ABSTRACT
BACKGROUND: The accuracy of estimation of kidney function with the use of routine metabolic tests, such as measurement of the serum creatinine level, has been controversial. The European Kidney Function Consortium (EKFC) developed a creatinine-based equation (EKFC eGFRcr) to estimate the glomerular filtration rate (GFR) with a rescaled serum creatinine level (i.e., the serum creatinine level is divided by the median serum creatinine level among healthy persons to control for variation related to differences in age, sex, or race). Whether a cystatin C-based EKFC equation would increase the accuracy of estimated GFR is unknown. METHODS: We used data from patients in Sweden to estimate the rescaling factor for the cystatin C level in adults. We then replaced rescaled serum creatinine in the EKFC eGFRcr equation with rescaled cystatin C, and we validated the resulting EKFC eGFRcys equation in cohorts of White patients and Black patients in Europe, the United States, and Africa, according to measured GFR, levels of serum creatinine and cystatin C, age, and sex. RESULTS: On the basis of data from 227,643 patients in Sweden, the rescaling factor for cystatin C was estimated at 0.83 for men and women younger than 50 years of age and 0.83 + 0.005 × (age - 50) for those 50 years of age or older. The EKFC eGFRcys equation was unbiased, had accuracy that was similar to that of the EKFC eGFRcr equation in both White patients and Black patients (11,231 patients from Europe, 1093 from the United States, and 508 from Africa), and was more accurate than the Chronic Kidney Disease Epidemiology Collaboration eGFRcys equation recommended by Kidney Disease: Improving Global Outcomes. The arithmetic mean of EKFC eGFRcr and EKFC eGFRcys further improved the accuracy of estimated GFR over estimates from either biomarker equation alone. CONCLUSIONS: The EKFC eGFRcys equation had the same mathematical form as the EKFC eGFRcr equation, but it had a scaling factor for cystatin C that did not differ according to race or sex. In cohorts from Europe, the United States, and Africa, this equation improved the accuracy of GFR assessment over that of commonly used equations. (Funded by the Swedish Research Council.).
Subject(s)
Black People , Cystatin C , Glomerular Filtration Rate , Renal Insufficiency, Chronic , White People , Adult , Female , Humans , Infant , Male , Middle Aged , Africa/epidemiology , Biomarkers/blood , Black People/statistics & numerical data , Creatinine/blood , Cystatin C/blood , Europe/epidemiology , Glomerular Filtration Rate/physiology , Race Factors , Renal Insufficiency, Chronic/blood , Renal Insufficiency, Chronic/epidemiology , Renal Insufficiency, Chronic/ethnology , Sex Factors , Sweden/epidemiology , United States/epidemiology , White People/statistics & numerical data , Reproducibility of ResultsABSTRACT
The Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease (CKD) updates the KDIGO 2012 guideline and has been developed with patient partners, clinicians, and researchers around the world, using robust methodology. This update, based on a substantially broader base of evidence than has previously been available, reflects an exciting time in nephrology. New therapies and strategies have been tested in large and diverse populations that help to inform care; however, this guideline is not intended for people receiving dialysis nor those who have a kidney transplant. The document is sensitive to international considerations, CKD across the lifespan, and discusses special considerations in implementation. The scope includes chapters dedicated to the evaluation and risk assessment of people with CKD, management to delay CKD progression and its complications, medication management and drug stewardship in CKD, and optimal models of CKD care. Treatment approaches and actionable guideline recommendations are based on systematic reviews of relevant studies and appraisal of the quality of the evidence and the strength of recommendations which followed the "Grading of Recommendations Assessment, Development, and Evaluation" (GRADE) approach. The limitations of the evidence are discussed. The guideline also provides practice points, which serve to direct clinical care or activities for which a systematic review was not conducted, and it includes useful infographics and describes an important research agenda for the future. It targets a broad audience of people with CKD and their healthcare, while being mindful of implications for policy and payment.
Subject(s)
Kidney Transplantation , Nephrology , Renal Insufficiency, Chronic , Humans , Renal Insufficiency, Chronic/diagnosis , Renal Insufficiency, Chronic/therapy , Renal Insufficiency, Chronic/complications , Kidney Transplantation/adverse effects , Renal Dialysis/adverse effectsABSTRACT
AIM: The Cockcroft-Gault (CG) creatinine-based equation is still used to estimate glomerular filtration rate (eGFR) for drug dosage adjustment. Incorrect eGFR may lead to hazardous over- or underdosing. METHODS: In a cross-sectional analysis, CG was validated against measured GFR (mGFR) in 14 804 participants and compared with the Modification-of-Diet-in-Renal-Diseases (MDRD), Chronic-Kidney-Disease-Epidemiology (CKD-EPI), Lund-Malmö-Revised (LMR) and European-Kidney-Function-Consortium (EKFC) equations. Validation focused on bias, imprecision and accuracy (percentage of estimates within ±30% of mGFR, P30), overall and stratified for mGFR, age and body mass index at mGFR <60 mL/min, as well as classification in mGFR stages. RESULTS: The CG equation performed worse than the other equations, overall and in mGFR, age and BMI subgroups in terms of bias (systematic overestimation), imprecision and accuracy except for patients ≥65 years where bias and P30 were similar to MDRD and CKD-EPI, but worse than LMR and EKFC. In subjects with mGFR <60 mL/min and at BMI 18.5-25 kg/m2 , all equations performed similarly, and for BMI < 18.5 kg/m2 CG and LMR had the best results though all equations had poor P30-accuracy. At BMI ≥ 25 kg/m2 the bias of the CG increased with increasing BMI (+17.2 mL/min at BMI ≥ 40 kg/m2 ). The four more recent equations also classified mGFR stages better than CG. CONCLUSIONS: The CG equation showed poor ability to estimate GFR overall and in analyses stratified for mGFR, age and BMI. CG was inferior to correctly classify the patients in the mGFR staging compared to more recent creatinine-based equations.
Subject(s)
Renal Insufficiency, Chronic , Body Mass Index , Creatinine , Cross-Sectional Studies , Glomerular Filtration Rate , HumansABSTRACT
BACKGROUND: The Chronic Kidney Disease in Children Study (CKiD) equation for children and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation for adults are recommended serum creatinine (SCr)-based calculations for estimating glomerular filtration rate (GFR). However, these equations, as well as their combination, have limitations, notably the problem of implausible changes in GFR during the transition from adolescence to adulthood and overestimation of GFR in young adults. The full age spectrum (FAS) equation addresses these issues but overestimates GFR when SCr levels are low. OBJECTIVE: To develop and validate a modified FAS SCr-based equation combining design features of the FAS and CKD-EPI equations. DESIGN: Cross-sectional analysis with separate pooled data sets for development and validation. SETTING: Research and clinical studies (n = 13) with measured GFR available. PATIENTS: 11 251 participants in 7 studies (development and internal validation data sets) and 8378 participants in 6 studies (external validation data set). MEASUREMENTS: Clearance of an exogenous marker (reference method), SCr level, age, sex, and height were used to develop a new equation to estimate GFR. RESULTS: The new European Kidney Function Consortium (EKFC) equation is a FAS equation with low bias (-1.2 mL/min/1.73 m2 [95% CI, -2.7 to 0.0 mL/min/1.73 m2] in children and -0.9 mL/min/1.73 m2 [CI, -1.2 to -0.5 mL/min/1.73 m2] in adults) across the FAS (2 to 90 years) and SCr range (40 to 490 µmol/L [0.45 to 5.54 mg/dL]) and with fewer estimation errors exceeding 30% (6.5% [CI, 3.8% to 9.1%] in children and 3.1% [CI, 2.5% to 3.6%] in adults) compared with the CKiD and CKD-EPI equations. LIMITATION: No Black patients were included. CONCLUSION: The new EKFC equation shows improved accuracy and precision compared with commonly used equations for estimating GFR from SCr levels. PRIMARY FUNDING SOURCE: Swedish Research Council (Vetenskapsrådet).
Subject(s)
Creatinine/blood , Glomerular Filtration Rate , Adolescent , Adult , Age Factors , Aged , Child , Child, Preschool , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Reproducibility of Results , Sex Factors , Young AdultABSTRACT
BACKGROUND: Urine albumin-to-creatinine ratio (ACR) and protein-to-creatinine ratio (PCR) are used to measure urine protein. Recent guidelines endorse ACR use, and equations have been developed incorporating ACR to predict risk of kidney failure. For situations in which PCR only is available, having a method to estimate ACR from PCR as accurately as possible would be useful. METHODS: We used data from a population-based cohort of 47,714 adults in Alberta, Canada, who had simultaneous assessments of urine ACR and PCR. After log-transforming ACR and PCR, we used cubic splines and quantile regression to estimate the median ACR from a PCR, allowing for modification by specified covariates. On the basis of the cubic splines, we created models using linear splines to develop equations to estimate ACR from PCR. In a subcohort with eGFR<60 ml/min per 1.73 m2, we then used the kidney failure risk equation to compare kidney failure risk using measured ACR as well as estimated ACR that had been derived from PCR. RESULTS: We found a nonlinear association between log(ACR) and log(PCR), with the implied albumin-to-protein ratio increasing from <30% in normal to mild proteinuria to about 70% in severe proteinuria, and with wider prediction intervals at lower levels. Sex was the most important modifier of the relationship between ACR and PCR, with men generally having a higher albumin-to-protein ratio. Estimates of kidney failure risk were similar using measured ACR and ACR estimated from PCR. CONCLUSIONS: We developed equations to estimate the median ACR from a PCR, optionally including specified covariates. These equations may prove useful in certain retrospective clinical or research applications where only PCR is available.
Subject(s)
Albuminuria/diagnosis , Creatinine/urine , Disease Progression , Renal Insufficiency, Chronic/diagnosis , Adult , Aged , Albumins/analysis , Albuminuria/epidemiology , Canada , Cohort Studies , Databases, Factual , Female , Follow-Up Studies , Glomerular Filtration Rate , Humans , Incidence , Male , Middle Aged , Predictive Value of Tests , Regression Analysis , Renal Insufficiency, Chronic/epidemiology , Retrospective Studies , Urinalysis/methodsABSTRACT
When assessing changes in glomerular filtration rate (GFR) it is important to differentiate pathological change from intrinsic biological and analytical variation. GFR is measured using complex reference methods (e.g., iohexol clearance). In clinical practice measurement of creatinine and cystatin C are used in the Modification of Diet in Renal Disease [MDRD] or Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI] equations to provide estimated GFR. Here we studied the biological variability of measured and estimated GFR in twenty nephrology outpatients (10 male, 10 female; median age 71, range 50-80 years) with moderate CKD (GFR 30-59 ml/min per 1.73 m2). Patients underwent weekly GFR measurement by iohexol clearance over four consecutive weeks. Simultaneously, GFR was estimated using the MDRD, CKD-EPIcreatinine, CKD-EPIcystatinC and CKD-EPIcreatinine+cystatinC equations. Within-subject biological variation expressed as a percentage [95% confidence interval] for the MDRD (5.0% [4.3-6.1]), CKD-EPIcreatinine (5.3% [4.5-6.4]), CKD-EPIcystatinC (5.3% [4.5-6.5]), and CKD-EPIcreatinine+cystatinC (5.0% [4.3-6.2]) equations were broadly equivalent. The within-subject biological variation for MDRD and CKD- EPIcreatinine+cystatinC estimated GFR were each significantly lower than that of the measured GFR (6.7% [5.6-8.2]). Reference change values, the point at which a true change in a biomarker in an individual can be inferred to have occurred with 95% probability were calculated. By the MDRD equation, positive and negative reference change values were 15.1% and 13.1% respectively. If an individual's baseline MDRD estimated GFR (ml/min per 1.73 m2) was 59, significant increases or decreases would be to values over 68 or under 51 respectively. Within-subject variability of estimated GFR was lower than measured GFR. Reference change values can be used to understand GFR changes in clinical practice. Thus, estimates of GFR are at least as reliable as measured GFR for monitoring patients over time.
Subject(s)
Glomerular Filtration Rate , Renal Insufficiency, Chronic/physiopathology , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Reference StandardsABSTRACT
BACKGROUND: Although recommended by the Kidney Disease Improving Global Outcomes, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPICR) creatinine equation was not targeted to estimate glomerular filtration rate (eGFR) among older adults. The Berlin Initiative Study (BIS1CR) equation was specifically developed in older adults, and the Lund-Malmö revised (LMRCR) and the Full Age Spectrum (FASCR) equations have shown promising results in older adults. Our aim was to validate these four creatinine equations, including addition of cystatin C in a large multicenter cohort of Europeans ≥70 years. METHODS: A total of 3226 individuals (2638 with cystatin C) underwent GFR measurement (mGFR; median, 44 mL/min/1.73 m2) using plasma iohexol clearance. Bias, precision (interquartile range [IQR]), accuracy (percent of estimates ±30% of mGFR, P30), eGFR accuracy diagrams and probability diagrams to classify mGFR<45 mL/min/1.73 m2 were compared. RESULTS: The overall results of BIS1CR/CKD-EPICR/FASCR/LMRCR were as follows: median bias, 1.7/3.6/0.6/-0.7 mL/min/1.73 m2; IQR, 11.6/12.3/11.1/10.5 mL/min/1.73 m2; and P30, 77.5%/76.4%/80.9%/83.5% (significantly higher for LMR, p<0.001). Substandard P30 (<75%) was noted for all equations at mGFR<30 mL/min/1.73 m2, and at body mass index values <20 and ≥35 kg/m2. LMRCR had the most stable performance across mGFR subgroups. Only LMRCR and FASCR had a relatively constant small bias across eGFR levels. Probability diagrams exhibited wide eGFR intervals for all equations where mGFR<45 could not be confidently ruled in or out. Adding cystatin C improved P30 accuracy to 85.7/86.8/85.7/88.7 for BIS2CR+CYS/CKD-EPICR+CYS/FASCR+CYS/MEANLMR+CAPA. CONCLUSIONS: LMRCR and FASCR seem to be attractive alternatives to CKD-EPICR in estimating GFR by creatinine-based equations in older Europeans. Addition of cystatin C leads to important improvement in estimation performance.
Subject(s)
Creatinine/standards , Cystatin C/standards , Glomerular Filtration Rate , Aged , Aged, 80 and over , Cohort Studies , Creatinine/blood , Cross-Sectional Studies , Cystatin C/blood , Europe , Female , Humans , Male , Middle AgedABSTRACT
Renal dysfunction occurs in 25% to 50% of patients with cirrhosis admitted to the hospital with an acute episode of hepatic decompensation and may be due to underlying chronic kidney disease, an acute deterioration, or both. An acute deterioration in renal function in cirrhotic patients is now collectively referred to as acute kidney injury (AKI), which has been subclassified into different grades of severity that identify prognostic groups. Acute-on-chronic liver failure is characterized by acute hepatic and/or extrahepatic organ failure driven by a dysregulated immune response and systemic inflammatory response. AKI is also one of the defining features of ACLF and a major component in grading the severity of acute-on-chronic liver failure. As such, the pattern of AKI now observed in patients admitted to the hospital with acutely decompensated liver disease is likely to be one of inflammatory kidney injury including acute tubular injury (referred in this review as non-hepatorenal syndrome [HRS]-AKI) rather than HRS. As the management and supportive treatment of non-HRS-AKI potentially differ from those of HRS, then from the nephrology perspective, it is important to distinguish between non-HRS-AKI and HRS-AKI when reviewing patients with acute-on-chronic liver failure and AKI, so that appropriate and early management can be instituted.
Subject(s)
Acute Kidney Injury/diagnosis , Acute-On-Chronic Liver Failure/complications , Hepatorenal Syndrome/diagnosis , Liver Cirrhosis/complications , Acute Kidney Injury/epidemiology , Acute Kidney Injury/etiology , Acute Kidney Injury/therapy , Acute-On-Chronic Liver Failure/therapy , Animals , Biomarkers/analysis , Disease Models, Animal , Hemoperfusion , Hepatorenal Syndrome/epidemiology , Hepatorenal Syndrome/etiology , Hepatorenal Syndrome/therapy , Humans , Incidence , Kidney/pathology , Kidney/physiopathology , Liver/physiopathology , Liver Cirrhosis/therapy , Liver Transplantation , Prognosis , Severity of Illness Index , Vasoconstrictor Agents/therapeutic useABSTRACT
Background: We recently published and validated the new serum creatinine (Scr)-based full-age-spectrum equation (FAS crea ) for estimating the glomerular filtration rate (GFR) for healthy and kidney-diseased subjects of all ages. The equation was based on the concept of normalized Scr and shows equivalent to superior prediction performance to the currently recommended equations for children, adolescents, adults and older adults. Methods: Based on an evaluation of the serum cystatin C (ScysC) distribution, we defined normalization constants for ScysC ( Q cysC = 0.82 mg/L for ages <70 years and Q cysC = 0.95 mg/L for ages ≥70 years). By replacing Scr/ Q crea in the FAS crea equation with ScysC/ Q cysC , or with the average of both normalized biomarkers, we obtained new ScysC-based (FAS cysC ) and combined Scr-/ScysC-based FAS equations (FAS combi ). To validate the new FAS cysC and FAS combi we collected data on measured GFR, Scr, ScysC, age, gender, height and weight from 11 different cohorts including n = 6132 unique white subjects (368 children, aged ≤18 years, 4295 adults and 1469 older adults, aged ≥70 years). Results: In children and adolescents, the new FAS cysC equation showed significantly better performance [percentage of patients within 30% of mGFR (P30) = 86.1%] than the Caucasian Asian Paediatric Adult Cohort equation (P30 = 76.6%; P < 0.0001), or the ScysC-based Schwartz equation (P30 = 68.8%; P < 0.0001) and the FAS combi equation outperformed all equations with P30 = 92.1% (P < 0.0001). In adults, the FAS cysC equation (P30 = 82.6%) performed equally as well as the Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI cysC ) (P30 = 80.4%) and the FAS combi equation (P30 = 89.9%) was also equal to the combined CKD-EPI equation (P30 = 88.2%). In older adults, FAS cysC was superior (P30 = 88.2%) to CKD-EPI cysC (P30 = 84.4%; P < 0.0001) and the FAS combi equation (P30 = 91.2%) showed significantly higher performance than the combined CKD-EPI equation (P30 = 85.6%) (P < 0.0001). Conclusion: The FAS equation is not only applicable to all ages, but also for all recommended renal biomarkers and their combinations.
Subject(s)
Creatinine/blood , Cystatin C/blood , Glomerular Filtration Rate , Renal Insufficiency, Chronic/blood , Adolescent , Adult , Aged , Biomarkers/blood , Child , Child, Preschool , Female , Humans , Infant , Kidney Function Tests , Male , Middle Aged , Renal Insufficiency, Chronic/diagnosis , White People , Young AdultABSTRACT
BACKGROUND: Identification of acute kidney injury (AKI) is predominantly based on changes in plasma creatinine concentration, an insensitive marker. Alternative biomarkers have been proposed. The reference change value (RCV), the point at which biomarker change can be inferred to have occurred with statistical certainty, provides an objective assessment of change in serial tests results in an individual. METHODS: In 80 patients with chronic kidney disease, weekly measurements of blood and urinary biomarker concentrations were undertaken over 6 weeks. Variability was determined and compared before and after adjustment for urinary creatinine and across subgroups stratified by level of kidney function, proteinuria, and presence or absence of diabetes. RESULTS: RCVs were determined for whole blood, plasma, and urinary neutrophil gelatinase-associated lipocalin (111%, 59%, and 693%, respectively), plasma cystatin C (14%), creatinine (17%), and urinary kidney injury molecule 1 (497%), tissue inhibitor of metalloproteinases 2 (454%), N-acetyl-ß-d-glucosaminidase (361%), interleukin-18 (819%), albumin (430%), and α1-microglobulin (216%). Blood biomarkers exhibited lower variability than urinary biomarkers. Generally, adjusting urinary biomarker concentrations for creatinine reduced (P < 0.05) within-subject biological variability (CVI). For some markers, variation differed (P < 0.05) between subgroups. CONCLUSIONS: These data can form a basis for application of these tests in clinical practice and research studies and are applicable across different levels of kidney function and proteinuria and in the presence or absence of diabetes. Most of the studied biomarkers have relatively high CVI (noise) but also have reported large concentration changes in response to renal insult (signal); thus progressive change should be detectable (high signal-to-noise ratio) when baseline data are available.
Subject(s)
Acute Kidney Injury/blood , Acute Kidney Injury/urine , Creatinine/blood , Creatinine/urine , Renal Insufficiency, Chronic/blood , Renal Insufficiency, Chronic/urine , Adult , Aged , Aged, 80 and over , Biomarkers/blood , Biomarkers/urine , Female , Humans , Kidney Function Tests , Male , Middle AgedABSTRACT
Metabolic acidosis is common in advanced chronic kidney disease and has been associated with a range of physiological derangements of importance to the health of older people. These include associations with skeletal muscle weakness, cardiovascular risk factors, and bone and mineral disorders that may lead to fragility fractures. Although metabolic acidosis is associated with accelerated decline in kidney function, end-stage renal failure is a much less common outcome in older, frail patients than cardiovascular death. Correction of metabolic acidosis using bicarbonate therapy is commonly employed, but the existing evidence is insufficient to know whether such therapy is of net benefit to older people. Bicarbonate is bulky and awkward to take, may impose additional sodium load with effects on fluid retention and blood pressure, and may cause gastrointestinal side effects. Trial data to date suggest potential benefits of bicarbonate therapy on progression of renal disease and nutrition, but trials have not as yet been published examining the effect of bicarbonate therapy across a range of domains relevant to the health of older people. Fortunately, a number of trials are now underway that should allow us to ascertain whether bicarbonate therapy can improve physical function, quality of life, and vascular, bone and kidney health in older people, and hence decide whether any benefits seen outweigh adverse effects and additional treatment burden in this vulnerable group of patients.
Subject(s)
Acidosis/epidemiology , Acidosis/etiology , Renal Insufficiency, Chronic/complications , Disease Progression , Humans , Renal Insufficiency, Chronic/physiopathologyABSTRACT
BACKGROUND: Glomerular filtration rate (GFR) is accepted as the best indicator of kidney function and is commonly estimated from serum creatinine (SCr)-based equations. Separate equations have been developed for children (Schwartz equation), younger and middle-age adults [Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation] and older adults [Berlin Initiative Study 1 (BIS1) equation], and these equations lack continuity with ageing. We developed and validated an equation for estimating the glomerular filtration rate that can be used across the full age spectrum (FAS). METHODS: The new FAS equation is based on normalized serum creatinine (SCr/Q), where Q is the median SCr from healthy populations to account for age and sex. Coefficients for the equation are mathematically obtained by requiring continuity during the paediatric-adult and adult-elderly transition. Research studies containing a total of 6870 healthy and kidney-diseased white individuals, including 735 children, <18 years of age, 4371 adults, between 18 and 70 years of age, and 1764 older adults, ≥70 years of age with measured GFR (inulin, iohexol and iothalamate clearance) and isotope dilution mass spectrometry-equivalent SCr, were used for the validation. Bias, precision and accuracy (P30) were evaluated. RESULTS: The FAS equation was less biased [-1.7 (95% CI -3.4, -0.2) versus 6.0 (4.5, 7.5)] and more accurate [87.5% (85.1, 89.9) versus 83.8% (81.1, 86.5)] than the Schwartz equation for children and adolescents; less biased [5.0 (4.5, 5.5) versus 6.3 (5.9, 6.8)] and as accurate [81.6% (80.4, 82.7) versus 81.9% (80.7, 83.0)] as the CKD-EPI equation for young and middle-age adults; and less biased [-1.1 (-1.6, -0.6) versus 5.6 (5.1, 6.2)] and more accurate [86.1% (84.4, 87.7) versus 81.8% (79.7, 84.0)] than CKD-EPI for older adults. CONCLUSIONS: The FAS equation has improved validity and continuity across the full age-spectrum and overcomes the problem of implausible eGFR changes in patients which would otherwise occur when switching between more age-specific equations.
Subject(s)
Biomarkers/analysis , Glomerular Filtration Rate , Kidney/physiopathology , Models, Theoretical , Renal Insufficiency, Chronic/diagnosis , Adolescent , Adult , Age Factors , Aged , Child , Child, Preschool , Cohort Studies , Female , Humans , Infant , Kidney Function Tests , Male , Middle Aged , Renal Insufficiency, Chronic/metabolism , Young AdultABSTRACT
Clinical practice guidelines provide guidance in decision making relating to diagnosis, management, and treatment in specific areas of health care. They play an essential role in the evaluation and synthesis of an ever-expanding evidence base and are of increasing importance in aging societies with a high prevalence of overlapping disease comorbid conditions. Integration of chronic disease guidance is essential, particularly in older people, in order to understand critical disease interactions and the potential adverse effects that individual guideline statements may engender in different disease areas. This requires a need for flexibility that not only recognizes the differences in patients' characteristics, but also their preferences for medical interventions and health outcomes. The question is how this can be achieved. In this article, we look at the standardization of clinical practice guidelines from the chronic kidney disease standpoint and consider how tools for integrating guidelines, such as the ADAPTE process and the knowledge-to-action cycle, can be used to guide appropriate decision making and take account of patient choice in older adults with multimorbidity.
Subject(s)
Choice Behavior , Patient Preference , Practice Guidelines as Topic/standards , Renal Insufficiency, Chronic/diagnosis , Renal Insufficiency, Chronic/therapy , Age Factors , Aged , Comorbidity , Humans , Renal Insufficiency, Chronic/epidemiologyABSTRACT
BACKGROUND: Experts recommend screening for albuminuria in patients at risk for kidney disease. PURPOSE: To systematically review evidence about the diagnostic accuracy of point-of-care (POC) tests for detecting albuminuria in individuals for whom guidelines recommend such detection. DATA SOURCES: Cochrane Library, EMBASE, Medion database, MEDLINE, and Science Citation Index from 1963 through 5 December 2013; hand searches of other relevant journals; and reference lists. STUDY SELECTION: Cross-sectional studies, published in any language, that compared the accuracy of machine-read POC tests of urinary albumin-creatinine ratio with that of laboratory measurement. DATA EXTRACTION: Two independent reviewers extracted study data and assessed study quality using the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies 2) tool. DATA SYNTHESIS: Sixteen studies (n = 3356 patients) that evaluated semiquantitative or quantitative POC tests and used random urine samples collected in primary or secondary ambulatory care settings met inclusion criteria. Pooling results from a bivariate random-effects model gave sensitivity and specificity estimates of 76% (95% CI, 63% to 86%) and 93% (CI, 84% to 97%), respectively, for the semiquantitative test. Sensitivity and specificity estimates for the quantitative test were 96% (CI, 78% to 99%) and 98% (CI, 93% to 99%), respectively. The negative likelihood ratios for the semiquantitative and quantitative tests were 0.26 (CI, 0.16 to 0.40) and 0.04 (CI, 0.01 to 0.25), respectively. LIMITATION: Accuracy estimates were based on data from single-sample urine measurement, but guidelines require that diagnosis of albuminuria be based on at least 2 of 3 samples collected in a 6-month period. CONCLUSION: A negative semiquantitative POC test result does not rule out albuminuria, whereas quantitative POC testing meets required performance standards and can be used to rule out albuminuria. PRIMARY FUNDING SOURCE: None.
Subject(s)
Albuminuria/diagnosis , Point-of-Care Systems/standards , Humans , Likelihood Functions , Quality Assurance, Health Care , Sensitivity and SpecificityABSTRACT
PURPOSE OF REVIEW: Glomerular filtration rate (GFR) is the best overall measure of kidney function. Reference GFR measurements (e.g. inulin clearance) are laborious. Estimation of GFR using equations based on endogenous filtration markers is simpler, cheaper and easy to apply in practice but suffers from limited accuracy and reproducibility. This review summarizes the recent studies comparing measured and estimated GFR in various populations and disease settings. We consider the utility of newer estimating equations based on standardized methodology, including those incorporating cystatin C. RECENT FINDINGS: Equations proposed by the Chronic Kidney Disease-Epidemiology (CKD-EPI) Consortium slightly improve the accuracy of GFR estimation compared with those used formerly. The black ethnicity coefficient in the CKD-EPI equation may not be transferable across other black populations and the equations require further validation in other ethnic groups. All currently reported equations fall short of ideal. Incorporation of cystatin C into the CKD-EPI equation improves precision and offers hope of a GFR estimate that may not require ethnic adjustment. SUMMARY: The ideal biomarker and equation to estimate GFR would provide reproducible and accurate results across the entire range of GFRs, populations and diseases. Newer GFR markers and equations are required to fulfil this holy grail of research.
Subject(s)
Glomerular Filtration Rate , Kidney/physiopathology , Models, Biological , Renal Insufficiency, Chronic/diagnosis , Biomarkers/metabolism , Creatinine/metabolism , Cystatin C/metabolism , Humans , Kidney/metabolism , Predictive Value of Tests , Prognosis , Racial Groups , Renal Insufficiency, Chronic/ethnology , Renal Insufficiency, Chronic/metabolism , Renal Insufficiency, Chronic/physiopathology , Risk FactorsABSTRACT
BACKGROUND: Uncertainty exists regarding the optimal method to estimate glomerular filtration rate (GFR) for disease detection and monitoring. Widely used GFR estimates have not been validated in British ethnic minority populations. METHODS/DESIGN: Iohexol measured GFR will be the reference against which each estimating equation will be compared. The estimating equations will be based upon serum creatinine and/or cystatin C. The eGFR-C study has 5 components: 1) A prospective longitudinal cohort study of 1300 adults with stage 3 chronic kidney disease followed for 3 years with reference (measured) GFR and test (estimated GFR [eGFR] and urinary albumin-to-creatinine ratio) measurements at baseline and 3 years. Test measurements will also be undertaken every 6 months. The study population will include a representative sample of South-Asians and African-Caribbeans. People with diabetes and proteinuria (ACR ≥30 mg/mmol) will comprise 20-30% of the study cohort.2) A sub-study of patterns of disease progression of 375 people (125 each of Caucasian, Asian and African-Caribbean origin; in each case containing subjects at high and low risk of renal progression). Additional reference GFR measurements will be undertaken after 1 and 2 years to enable a model of disease progression and error to be built.3) A biological variability study to establish reference change values for reference and test measures.4) A modelling study of the performance of monitoring strategies on detecting progression, utilising estimates of accuracy, patterns of disease progression and estimates of measurement error from studies 1), 2) and 3).5) A comprehensive cost database for each diagnostic approach will be developed to enable cost-effectiveness modelling of the optimal strategy.The performance of the estimating equations will be evaluated by assessing bias, precision and accuracy. Data will be modelled as a linear function of time utilising all available (maximum 7) time points compared with the difference between baseline and final reference values. The percentage of participants demonstrating large error with the respective estimating equations will be compared. Predictive value of GFR estimates and albumin-to-creatinine ratio will be compared amongst subjects that do or do not show progressive kidney function decline. DISCUSSION: The eGFR-C study will provide evidence to inform the optimal GFR estimate to be used in clinical practice. TRIAL REGISTRATION: ISRCTN42955626.
Subject(s)
Albuminuria/diagnosis , Albuminuria/ethnology , Creatinine/blood , Cystatin C/blood , Glomerular Filtration Rate , Renal Insufficiency, Chronic/diagnosis , Renal Insufficiency, Chronic/ethnology , Adolescent , Adult , Age Distribution , Aged , Albuminuria/blood , Causality , Comorbidity , Disease Progression , Female , Humans , Longitudinal Studies , Male , Middle Aged , Prospective Studies , Renal Insufficiency, Chronic/blood , Reproducibility of Results , Research Design , Sensitivity and Specificity , Sex Distribution , United Kingdom/epidemiology , Young AdultABSTRACT
Background: Estimation of glomerular filtration rate using equations based on creatinine is widely used to manage chronic kidney disease. In the UK, the Chronic Kidney Disease Epidemiology Collaboration creatinine equation is recommended. Other published equations using cystatin C, an alternative marker of kidney function, have not gained widespread clinical acceptance. Given higher cost of cystatin C, its clinical utility should be validated before widespread introduction into the NHS. Objectives: Primary objectives were to: (1) compare accuracy of glomerular filtration rate equations at baseline and longitudinally in people with stage 3 chronic kidney disease, and test whether accuracy is affected by ethnicity, diabetes, albuminuria and other characteristics; (2) establish the reference change value for significant glomerular filtration rate changes; (3) model disease progression; and (4) explore comparative cost-effectiveness of kidney disease monitoring strategies. Design: A longitudinal, prospective study was designed to: (1) assess accuracy of glomerular filtration rate equations at baseline (nâ =â 1167) and their ability to detect change over 3 years (nâ =â 875); (2) model disease progression predictors in 278 individuals who received additional measurements; (3) quantify glomerular filtration rate variability components (nâ =â 20); and (4) develop a measurement model analysis to compare different monitoring strategy costs (nâ =â 875). Setting: Primary, secondary and tertiary care. Participants: Adults (≥ 18 years) with stage 3 chronic kidney disease. Interventions: Estimated glomerular filtration rate using the Chronic Kidney Disease Epidemiology Collaboration and Modification of Diet in Renal Disease equations. Main outcome measures: Measured glomerular filtration rate was the reference against which estimating equations were compared with accuracy being expressed as P30 (percentage of values within 30% of reference) and progression (variously defined) studied as sensitivity/specificity. A regression model of disease progression was developed and differences for risk factors estimated. Biological variation components were measured and the reference change value calculated. Comparative costs of monitoring with different estimating equations modelled over 10 years were calculated. Results: Accuracy (P30) of all equations was ≥ 89.5%: the combined creatinine-cystatin equation (94.9%) was superior (pâ <â 0.001) to other equations. Within each equation, no differences in P30 were seen across categories of age, gender, diabetes, albuminuria, body mass index, kidney function level and ethnicity. All equations showed poor (< 63%) sensitivity for detecting patients showing kidney function decline crossing clinically significant thresholds (e.g. a 25% decline in function). Consequently, the additional cost of monitoring kidney function annually using a cystatin C-based equation could not be justified (incremental cost per patient over 10 yearsâ =â £43.32). Modelling data showed association between higher albuminuria and faster decline in measured and creatinine-estimated glomerular filtration rate. Reference change values for measured glomerular filtration rate (%, positive/negative) were 21.5/-17.7, with lower reference change values for estimated glomerular filtration rate. Limitations: Recruitment of people from South Asian and African-Caribbean backgrounds was below the study target. Future work: Prospective studies of the value of cystatin C as a risk marker in chronic kidney disease should be undertaken. Conclusions: Inclusion of cystatin C in glomerular filtration rate-estimating equations marginally improved accuracy but not detection of disease progression. Our data do not support cystatin C use for monitoring of glomerular filtration rate in stage 3 chronic kidney disease. Trial registration: This trial is registered as ISRCTN42955626. Funding: This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 11/103/01) and is published in full in Health Technology Assessment; Vol. 28, No. 35. See the NIHR Funding and Awards website for further award information.
Chronic kidney disease, which affects approximately 14% of the adult population, often has no symptoms but, in some people, may later develop into kidney failure. Kidney disease is most often detected using a blood test called creatinine. Creatinine does not identify everyone with kidney disease, or those most likely to develop more serious kidney disease. An alternative blood test called cystatin C may be more accurate, but it is more expensive than the creatinine test. We compared the accuracy of these two tests in more than 1000 people with moderate kidney disease. Participants were tested over 3 years to see if the tests differed in their ability to detect worsening kidney function. We also wanted to identify risk factors associated with loss of kidney function, and how much the tests normally vary to better understand what results mean. We compared the accuracy and costs of monitoring people with the two markers. Cystatin C was found slightly more accurate than the creatinine test at estimating kidney function when comparing the baseline single measurements (95% accurate compared to 90%), but not at detecting worsening function over time. This means that the additional cost of monitoring people over time with cystatin C to detect kidney disease progression could not be justified. Kidney test results could vary by up to 20% between tests without necessarily implying changes in underlying kidney function this is the normal level of individual variation. Cystatin C marginally improved accuracy of kidney function testing but not ability to detect worsening kidney function. Cystatin C improves identification of moderate chronic kidney disease, but our results do not support its use for routine monitoring of kidney function in such patients.