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William F Owen - One of the best experts on this subject based on the ideXlab platform.
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exploring the reverse j shaped curve between Urea Reduction Ratio and mortality
Kidney International, 1999Co-Authors: William F Owen, Glenn M Chertow, Michael J Lazarus, Nancy L LewAbstract:Exploring the reverse J-shaped curve between Urea Reduction Ratio and mortality. Background Although accepted worldwide as valid measures of dialysis adequacy, neither the Kt/V (Urea clearance determined by kinetic modeling) nor the Urea Reduction Ratio (URR) have unambiguously predicted survival in hemodialysis patients. Because the Ratio Kt/V can be high with either high Kt (clearance × time) or low V (Urea volume of distribution) and V may be a proxy for skeletal muscle mass and nutritional health, we hypothesized that the increase in the relative risk of death observed among individuals dialyzed in the top 10 to 20% of URR or Kt/V values might reflect a competing risk of malnutrition. Methods A total of 3,009 patients who underwent bioelectrical impedance analysis were stratified into quintiles of URR. Laboratory indicators of nutritional status and two bioimpedance-derived parameters, phase angle and estimated total body water, were compared across quintiles. The relationship between dialysis dose and mortality was explored, with a focus on how V influenced the structure of the dose–mortality relationship. Results There were statistically significant differences in all nutritional parameters across quintiles of URR or Kt/V, indicating that patients in the fifth quintile (mean URR, 74.4 ± 3.1%) were more severely malnourished on average than patients in all or some of the other quintiles. The relationship between URR and mortality was decidedly curvilinear, resembling a reverse J shape that was confirmed by statistical analysis. An adjustment for the influence of V on URR or Kt/V was performed by evaluating the Kt-mortality relationship. There was no evidence of an increase in the relative risk of death among patients treated with high Kt. Higher Kt was associated with a better nutritional status. Conclusion We conclude that the increase in mortality observed among those patients whose URR or Kt/V are among the top 10 to 20% of patients reflects a deleterious effect of malnutrition (manifest by a reduced V) that overcomes whatever benefit might be derived from an associated increase in Urea clearance. Identification of patients who achieve extremely high URR (>75%) or single-pooled Kt/V (>1.6) values using standard dialysis prescriptions should prompt a careful assessment of nutritional status. Confounding by protein-calorie malnutrition may limit the utility of URR or Kt/V as a population-based measure of dialysis dose.
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Relationship between Urea Reduction Ratio, demographic characteristics, and body weight for patients in the 1996 National ESRD Core Indicators Project.
American journal of kidney diseases : the official journal of the National Kidney Foundation, 1999Co-Authors: Diane L. Frankenfield, Edmund G Lowrie, William M. Mcclellan, Steven D. Helgerson, Michael V. Rocco, William F OwenAbstract:Abstract The 1996 Health Care Financing AdministRation's (HCFA) Core Indicators Project for in-center, hemodialysis patients collects information on the quality of care delivered in four clinical areas that were anticipated to predict patient outcomes. Included among these clinical performance measurements is the delivered dose of hemodialysis, measured by the fractional Reduction of Urea achieved during a single hemodialysis session (Urea Reduction Ratio [URR]). A random sample (N = 7,310) of adult (aged ≥18 years), in-center hemodialysis patients was selected, and a one-page data collection form for each patient was sent to the dialysis facility in which care was provided during the last quarter of 1995. The dialysis facilities provided information for 6,861 (94%) patients, and at least one paired predialysis and postdialysis blood Urea nitrogen (BUN) concentRation was reported for 6,655 (97%) of these patients. The URR of this cohort was 65.5% ± 8.0% (mean ± SD), and 41% of patients had a URR less than 65%. The mean dialysis session length was 203 minutes, and more than half of the patients received dialysis with a dialyzer membrane with a KUf less than 10 mL/mm Hg/h. The patients with a URR less than 65% had a mean body weight approximately 10 kg greater than patients with a URR of 65% or greater. This relationship was present for all demographic characteristics studied, including age, gender, race, and primary cause of end-stage renal disease (ESRD). Patients receiving dialysis for less than 6 months were more likely to have a URR less than 65% than patients on dialysis for longer periods. By multivariate analysis, variables significantly associated with a delivered URR less than 65% were body weight in the heaviest quartile (odds Ratio [OR] = 6.1), male gender (OR = 2.6), on dialysis therapy less than 6 months (OR = 2.5), youngest quartile of age ( This is a US government work. There are no restrictions on its use.
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Methodological limitations of the ESRD core indicators project: An ESRD network's experience wtih implementing an ESRD quality survey
American journal of kidney diseases : the official journal of the National Kidney Foundation, 1997Co-Authors: William F Owen, Klemens B. Meyer, Gunther Schmidt, Howard AlfredAbstract:Abstract ESRD Network Number 1, composed of Maine, New Hampshire, Vermont, Massachusetts, Connecticut, and Rhode Island, developed a Network Core Indicator Pilot Project using the dialysis units represented on the Medical Review Board. Network 1's Core Indicator Pilot Project aimed to (1) estimate the proportion of end-stage renal disease (ESRD) patients in Network 1 receiving hemodialysis treatments associated with a Urea Reduction Ratio less than 60% to 65%, (2) elucidate the patient characteristics associated with a hemodialysis dose less than 65%, (3) define the processes in the delivery of hemodialysis that limit the provision of an adequate dialysis dose, and (4) initiate the routine collection of measures of dialysis dose, the analysis of those data, and feedback to the participating dialysis units. In the course of the Core Indicator Pilot Project, we observed little uniformity in the sampling method for the postdialysis blood Urea nitrogen sample. Thirty-three percent of the hemodialysis units reported that this critical blood sample was drawn immediately before the dialysis treatment was terminated; 25% were obtained immediately at the end of the dialysis treatment and 42% drew the sample ≥ 5 minutes after all blood was reinfused to the patient. Especially in the presence of unappreciated blood recirculation in the angioaccess or postdialysis Urea rebound, the lack of standardization in obtaining this critical blood sample to support the Urea Reduction Ratio calculation greatly compromises any comparisons of performance across dialysis facilities and may jeopardize patient care. Future ESRD quality improvement efforts must focus not only on the results of the outcome measure but also on the process by which the measure is achieved. These fundamental principles of qualtiy assessment should be considered by policy specialists, payers, providers, and developers of clinical practice guidelines.
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Anemia in hemodialysis patients: variables affecting this outcome predictor.
Journal of the American Society of Nephrology : JASN, 1997Co-Authors: François Madore, Edmund G Lowrie, J M Lazarus, N L Lew, Carlo Brugnara, Kenneth R. Bridges, William F OwenAbstract:Despite the prevalent use of recombinant human erythropoietin (rhEPO), anemia is a frequent finding in hemodialysis patients. The goal of this study was to evaluate the impact of anemia on patient survival and characterize the determinants of hematopoiesis that may be amenable to therapeutic manipulation to enhance rhEPO responsiveness and reduce death risk. Patient characteristics and laboratory data were collected for 21,899 patients receiving hemodialysis three times per week in dialysis centers throughout the United States in 1993. Hemoglobin concentRations (Hb) 110 g/L. Using multiple linear regression, variables of rhEPO administRation (rhEPO dose and percentage of treatments that rhEPO was administered), variables of iron status (serum iron, transferrin satuRation, and ferritin), variables of nutritional status (serum albumin and creatinine concentRation), and the dose of dialysis (Urea Reduction Ratio) were found to be significantly associated with hemoglobin concentRation (P 110 g/L are not associated with further improvements in the odds of death. (3) Laboratory surrogates of iron stores, nutritional status, and the delivered dose of dialysis are predictive of hemoglobin concentRation. Whether manipulation of the factors that improve anemia will also enhance the survival of patients on hemodialysis is unknown and should be evaluated by prospective, interventional studies.
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the Urea Reduction Ratio and serum albumin concentRation as predictors of mortality in patients undergoing hemodialysis
The New England Journal of Medicine, 1993Co-Authors: William F Owen, Edmund G Lowrie, J M LazarusAbstract:Background Among patients with end-stage renal disease who are treated with hemodialysis, solute clearance during dialysis and nutritional adequacy are determinants of mortality. We determined the effects of Reductions in blood Urea nitrogen concentRations during dialysis and changes in serum albumin concentRations, as an indicator of nutritional status, on mortality in a large group of patients treated with hemodialysis. Methods We analyzed retrospectively the demographic characteristics, mortality rate, duRation of hemodialysis, serum albumin concentRation, and Urea Reduction Ratio (defined as the percent Reduction in blood Urea nitrogen concentRation during a single dialysis treatment) in 13,473 patients treated from October 1, 1990, through March 31, 1991. The risk of death was determined as a function of the Urea Reduction Ratio and serum albumin concentRation. Results As compared with patients with Urea Reduction Ratios of 65 to 69 percent, patients with values below 60 percent had a higher risk of ...
Edmund G Lowrie - One of the best experts on this subject based on the ideXlab platform.
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Comparing the Urea Reduction Ratio and the Urea product as outcome-based measures of hemodialysis dose
American journal of kidney diseases : the official journal of the National Kidney Foundation, 2000Co-Authors: Nancy L Lew, J. Michael Lazarus, Edmund G LowrieAbstract:Abstract The Urea Reduction Ratio (URR) and normalized treatment Ratio (Kt/V) are related quantities that have become accepted measures of hemodialysis dose. Recent studies, however, have suggested that they combine two elements, both favorably associated with clinical outcome, as a single Ratio. These elements, Kt and V, may offset each other, producing a complex quantity that does not reflect a true relationship between dialysis exposure and clinical outcome. This project explored and compared the associations of the URR and the {Urea clearance × time} product (Kt) with mortality in a large sample of hemodialysis patients (37,108 patients) during 1998. Survival analyses using conventional techniques were the primary analytic tools. The relationship between URR and survival was U-shaped or J-shaped, with greater relative mortality at both extremes of the URR distribution than at its middle. Thus, identifying a threshold for adequate dialysis was not possible unless one considers also a threshold for overdialysis. Conversely, the association between Kt and outcome was much simpler, reflecting progressive improvement over the range of Kt evaluated here. These analyses suggest that such measures as URR and Kt/V are compound and complex, and that a simpler, more direct, measure, such as the Kt, should be considered to describe hemodialysis dose.
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Relationship between Urea Reduction Ratio, demographic characteristics, and body weight for patients in the 1996 National ESRD Core Indicators Project.
American journal of kidney diseases : the official journal of the National Kidney Foundation, 1999Co-Authors: Diane L. Frankenfield, Edmund G Lowrie, William M. Mcclellan, Steven D. Helgerson, Michael V. Rocco, William F OwenAbstract:Abstract The 1996 Health Care Financing AdministRation's (HCFA) Core Indicators Project for in-center, hemodialysis patients collects information on the quality of care delivered in four clinical areas that were anticipated to predict patient outcomes. Included among these clinical performance measurements is the delivered dose of hemodialysis, measured by the fractional Reduction of Urea achieved during a single hemodialysis session (Urea Reduction Ratio [URR]). A random sample (N = 7,310) of adult (aged ≥18 years), in-center hemodialysis patients was selected, and a one-page data collection form for each patient was sent to the dialysis facility in which care was provided during the last quarter of 1995. The dialysis facilities provided information for 6,861 (94%) patients, and at least one paired predialysis and postdialysis blood Urea nitrogen (BUN) concentRation was reported for 6,655 (97%) of these patients. The URR of this cohort was 65.5% ± 8.0% (mean ± SD), and 41% of patients had a URR less than 65%. The mean dialysis session length was 203 minutes, and more than half of the patients received dialysis with a dialyzer membrane with a KUf less than 10 mL/mm Hg/h. The patients with a URR less than 65% had a mean body weight approximately 10 kg greater than patients with a URR of 65% or greater. This relationship was present for all demographic characteristics studied, including age, gender, race, and primary cause of end-stage renal disease (ESRD). Patients receiving dialysis for less than 6 months were more likely to have a URR less than 65% than patients on dialysis for longer periods. By multivariate analysis, variables significantly associated with a delivered URR less than 65% were body weight in the heaviest quartile (odds Ratio [OR] = 6.1), male gender (OR = 2.6), on dialysis therapy less than 6 months (OR = 2.5), youngest quartile of age ( This is a US government work. There are no restrictions on its use.
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Body weight-for-height relationships predict mortality in maintenance hemodialysis patients
Kidney international, 1999Co-Authors: Joel D. Kopple, Nancy L Lew, Xiaofei Zhu, Edmund G LowrieAbstract:Body weight-for-height relationships predict mortality in maintenance hemodialysis patients. Background Protein-energy malnutrition is a strong predictor of mortality in maintenance hemodialysis (MHD) patients. This association has generally been described for serum chemistry measures of protein-energy malnutrition. We hypothesized that body weight-for-height relationships also predict survival in MHD patients. Methods During the last three months of 1993, data were obtained on 12,965 men and women concerning clinical characteristics (height, postdialysis weight, age, gender, race, and presence or absence of diabetes mellitus) and laboratory measurements (predialysis serum albumin, creatinine and cholesterol, and the Urea Reduction Ratio). Patient survival during the next 12 months was evaluated retrospectively. Results In comparison to values for normal Americans determined from the National Health and Nutrition Evaluation Survey II data, weight-for-height relationships tended to be slightly lower than normal in African American men and women and Caucasian men undergoing MHD and were normal or slightly greater in the taller Caucasian women. In both men and women, the mortality rate decreased progressively as the patients' weight-for-height increased. MHD patients who weighed more than normal had the lowest mortality rates. After adjustment for clinical characteristics and laboratory measurements, the inverse relationship between mortality rates and weight-for-height percentiles was still highly significant for patients within the lower 50th percentile of body weight-for-height. Serum albumin correlated directly with weight-for-height in patients in the lower 50th percentile of weight-for-height. Serum creatinine and cholesterol correlated directly with weight-for-height in the entire population of men and women. In contrast, the Urea Reduction Ratio was inversely correlated with weight-for-height. Conclusions These data indicate that weight-for-height is a strong predictor of 12-month mortality in male and female MHD patients. Multivariate analyses indicate that body weight-for-height is an independent predictor of higher mortality in those patients who are in the lower 50th percentile for this measurement.
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Anemia in hemodialysis patients: variables affecting this outcome predictor.
Journal of the American Society of Nephrology : JASN, 1997Co-Authors: François Madore, Edmund G Lowrie, J M Lazarus, N L Lew, Carlo Brugnara, Kenneth R. Bridges, William F OwenAbstract:Despite the prevalent use of recombinant human erythropoietin (rhEPO), anemia is a frequent finding in hemodialysis patients. The goal of this study was to evaluate the impact of anemia on patient survival and characterize the determinants of hematopoiesis that may be amenable to therapeutic manipulation to enhance rhEPO responsiveness and reduce death risk. Patient characteristics and laboratory data were collected for 21,899 patients receiving hemodialysis three times per week in dialysis centers throughout the United States in 1993. Hemoglobin concentRations (Hb) 110 g/L. Using multiple linear regression, variables of rhEPO administRation (rhEPO dose and percentage of treatments that rhEPO was administered), variables of iron status (serum iron, transferrin satuRation, and ferritin), variables of nutritional status (serum albumin and creatinine concentRation), and the dose of dialysis (Urea Reduction Ratio) were found to be significantly associated with hemoglobin concentRation (P 110 g/L are not associated with further improvements in the odds of death. (3) Laboratory surrogates of iron stores, nutritional status, and the delivered dose of dialysis are predictive of hemoglobin concentRation. Whether manipulation of the factors that improve anemia will also enhance the survival of patients on hemodialysis is unknown and should be evaluated by prospective, interventional studies.
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Survival of Hemodialysis Patients in the United States Is Improved With a Greater Quantity of Dialysis
American journal of kidney diseases : the official journal of the National Kidney Foundation, 1994Co-Authors: Tom F. Parker, Nancy L Lew, Leigh Husni, Wei Huang, Edmund G LowrieAbstract:The mortality rate for hemodialysis patients in the United States is higher than in other industrialized countries. Some attribute this to insufficient quantities of prescribed and delivered dialysis. A multicenter study in Dallas dialysis centers (Dallas Nephrology Associates) was begun in 1989 to assess the impact of increasing the delivered quantity of dialysis on mortality in subsequent years. Dialysis dose was measured by Urea kinetic modeling. Kt/V, reflecting the fractional volume of body water clearance of Urea during a dialysis treatment, was purposefully increased from 1.18 starting in 1989 to 1.46 in 1992. Additionally, the dialysis dose measured by the Urea Reduction Ratio, the fractional Reduction of blood Urea nitrogen concentRation caused by a dialysis treatment, increased from 63.0% to 69.6% between 1990 and 1992. Outcome analytical methods included both crude and standardized mortality rates and mortality Ratios standardized to large end-stage renal disease databases at the United States Renal Data System and at National Medical Care, Inc. Crude mortality rates at Dallas Nephrology Associates decreased from 22.5% in 1989 to 18.1% in 1992. In comparison, between 1990 and 1992 the Urea Reduction Ration in National Medical Care facilities increased from 57.1% to 62.5%. During that time crude mortality rates decreased from 21.8% to 19.5%. Crude mortality in the United States remained essentially unchanged in the same time period. By 1992, Dallas Nephrology Associates and National Medical Care had standardized mortality Ratios of 0.77 and 0.74, respectively, compared with the US dialysis population, indicating almost 30% fewer observed deaths than expected. Monitoring dialysis dose by Urea kinetic modeling or Urea Reduction Ratio are equally effective in predicting improvement in patient survival. Improved survival is possible in the US end-stage renal disease program with greater amounts of dialysis. This strategy can save an estimated 8,000 to 16,000 lives per year.
Andrew Davenport - One of the best experts on this subject based on the ideXlab platform.
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UK Renal Registry 20th Annual Report: Chapter 6 Adequacy of Haemodialysis in UK Adult Patients in 2016: National and Centre-specific Analyses
2018Co-Authors: R Pyart, Retha Steenkamp, W Magadi, Andrew DavenportAbstract:Data regarding the Urea Reduction Ratio (URR) were available for analysis from 63 renal centres and 74% of the prevalent haemodialysis (HD) population in the UK. - Fifty-one centres provided URR data on more than 90% of prevalent HD patients. - The proportion of patients in the UK who met the Renal Association (RA) clinical practice guideline for URR (.65%) has been stable between 88–89% since 2011. - The median URR has been stable over the same period (75%). - There was persistent variation observed between centres, 15 centres attaining the RA clinical practice guideline in .90% of patients and 42 centres attaining the guideline in 70–90% of patients. . Over 95% of the prevalent HD population received dialysis three times a week but 26% did less than four hours per session. - Median URR was similar between patients irrespective of dialysis session duRation.
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UK Renal Registry 18th Annual Report: Chapter 7 Adequacy of Haemodialysis in UK Adult Patients in 2014: National and Centre-specific Analyses.
Nephron, 2016Co-Authors: Andrew Davenport, Catriona Shaw, Retha SteenkampAbstract:Data suitable for Urea Reduction Ratio (URR) analyses were available for 14,761 (71.9%) of the 20,539 patients receiving haemodialysis (HD) in the UK on the 30/9/2014. In 2014, 88.6% of prevalent HD patients achieved a URR .65%. The between centre range of prevalent patients achieving this target was wide (74.9-97.0%). The median URR in 2014 was 75%. URR was greater in those with longer dialysis vintage, with 91.2% of patients who had survived on renal replacement therapy (RRT) for more than two years achieving a URR .65% compared with only 73.4% of those on RRT for less than six months. Large variation between centres in the percentage of patients achieving the UK Renal Association's (RA) URR guideline persists.
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Carbamylated hemoglobin: A potential marker for the adequacy of hemodialysis therapy in end-stage renal failure
Kidney international, 1996Co-Authors: Andrew Davenport, Stephen Jones, Sharad Goel, John P. Astley, Terry FeestAbstract:Urea can dissociate in vivo to form isocyanic acid which can react with hemoglobin to form carbamylated hemoglobin. Previous work has shown that formation of carbamylated hemoglobin depends upon both the severity and the duRation of renal failure. To determine whether carbamylated hemoglobin can be used as an assessment of the adequacy of hemodialysis treatment, we prospectively studied 55 stable patients who regularly attended our hospital dialysis program. Carbamylated hemoglobin was greater in those patients with a Kt/V of 1.1 (120 +/- 8 micrograms VH/gHb versus 99 +/- 7, P < 0.01), and there was a negative correlation with Kt/V (r = -0.37, P = 0.007). There were positive correlations between carbamylated hemoglobin and the time-averaged Urea concentRation (r = 0.4, P = 0.004), and a negative correlation with the Urea Reduction Ratio (r = -0.37, P = 0.01). Carbamylated hemoglobin may therefore be a useful marker of the degree of uremia, just as glycosylated hemoglobin is used in the assessment of patients with diabetes mellitus.
E. Garrigos - One of the best experts on this subject based on the ideXlab platform.
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Urea Reduction Ratio Considering Urea Rebound
Nephron, 1998Co-Authors: Francisco Maduell, J. Garcia-valdecasas, H. Garcia, J. Hdez-jaras, F. Sigüenza, C Del Pozo, R. Giner, R. Moll, E. GarrigosAbstract:An American National Study shows that survival benefits from higher dialysis doses appear to be present up to a Kt/V level of 1.3 or a Urea Reduction Ratio (URR) of 70%. The effect of increasing dialy
Retha Steenkamp - One of the best experts on this subject based on the ideXlab platform.
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UK Renal Registry 20th Annual Report: Chapter 6 Adequacy of Haemodialysis in UK Adult Patients in 2016: National and Centre-specific Analyses
2018Co-Authors: R Pyart, Retha Steenkamp, W Magadi, Andrew DavenportAbstract:Data regarding the Urea Reduction Ratio (URR) were available for analysis from 63 renal centres and 74% of the prevalent haemodialysis (HD) population in the UK. - Fifty-one centres provided URR data on more than 90% of prevalent HD patients. - The proportion of patients in the UK who met the Renal Association (RA) clinical practice guideline for URR (.65%) has been stable between 88–89% since 2011. - The median URR has been stable over the same period (75%). - There was persistent variation observed between centres, 15 centres attaining the RA clinical practice guideline in .90% of patients and 42 centres attaining the guideline in 70–90% of patients. . Over 95% of the prevalent HD population received dialysis three times a week but 26% did less than four hours per session. - Median URR was similar between patients irrespective of dialysis session duRation.
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UK Renal Registry 18th Annual Report: Chapter 7 Adequacy of Haemodialysis in UK Adult Patients in 2014: National and Centre-specific Analyses.
Nephron, 2016Co-Authors: Andrew Davenport, Catriona Shaw, Retha SteenkampAbstract:Data suitable for Urea Reduction Ratio (URR) analyses were available for 14,761 (71.9%) of the 20,539 patients receiving haemodialysis (HD) in the UK on the 30/9/2014. In 2014, 88.6% of prevalent HD patients achieved a URR .65%. The between centre range of prevalent patients achieving this target was wide (74.9-97.0%). The median URR in 2014 was 75%. URR was greater in those with longer dialysis vintage, with 91.2% of patients who had survived on renal replacement therapy (RRT) for more than two years achieving a URR .65% compared with only 73.4% of those on RRT for less than six months. Large variation between centres in the percentage of patients achieving the UK Renal Association's (RA) URR guideline persists.
