether glomerular filtration rate (GFR) estimates obtained using the Modification of Diet in Renal Disease (MDRD) study equation and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) study equations are affected by a high BCR remains unknown. Patients who underwent urine creatinine clearance (CrCl) and serum blood urea nitrogen (BUN) and creatinine assessments on the same day were enrolled in our study. Those with BCR of 20 or greater and less than 20 were categorized into high- and low-BCR groups. The concordance on diagnosing chronic kidney disease (CKD) stages by using urine CrCl level and serum GFR estimates was assessed. More disagreement in CKD stage diagnosis was observed in the high-BCR group (weighted κ = 0.600 and 0.541 for the MDRD and CKD-EPI study equations, respectively) than in the low-BCR group (weighted κ = 0.816 and 0.758, respectively). A BCR of 20 or greater caused misestimation of the CKD stage. GFR estimates for patients with high BCR should be interpreted cautiously.

Comparison of the MDRD Study and the CKD-EPI Study equations in evaluating trends of estimated kidney function at population level: findings from the National FINRISK Study

There are no data comparing the Modification of Diet in Renal Disease (MDRD) Study and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) Study equations in the evaluation of time-dependent trend of estimated glomerular filtration rate (eGFR) in the general population. Changes in eGFR and in the association of eGFR with kidney disease and cardiovascular disease (CVD) risk factors across age groups were estimated in two independent cross-sectional population surveys in Finland in 2002 and 2007 with 11 277 study participants, aged 25-74 years, using both the MDRD and the CKD-EPI equations. A trend towards decreasing eGFRs between the study years was observed using both equations, but the trend was more substantial when using the MDRD equation. The MDRD equation yielded lower estimates of eGFR than the CKD-EPI equation, with small mean difference between the equations at low eGFR level but substantial at the level of only mildly decreased or near-normal to normal kidney function. Decrease of eGFR was associated with an increase in CKD and CVD risk factors. However, an increase of risk factors was not observed among those who had mildly decreased eGFR by only the MDRD equation but not by the CKD-EPI equation. In comparison with the CKD-EPI equation, the MDRD equation augmented the trend of increasing prevalence of CKD, showed a weaker association with risk factors and tended to assign impaired renal function to individuals without an excess of cardiovascular risk factors.

Long-Term Outcomes of Renal Function in Patients with TTP Associated with Severe ADAMTS13 Deficiency

Abstract▪2215▪This icon denotes a clinically relevant abstract Introduction:Among survivors of TTP associated with severe ADAMTS13 deficiency, long-term outcomes other than relapse are not well documented. The recent report of persistent minor neurocognitive abnormalities attributed to subcortical microvascular thrombosis (Transfusion 2009;49:1092) suggested that other organs may also be affected by subclinical abnormalities. Therefore we documented renal function in patients in the Oklahoma TTP-HUS Registry who survived acute episodes of TTP associated with severe ADAMTS13 deficiency (activity <10%). Methods:ADAMTS13 activity has been measured in 299 of 321 (93%) patients, 1995–2010. Glomerular filtration rate (GFR) was calculated by the Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equation (Ann Int Med 2009;150:604). Urine protein was measured by dipstick. Patient GFRs were compared to GFRs for the US population using data from the National Health and Nutrition Examination Survey (NHANES), 1998–2006, that had been analyzed in the CKD-EPI study. Results:68 of 299 (23%) patients from the Oklahoma TTP-HUS Registry had severe ADAMTS13 deficiency. Fifty-five of the 68 (81%) patients with severe ADAMTS13 deficiency survived their initial episode of TTP. Among the 55 survivors, 48 (87%) have had ≥1 year of follow-up (median, 6.4 years; range, 1.0 – 14.9 years). The 7 patients whose follow-up was less than 1 year included 3 patients whose initial episode was within the past year; 2 with systemic lupus erythematosus who died within one year; 1 who relapsed and died at one year; 1 lost to follow-up. Sixteen (33%) of the 48 patients had 1–4 relapses. None of the 48 patients developed end stage renal disease and none developed severe chronic kidney disease (GFR <30 ml/min/1.73m2). Three of the 48 patients had chronic kidney disease with moderately decreased GFR (GFR 30–59 ml/min/1.73m2); two of these patients had hypertension and one had hypertension and diabetes prior to their initial episodes of TTP. The median GFR was 97 ml/min/1.73m2 (range, 30 – 139 ml/min/1.73m2). The GFR for the ADAMTS13 deficient TTP patients was not different from the GFR of the U.S. population (p=0.289) (Figure 1). Urine protein was measured on 34 patients (median follow-up, 6.7 years; range, 1.2–14.9 years): 32 (94%) were negative; 2 (6%) were trace, equivalent to <30 μg albumin/mg creatinine. [Display omitted] Conclusion:Renal function of TTP patients with severe ADAMTS13 deficiency who had been followed for a median of 6.4 years following recovery from their initial episode was not different from the US population. Disclosures:No relevant conflicts of interest to declare.