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Renal Biomarkers for Assessment of Kidney Function in Renal Transplant Recipients: How do They Compare?
NKF 2012 Spring Clinical Meetings Abstracts
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47 TRENDS IN RENAL ULTRASOUND IMAGING IN CKD PATIENTS PRE AND POST KDOQI GUIDELINES IN THE NATIONAL VETERANS HEALTH AFFAIRS (VA) SYSTEM. Nadia Chaudhri and Stephen Seliger, Baltimore VAMC, Baltimore, Maryland. K/DOQI CKD Guidelines from 2002 recommend imaging studies in the initial evaluation of pts with CKD. We performed an observational longitudinal study of active outpatients with incident CKD, defined as eGFR<60, from 20022006 in the national VA system to determine the utilization of renal ultrasound(US) imaging (N=127,155). Imaging rates were estimated by year and eGFR category; logistic regression was used to identify factors associated with renal imaging. Adjusting for demographics, co-morbidity, and eGFR, greater utilization of renal US was related to nephrology care(OR:15.2), Black race(OR:1.5), Diabetes(OR:1.3) prior stroke(OR:1.51), and peripheral arterial disease(OR:1.6), but not CAD(OR:1.1). Overall, frequency of renal US was low (12%), with greater utilization in pts with lower initial eGFR. There was no meaningful change in utilization after release of the K/DOQI guidelines.
RENAL BIOMARKERS FOR ASSESSMENT OF KIDNEY FUNCTION IN RENAL TRANSPLANT RECIPIENTS: HOW DO THEY COMPARE? Ahmed Chaaban1, Samra Abouchacra1, Yousef Boobes1, Raafat Hakim1, Nicole Gebran1, Hanan El-Jack1, Faiz Rashid1, Amna Muhairi1, Nico Negelkerke2 1 Tawam Hospital, 2Faculty of Medicine &Health Sciences; UAE. Accurate assessment of renal function is crucial given its strong association with morbidity and mortality. However, gold standard measures are cumbersome and serum creatinine itself is an insensitive predictor; especially in renal transplant recipients. Though GFR estimating formulae have been relied upon, they do have their own limitations. Nevertheless renal biomarkers such as NGAL (Neutrophil Gelatinase Associated Lipocalin) and Cystatin C are now emerging as potentially useful indicators of GFR. We aimed to evaluate the diagnostic performance of NGAL vs Cystatin C and eGFR using CKD-Epi, MDRD and Cystatin C in renal transplant recipients. 72 patients were evaluated (M:F 44:28), mean age 44.58 ±14.25 yrs, 54.43± 42.92 months post transplant with mean serum creatinine 105.94± 51.77 µmol/l. Mean NGAL was 91.32±71.73 ng/ml with Cystatin C levels 1.27 ± 0.65 mg/l corresponding to eGFRCKD Epi 76.18 ± 23.45, GFRMDRD 69.29 ± 21.36 and eGFRCystatinc 60.14 ± 24.66 ml/min/1.73m2. Using univariate analysis, there was significant correlation between NGAL and serum creatinine (r=0.77), Cystatin C (r=0.76) and eGFR (rCystatin C= 0.79, rCKDEpi = 0.59, r MDRD =0.42 ). These parameters including age were also strong predictors of serum NGAL levels by multiple regressions. However, performance of NGAL based on Receiver Operating Characteristic (ROC) curve was inferior to that of the reference tests. It appears that in renal transplant recipients, NGAL correlates well with Cystatin C and eGFR; most strongly with Cystatin- based formula. Though this suggests potential for the use of NGAL as a screening test, its weaker diagnostic performance on ROC raises some concern with its clinical usefulness. Larger studies are needed to explore this further.
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48 A CASE OF GITELMAN SYNDROME WITH A NOVEL MUTATION Sanjay Chaudhary, Qi Qian. Mayo Clinic, Rochester, MN Gitelman’s syndrome (GS) is a rare, autosomal recessive, salt-losing tubulopathy caused by mutations in the SLC12A3 gene, which encodes the thiazide-sensitive NaCl cotransporter resulting in hypokalemic metabolic alkalosis, hypomagnesaemia, and hypocalciuria. A 19-year-old Caucasian male presented for evaluation of recurrent muscular cramps on exertion since about 12-13 years of age. They had been severe enough to warrant him being taken to the emergency room on multiple occasions and evaluation revealed potassium to be as low as 2.6 mEq/L. He had been on potassium chloride supplementation 240 mEq daily. On presentation to our institution, his BP was 107/62 mmHg. His serum chemistry revealed potassium 3.2 mEq/L, bicarbonate 31 mmol/L, calcium 10.2 mg/dL, and magnesium 1.5 mg/dL. His plasma renin activity was 15 ng/ml/hour and aldosterone 63 ng/dL. His 24-hour urine calcium was 66 mg and calcium/creatinine ratio 0.04. Mutation analysis for Gitelman syndrome showed a heterozygous mutation in exon 4, c.533C>T that is predicted to result in abnormal protein (p.Ser178Leu) and a heterozygous variant in exon 6, c.815T>C on the other allele that is of unknown significance. The patient was effectively treated with potassium 240 mEq/day, amiloride 10 mg/day, and magnesium oxide 1600 mg/day. To date, >180 mutations in SLC12A3 have been reported. We describe a patient who exhibits Gitelman phenotype with a novel double heterozygous variant of SLC12A3 that has not been previously known to be pathogenic.
A26
In summary, renal imaging for outpatients with incident CKD is uncommon in the national VA system, especially among those without nephrology care, with no increase in utilization in response to K/DOQI guidelines.
FISTULA FIRST: JOURNEY FROM LAST TO FIRST A QUALITY IMPROVEMENT (QI) PROJECT Kashif Chaudhry, D Abu-Hamdan, C Ohs, K Crossley, J Chacko. John D Dingell VAMC, Detroit, MI, USA. In March 2005, the Fistula First initiative (FFI) was launched to increase the rate of AVF to 66% in US ESRD population. The superiority of Arterio-Venous Fistula (AVF) is well established, due to longevity of the access, very low risk of infection and sepsis, fewer hospitalizations and hence low morbidity, mortality and health care cost. The challenges of achieving this goal at an inner city center like Detroit were met through a coordinated effort between nephrology, vascular surgery and nursing staff. We are reporting a QI project, done at VAMC in Detroit. Our QI achieved an increase in AVF prevalence from < 40% to >70% and a decrease in venous catheters prevalence from 40% to < 15%. We are on target to reach 80% AVF access in our patient population and a decrease in catheter rate to 10% in 2011: far exceeding the national average. As a predictable result, the rate of infections and sepsis calculated as number of infections/HD procedures/1000 device days went down from 3.12 in 2009 to 1.44 in 2010 to 0.56 in 2011. AVF prevalence comparison: July 2010-June2011
The co-ordinated efforts of the surgeon, the nephrologist, the support staff and patient education all played pivotal role not only in achieving the FFI target of 66% but exceeding it to 70% and higher.
Am J Kidney Dis. 2012;59(4):A1-A92
45
47 TRENDS IN RENAL ULTRASOUND IMAGING IN CKD PATIENTS PRE AND POST KDOQI GUIDELINES IN THE NATIONAL VETERANS HEALTH AFFAIRS (VA) SYSTEM. Nadia Chaudhri and Stephen Seliger, Baltimore VAMC, Baltimore, Maryland. K/DOQI CKD Guidelines from 2002 recommend imaging studies in the initial evaluation of pts with CKD. We performed an observational longitudinal study of active outpatients with incident CKD, defined as eGFR<60, from 20022006 in the national VA system to determine the utilization of renal ultrasound(US) imaging (N=127,155). Imaging rates were estimated by year and eGFR category; logistic regression was used to identify factors associated with renal imaging. Adjusting for demographics, co-morbidity, and eGFR, greater utilization of renal US was related to nephrology care(OR:15.2), Black race(OR:1.5), Diabetes(OR:1.3) prior stroke(OR:1.51), and peripheral arterial disease(OR:1.6), but not CAD(OR:1.1). Overall, frequency of renal US was low (12%), with greater utilization in pts with lower initial eGFR. There was no meaningful change in utilization after release of the K/DOQI guidelines.
RENAL BIOMARKERS FOR ASSESSMENT OF KIDNEY FUNCTION IN RENAL TRANSPLANT RECIPIENTS: HOW DO THEY COMPARE? Ahmed Chaaban1, Samra Abouchacra1, Yousef Boobes1, Raafat Hakim1, Nicole Gebran1, Hanan El-Jack1, Faiz Rashid1, Amna Muhairi1, Nico Negelkerke2 1 Tawam Hospital, 2Faculty of Medicine &Health Sciences; UAE. Accurate assessment of renal function is crucial given its strong association with morbidity and mortality. However, gold standard measures are cumbersome and serum creatinine itself is an insensitive predictor; especially in renal transplant recipients. Though GFR estimating formulae have been relied upon, they do have their own limitations. Nevertheless renal biomarkers such as NGAL (Neutrophil Gelatinase Associated Lipocalin) and Cystatin C are now emerging as potentially useful indicators of GFR. We aimed to evaluate the diagnostic performance of NGAL vs Cystatin C and eGFR using CKD-Epi, MDRD and Cystatin C in renal transplant recipients. 72 patients were evaluated (M:F 44:28), mean age 44.58 ±14.25 yrs, 54.43± 42.92 months post transplant with mean serum creatinine 105.94± 51.77 µmol/l. Mean NGAL was 91.32±71.73 ng/ml with Cystatin C levels 1.27 ± 0.65 mg/l corresponding to eGFRCKD Epi 76.18 ± 23.45, GFRMDRD 69.29 ± 21.36 and eGFRCystatinc 60.14 ± 24.66 ml/min/1.73m2. Using univariate analysis, there was significant correlation between NGAL and serum creatinine (r=0.77), Cystatin C (r=0.76) and eGFR (rCystatin C= 0.79, rCKDEpi = 0.59, r MDRD =0.42 ). These parameters including age were also strong predictors of serum NGAL levels by multiple regressions. However, performance of NGAL based on Receiver Operating Characteristic (ROC) curve was inferior to that of the reference tests. It appears that in renal transplant recipients, NGAL correlates well with Cystatin C and eGFR; most strongly with Cystatin- based formula. Though this suggests potential for the use of NGAL as a screening test, its weaker diagnostic performance on ROC raises some concern with its clinical usefulness. Larger studies are needed to explore this further.
46
48 A CASE OF GITELMAN SYNDROME WITH A NOVEL MUTATION Sanjay Chaudhary, Qi Qian. Mayo Clinic, Rochester, MN Gitelman’s syndrome (GS) is a rare, autosomal recessive, salt-losing tubulopathy caused by mutations in the SLC12A3 gene, which encodes the thiazide-sensitive NaCl cotransporter resulting in hypokalemic metabolic alkalosis, hypomagnesaemia, and hypocalciuria. A 19-year-old Caucasian male presented for evaluation of recurrent muscular cramps on exertion since about 12-13 years of age. They had been severe enough to warrant him being taken to the emergency room on multiple occasions and evaluation revealed potassium to be as low as 2.6 mEq/L. He had been on potassium chloride supplementation 240 mEq daily. On presentation to our institution, his BP was 107/62 mmHg. His serum chemistry revealed potassium 3.2 mEq/L, bicarbonate 31 mmol/L, calcium 10.2 mg/dL, and magnesium 1.5 mg/dL. His plasma renin activity was 15 ng/ml/hour and aldosterone 63 ng/dL. His 24-hour urine calcium was 66 mg and calcium/creatinine ratio 0.04. Mutation analysis for Gitelman syndrome showed a heterozygous mutation in exon 4, c.533C>T that is predicted to result in abnormal protein (p.Ser178Leu) and a heterozygous variant in exon 6, c.815T>C on the other allele that is of unknown significance. The patient was effectively treated with potassium 240 mEq/day, amiloride 10 mg/day, and magnesium oxide 1600 mg/day. To date, >180 mutations in SLC12A3 have been reported. We describe a patient who exhibits Gitelman phenotype with a novel double heterozygous variant of SLC12A3 that has not been previously known to be pathogenic.
A26
In summary, renal imaging for outpatients with incident CKD is uncommon in the national VA system, especially among those without nephrology care, with no increase in utilization in response to K/DOQI guidelines.
FISTULA FIRST: JOURNEY FROM LAST TO FIRST A QUALITY IMPROVEMENT (QI) PROJECT Kashif Chaudhry, D Abu-Hamdan, C Ohs, K Crossley, J Chacko. John D Dingell VAMC, Detroit, MI, USA. In March 2005, the Fistula First initiative (FFI) was launched to increase the rate of AVF to 66% in US ESRD population. The superiority of Arterio-Venous Fistula (AVF) is well established, due to longevity of the access, very low risk of infection and sepsis, fewer hospitalizations and hence low morbidity, mortality and health care cost. The challenges of achieving this goal at an inner city center like Detroit were met through a coordinated effort between nephrology, vascular surgery and nursing staff. We are reporting a QI project, done at VAMC in Detroit. Our QI achieved an increase in AVF prevalence from < 40% to >70% and a decrease in venous catheters prevalence from 40% to < 15%. We are on target to reach 80% AVF access in our patient population and a decrease in catheter rate to 10% in 2011: far exceeding the national average. As a predictable result, the rate of infections and sepsis calculated as number of infections/HD procedures/1000 device days went down from 3.12 in 2009 to 1.44 in 2010 to 0.56 in 2011. AVF prevalence comparison: July 2010-June2011
The co-ordinated efforts of the surgeon, the nephrologist, the support staff and patient education all played pivotal role not only in achieving the FFI target of 66% but exceeding it to 70% and higher.
Am J Kidney Dis. 2012;59(4):A1-A92