- Email: [email protected]
Re: Long-Term Renal Function Outcomes after Radical Cystectomy
LETTERS TO THE EDITOR/ERRATA
1066
in unusual or challenging situations. However, these situations should be determined on a case by case basis after review by an experienced radiologist. The 2004 consensus on genitourinary trauma article states that hemodynamically stable children with blunt trauma should undergo radiographic evaluation if they have gross hematuria or more than 50 red blood cells per high power field on microscopic urinalysis.1 According to the current study, “Generally, children can be imaged using the same criteria as adults.” However, this statement does not take into account the subsequent observation that children “often do not exhibit hypotension as adults do.” Did the panel find that children with more than 50 red blood cells per high power field but no evidence of hypotension meet or do not meet criteria for imaging? Respectfully, Joel A. Gross, Claire K. Sandstrom and Jeffrey D. Robinson Department of Radiology, Section of Emergency Radiology University of Washington School of Medicine Harborview Medical Center Seattle, Washington
1. Santucci RA, Wessells H, Bartsch G et al: Evaluation and management of renal injuries: consensus statement of the renal trauma subcommittee. BJU Int 2004; 93: 937.
Re: Long-Term Renal Function Outcomes after Radical Cystectomy M. S. Eisenberg, R. H. Thompson, I. Frank, S. P. Kim, K. J. Cotter, M. K. Tollefson, D. Kaushik, P. Thapa, R. Tarrell and S. A. Boorjian J Urol 2014; 191: 619e625.
To the Editor: This study is of major interest because it evaluates long-term renal function variations after radical cystectomy and urinary diversion. Indeed, the natural history and longterm followup of renal function decline in patients treated with radical cystectomy have been poorly reported.1 However, urologists need to be aware of renal function variations that may be observed after such major surgical procedures, including radical cystectomy. There is no current consensus on the mode of upper tract surveillance after radical cystectomy. In this study Eisenberg et al assessed renal function variations using an estimated glomerular filtration rate (GFR) equation. Therefore, some comments should be made regarding the evaluation of renal function in this specific group of patients with ileum interposed on the urinary tract. Although the gold standard to assess renal function is isotopic GFR measurement,2 equations estimating GFR are commonly used in routine clinical practice. Thus, the authors chose to monitor renal function using the recently published CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation.3 New findings from the Chronic Kidney Disease Prognosis Consortium showed that the CKD-EPI equation assesses renal function more accurately than the MDRD (Modification of Diet in Renal Disease) GFR equation, with the best prediction of long-term patient outcomes and the least bias covering a large estimated GFR range in a variety of populations.4,5 However, to our knowledge the correlation between the CKD-EPI equation and isotopic GFR in patients who have undergone urinary tract reconstruction or diversion has not been assessed. Recently we prospectively evaluated renal function variations after radical cystectomy and orthotopic ileal neobladder.6 We found that the MDRD equation overestimated isotopic GFR clearance preoperatively and postoperatively. Because early detection of renal function impairment is critical to prevent irreversible kidney damage, accurate monitoring of renal function after radical cystectomy is crucial. Therefore, caution should be used regarding the equations estimating renal function until a validated and reliable equation is available in this specific group of patients. A second issue that should be addressed concerns the proper definition of renal function decrease. Eisenberg et al determined that a reduction greater than 10 ml/minute/1.73 m2 from baseline during followup could be categorized as renal function decline. Arguably methods to define renal function deterioration are heterogeneous across studies.7 In addition, the threshold
LETTERS TO THE EDITOR/ERRATA
1067
of estimated GFR loss in the general population through time remains unclear. Recently a large longitudinal study provided new data on the estimated GFR decline with age, suggesting that the natural rate of decrease yearly is up to 1.27 ml/minute/1.73 m2 for healthy subjects older than 50 years, and 1.44 ml/minute/1.73 m2 in those with comorbidities such as hypertension and diabetes.8 Therefore, urologists need to integrate all of these parameters to assess more accurately renal function decline in patients, notably in those with multiple comorbidities. In conclusion, accurate estimation of GFR decline with time is of paramount importance in patients with ileum interposed on the urinary tract, who remain at lifelong risk for chronic kidney disease. We believe that monitoring renal function using isotopic GFR measurement should be conducted at regular intervals to properly assess GFR variations in these patients. Respectfully, Mathieu Rouanne and Thierry Lebret Department of Urology Hoˆpital Foch UFR des Sciences de la Sante Versailles-Saint-Quentin-en-Yvelines Universite France
and Marie Courbebaisse Department of Renal Physiology en Georges Pompidou Hoˆpital Europe de Medecine Faculte Paris-Descartes Universite France e-mail: [email protected]
1. Jin XD, Roethlisberger S, Burkhard FC et al: Long-term renal function after urinary diversion by ileal conduit or orthotopic ileal bladder substitution. Eur Urol 2012; 61: 491. 2. Fleming JS, Zivanovic MA, Blake GM et al: Guidelines for the measurement of glomerular filtration rate using plasma sampling. Nucl Med Commun 2004; 25: 759. 3. Matsushita K, Mahmoodi BK, Woodward M et al: Comparison of risk prediction using the CKD-EPI equation and the MDRD study equation for estimated glomerular filtration rate. JAMA 2012; 307: 1941. 4. Inker LA and Levey AS: Pro: Estimating GFR using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2009 creatinine equation: the time for change is now. Nephrol Dial Transplant 2013; 28: 1390.
5. Lane BR, Demirjian S, Weight CJ et al: Performance of the chronic kidney disease-epidemiology study equations for estimating glomerular filtration rate before and after nephrectomy. J Urol 2010; 183: 896. 6. Rouanne M, Neuzillet Y, Eladari D et al: Are we evaluating properly the renal function with the Modification of Diet in Renal Disease (MDRD) in patients with orthotopic ileal neobladder? J Urol, suppl., 2013; 189: e580, abstract 1416. 7. Harraz AM, Mosbah A, El-Assmy A et al: Renal function evaluation in patients undergoing orthotopic bladder substitution: a systematic review of literature. BJU Int 2014; 114: 484. 8. Cohen E, Nardi Y, Krause I et al: A longitudinal assessment of the natural rate of decline in renal function with age. J Nephrol 2014; Epub ahead of print.
Re: Tissue Engineered Cystoplasty Augmentation for Treatment of Neurogenic Bladder Using Small Intestinal Submucosa: An Exploratory Study F. Zhang and L. Liao J Urol 2014; 192: 544e551.
To the Editor: The authors are to be congratulated for furthering the discussion of the role of urothelial line bladder augmentation as a solution to the problems of inclusion of bowel mucosa in bladder expansion technology. However, previous work not referenced by the authors has strongly suggested that an autoaugmented bladder that is then covered by demusosalized gastric
1066
in unusual or challenging situations. However, these situations should be determined on a case by case basis after review by an experienced radiologist. The 2004 consensus on genitourinary trauma article states that hemodynamically stable children with blunt trauma should undergo radiographic evaluation if they have gross hematuria or more than 50 red blood cells per high power field on microscopic urinalysis.1 According to the current study, “Generally, children can be imaged using the same criteria as adults.” However, this statement does not take into account the subsequent observation that children “often do not exhibit hypotension as adults do.” Did the panel find that children with more than 50 red blood cells per high power field but no evidence of hypotension meet or do not meet criteria for imaging? Respectfully, Joel A. Gross, Claire K. Sandstrom and Jeffrey D. Robinson Department of Radiology, Section of Emergency Radiology University of Washington School of Medicine Harborview Medical Center Seattle, Washington
1. Santucci RA, Wessells H, Bartsch G et al: Evaluation and management of renal injuries: consensus statement of the renal trauma subcommittee. BJU Int 2004; 93: 937.
Re: Long-Term Renal Function Outcomes after Radical Cystectomy M. S. Eisenberg, R. H. Thompson, I. Frank, S. P. Kim, K. J. Cotter, M. K. Tollefson, D. Kaushik, P. Thapa, R. Tarrell and S. A. Boorjian J Urol 2014; 191: 619e625.
To the Editor: This study is of major interest because it evaluates long-term renal function variations after radical cystectomy and urinary diversion. Indeed, the natural history and longterm followup of renal function decline in patients treated with radical cystectomy have been poorly reported.1 However, urologists need to be aware of renal function variations that may be observed after such major surgical procedures, including radical cystectomy. There is no current consensus on the mode of upper tract surveillance after radical cystectomy. In this study Eisenberg et al assessed renal function variations using an estimated glomerular filtration rate (GFR) equation. Therefore, some comments should be made regarding the evaluation of renal function in this specific group of patients with ileum interposed on the urinary tract. Although the gold standard to assess renal function is isotopic GFR measurement,2 equations estimating GFR are commonly used in routine clinical practice. Thus, the authors chose to monitor renal function using the recently published CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation.3 New findings from the Chronic Kidney Disease Prognosis Consortium showed that the CKD-EPI equation assesses renal function more accurately than the MDRD (Modification of Diet in Renal Disease) GFR equation, with the best prediction of long-term patient outcomes and the least bias covering a large estimated GFR range in a variety of populations.4,5 However, to our knowledge the correlation between the CKD-EPI equation and isotopic GFR in patients who have undergone urinary tract reconstruction or diversion has not been assessed. Recently we prospectively evaluated renal function variations after radical cystectomy and orthotopic ileal neobladder.6 We found that the MDRD equation overestimated isotopic GFR clearance preoperatively and postoperatively. Because early detection of renal function impairment is critical to prevent irreversible kidney damage, accurate monitoring of renal function after radical cystectomy is crucial. Therefore, caution should be used regarding the equations estimating renal function until a validated and reliable equation is available in this specific group of patients. A second issue that should be addressed concerns the proper definition of renal function decrease. Eisenberg et al determined that a reduction greater than 10 ml/minute/1.73 m2 from baseline during followup could be categorized as renal function decline. Arguably methods to define renal function deterioration are heterogeneous across studies.7 In addition, the threshold
LETTERS TO THE EDITOR/ERRATA
1067
of estimated GFR loss in the general population through time remains unclear. Recently a large longitudinal study provided new data on the estimated GFR decline with age, suggesting that the natural rate of decrease yearly is up to 1.27 ml/minute/1.73 m2 for healthy subjects older than 50 years, and 1.44 ml/minute/1.73 m2 in those with comorbidities such as hypertension and diabetes.8 Therefore, urologists need to integrate all of these parameters to assess more accurately renal function decline in patients, notably in those with multiple comorbidities. In conclusion, accurate estimation of GFR decline with time is of paramount importance in patients with ileum interposed on the urinary tract, who remain at lifelong risk for chronic kidney disease. We believe that monitoring renal function using isotopic GFR measurement should be conducted at regular intervals to properly assess GFR variations in these patients. Respectfully, Mathieu Rouanne and Thierry Lebret Department of Urology Hoˆpital Foch UFR des Sciences de la Sante Versailles-Saint-Quentin-en-Yvelines Universite France
and Marie Courbebaisse Department of Renal Physiology en Georges Pompidou Hoˆpital Europe de Medecine Faculte Paris-Descartes Universite France e-mail: [email protected]
1. Jin XD, Roethlisberger S, Burkhard FC et al: Long-term renal function after urinary diversion by ileal conduit or orthotopic ileal bladder substitution. Eur Urol 2012; 61: 491. 2. Fleming JS, Zivanovic MA, Blake GM et al: Guidelines for the measurement of glomerular filtration rate using plasma sampling. Nucl Med Commun 2004; 25: 759. 3. Matsushita K, Mahmoodi BK, Woodward M et al: Comparison of risk prediction using the CKD-EPI equation and the MDRD study equation for estimated glomerular filtration rate. JAMA 2012; 307: 1941. 4. Inker LA and Levey AS: Pro: Estimating GFR using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2009 creatinine equation: the time for change is now. Nephrol Dial Transplant 2013; 28: 1390.
5. Lane BR, Demirjian S, Weight CJ et al: Performance of the chronic kidney disease-epidemiology study equations for estimating glomerular filtration rate before and after nephrectomy. J Urol 2010; 183: 896. 6. Rouanne M, Neuzillet Y, Eladari D et al: Are we evaluating properly the renal function with the Modification of Diet in Renal Disease (MDRD) in patients with orthotopic ileal neobladder? J Urol, suppl., 2013; 189: e580, abstract 1416. 7. Harraz AM, Mosbah A, El-Assmy A et al: Renal function evaluation in patients undergoing orthotopic bladder substitution: a systematic review of literature. BJU Int 2014; 114: 484. 8. Cohen E, Nardi Y, Krause I et al: A longitudinal assessment of the natural rate of decline in renal function with age. J Nephrol 2014; Epub ahead of print.
Re: Tissue Engineered Cystoplasty Augmentation for Treatment of Neurogenic Bladder Using Small Intestinal Submucosa: An Exploratory Study F. Zhang and L. Liao J Urol 2014; 192: 544e551.
To the Editor: The authors are to be congratulated for furthering the discussion of the role of urothelial line bladder augmentation as a solution to the problems of inclusion of bowel mucosa in bladder expansion technology. However, previous work not referenced by the authors has strongly suggested that an autoaugmented bladder that is then covered by demusosalized gastric