In this revision, the hierarchy is simplified and represented by three different models to set analytical performance specifications. There is general agreement that some of these are better suited for certain measurands than for others. Model 1. Based on the effect of analytical performance on clinical outcomesThis can, in principle, be done using different types of studies:1. Direct outcome studies -investigating the impact of analytical performance of the test on clinical outcomes; 2. Indirect outcome studies -investigating the impact of analytical performance of the test on clinical classifications or decisions and thereby on the probability of patient outcomes, e.g., by simulation or decision analysis.Brought to you by | MIT Libraries Authenticated Download Date | 5/11/18 4:25 AM

BACKGROUND: Urinary excretion of albumin indicates kidney damage and is recognized as a risk factor for progression of kidney disease and cardiovascular disease. The role of urinary albumin measurements has focused attention on the clinical need for accurate and clearly reported results. The National Kidney Disease Education Program and the IFCC convened a conference to assess the current state of preanalytical, analytical, and postanalytical issues affecting urine albumin measurements and to identify areas needing improvement. CONTENT:The chemistry of albumin in urine is incompletely understood. Current guidelines recommend the use of the albumin/creatinine ratio (ACR) as a surrogate for the error-prone collection of timed urine samples. Although ACR results are affected by patient preparation and time of day of sample collection, neither is standardized. Considerable intermethod differences have been reported for both albumin and creatinine measurement, but trueness is unknown because there are no reference measurement procedures for albumin and no reference materials for either analyte in urine. The recommended reference intervals for the ACR do not take into account the large intergroup differences in creatinine excretion (e.g., related to differences in age, sex, and ethnicity) nor the continuous increase in risk related to albumin excretion. DISCUSSION:Clinical needs have been identified for standardization of (a) urine collection methods, (b) urine albumin and creatinine measurements based on a complete reference system, (c) reporting of test results, and (d) reference intervals for the ACR.

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Summary Optimal detection and subsequent risk stratification of people with chronic kidney disease (CKD) requires simultaneous consideration of both kidney function (glomerular filtration rate [GFR]) and kidney damage (as indicated by albuminuria or proteinuria). Measurement of urinary albuminuria and proteinuria is hindered by a lack of standardisation regarding requesting, sample collection, reporting and interpretation of tests. A multidisciplinary working group was convened with the goal of developing and promoting recommendations that achieve consensus on these issues. The working group recommended that the preferred method for assessment of albuminuria in both diabetic and non‐diabetic patients is urinary albumin‐to‐creatinine ratio (UACR) measurement in a first‐void spot urine specimen. Where a first‐void specimen is not possible or practical, a random spot urine specimen for UACR is acceptable. The working group recommended that adults with one or more risk factors for CKD should be assessed using UACR and estimated GFR every 1–2 years, depending on their risk‐factor profile. Recommended testing algorithms and sex‐specific cut‐points for microalbuminuria and macroalbuminuria are provided. The working group recommended that all pathology laboratories in Australia should implement the relevant recommendations as a vital component of an integrated national approach to detection of CKD.

Since publication of the Australasian Creatinine Consensus Working Group's position statement in 2005, most Australasian laboratories now automatically report an estimated glomerular filtration rate (eGFR) (based on the Modification of Diet in Renal Disease [MDRD] formula) with results of serum creatinine tests in adults. Anecdotal evidence suggests that automatic reporting of eGFR helps to identify asymptomatic kidney dysfunction at an earlier stage and to develop rational and appropriate management plans. Changes to the measurement and calibration of serum creatinine assays and issues regarding implementation of eGFR in clinical practice led the Australasian Creatinine Consensus Working Group to reconvene in 2007. The recommendations contained here build on the original 2005 position statement and consolidate the role of eGFR in clinical practice. The Working Group recommends that the eGFR upper reporting limit be extended to 90 mL/min/1.73 m2, with eGFR values above this amount being reported as “> 90 mL/min/1.73 m2”, rather than as a precise figure. The Working Group has concluded that it is currently premature to recommend age‐related decision points for eGFR. However, it is appropriate to advise medical practitioners that, in people aged ≥ 70 years, an eGFR in the range 45–59 mL/min/1.73 m2, if stable over time and unaccompanied by other evidence of kidney damage, may be interpreted as consistent with a typical eGFR for this age group and is unlikely to be associated with chronic kidney disease‐related complications. Pending publication of validation studies, the Working Group recommends that Australasian laboratories continue to automatically report eGFR in Aboriginal and Torres Strait Islander peoples and other ethnic groups. The Working Group supports the use of eGFR to assist drug dosing decision making in general practice.