J Clin Pathol 1984;37:415-423

Evolution of a national urine quality assurance

programme: the Australasian experience, 1981-1983MDS SHEPHARD, LA PENBERTHY, CG FRASER*

From the Department of Clinical Biochemistry, Flinders Medical Centre, Bedford Park,South Australia 5042, Australia

SUMMARY A national interlaboratory quality assurance programme for quantitative urineanalysis has been conducted over the past three years in Australasia under the auspices of theRoyal College of Pathologists of Australasia and the Australian Association of Clinical Biochem-ists.

Analysis of urine calcium has consistently improved over the three year period whereas urineprotein analysis has consistently declined. Based on the findings in 1983, it is considered thaturine sodium, potassium, creatinine, phosphate, glucose, and chloride are currently being meas-

ured satisfactorily by Australasian laboratories, while the analyses of urine proteins, urate, oxa-

late, 5-hydroxyindoleacetic acid and 4-hydroxy-3-methoxymandelic acid still require substantialimprovement.

All analyses performed in the clinical biochemistrylaboratory should be assessed through interlabora-tory quality assurance survey. A plethora of suchsurveys of regional, national, and internationalnatures exist for those analytes in serum or plasmawhich are the major source of work for the clinicalbiochemist. In contrast, there are few reports on thedesign and execution of quality assurance surveysconcerned with the performance of analysis of otherbody fluids. Although quantitative analysis of urinerepresents a minor but nevertheless important com-ponent of the workload of most laboratories, thereare, with the exception of the urine surveys of theCollege of American Pathologists,'-3 few reports onquality assurance programmes for analytes in thisbiological fluid. In 1980 a small scale regional surveyof the performance of quantitative analysis of uri-nary analytes was therefore carried out in SouthAustralia as a necessary prerequisite to the futureestablishment of an Australasian urine qualityassurance survey.4Under the auspices of the Australian Association

of Clinical Biochemists and the Royal College ofPathologists of Australasia, a programme was insti-tuted in 1981 to assess the standard of performance

*Present address: Department of Biochemical Medicine,- Ninewels-Hospital and Medical School, University of Dundee, Dundee DD19SY, Scotland.

Acceptedfor publication -15 December 1983

of the quantitative analysis of 10 urinary con-stituents throughout Australasia.5 The constituentssurveyed were sodium, potassium, osmolality, urea,creatinine, calcium, phosphate, urate, proteins, andglucose. The programme was also designed to pro-vide rapid feedback to participants on their com-parative performance and included novel featuressuch as the use of target values, allowable limits fortotal laboratory error, linearly related analyte con-centrations for all samples distributed, and compu-ter generation of graphic interim and final reports.

In 1982, the Australasian Urine Programme wassimilarly conducted,6 with the range of analytes sur-veyed being extended to include chloride, oxalate,4-hydroxy-3-methoxymandelic acid (HMMA), and5-hydroxyindoleacetic acid (5HIAA).

In 1983 a further survey was conducted in orderto provide continuing review of the standard of per-formance of urine analyses.' The range of analyteswas further extended to include amylase (EC3.2.2.1).Through the evolution of the Australasian Urine

Programme over the past three years, a number ofanalytical problems have been highlighted and thestandard of performance achieved by laboratoriesfor certain urine chemistries has improved substan-tially. This paper summarises the programmesimplemented and the results obtained over the threeyears and reviews the progress made towardsattempting to raise the standard of performance of

415

416Table 1 Participants in the Australasian urineprogrammes: 1981-1983

State or country No of laboratories

1981 1982 1983

New South Wales 32 35 33Northern Territory 1 2 2Queensland 14 11 13South Australia 5 4 6Tasmania 3 5 4Victoria 19 24 24Western Australia 4 5 7New Zealand 8 9 11

Total 86 95 100

quantitative urine analysis in Australasia. Summaryreports of each year's results have been made avail-able to participants and published in national pro-fessional journals.5'

Material and methods

PARTICIPANTSA total of 86, 95, and 100 laboratories participatedin the 1981, 1982, and 1983 surveys respectively. Abreakdown of participants by state and country isshown in Table 1. Of the 100 laboratories that par-

ticipated in the 1983 programme, 58 participated inthe 1981 programme, 69 in the 1982 programme,and 47 in all three programmes.

SURVEY SAMPLESBefore the start of each survey participants were

required to complete a questionnaire concerning themethods, instruments, standards, and quality controlmaterials used in analysis and on the units and refer-ence ranges used in reporting results.

During each year, at roughly two to three monthlyintervals, 12 samples (in three batches of four), sixsamples (in three batches of two), and six samples(in three batches of two) were sent in 1981, 1982,and 1983 respectively to all participants togetherwith a detailed instruction sheet and colour codedresult sheets.

In 1981, all survey samples were generated in thelaboratory of the survey organisers from a single lotof Ortho Control Urine I (Ortho Diagnostics, Rari-tan, NJ 08869). An appropriate number of vialswere reconstituted with a defined volume of recon-

stitution material to generate a series of sampleswith linearly related concentrations. After recon-

stitution, 10 ml aliquots were dispensed into labelledplastic tubes, and these liquid samples were thendistributed to participants by air cargo.

In 1982 vials of lyophilised urine quality controlmaterial, to be reconstituted by the participatinglaboratory, were distributed by the survey organ-

Shephard, Penberthy, Fraser

isers, together with appropriate reconstitutioninstructions. By varying the volume of distilledwater used for reconstitution, a further set oflinearly related samples was- generated from a sec-ond single batch of Ortho Control Urine.

In 1983 survey material was prepared, to thespecifications of the survey organisers, by the Com-monwealth Serum Laboratories (Parkville, Victoria3052); such material was totally human in origin.Vials of lyophilised material, each containing 25 ml,together with appropriate reconstitution instructionswere sent in kit form directly by the CommonwealthSerum Laboratories to all participants. The sampleswere again linearly related.

RETURN OF RESULTSIn each survey result sheets were required to bereturned to the survey organisers by a previously setcut off date; data received were entered into a com-puter data base, which held the laboratory codenumber and method data of each participant. Overthe three years, on average, an 80% return of resultswas achieved by participating laboratories.

GENERATION OF INTERIM REPORTSAbout two weeks after the nominated date forreturn of results, individual reports, as described indetail previously,58 were sent to each laboratory.

TARGET VALUESIn 1981 and 1982 target values were, in general,assigned to the base material by replicate analysisperformed at three selected reference laboratoriesin South Australia using a number of differentmethods and instrumental techniques. Since, asshown in Table 2, the target values obtained werealmost identical to the consensus mean obtainedfrom all results excluding outliers (defined as resultsgreater than +3 SD from the overall mean), wedecided to use the truncated consensus mean as thetarget value in 1983.

ALLOWABLE LIMITS OF ERRORAllowable limits for total laboratory error9 were setas described previously57 and are listed, for ease ofreference, in Table 3.

SUMMARY REPORTAt the end of each survey a written report, togetherwith a statistical summary, was sent to all partici-pants. By using linearly related samples it was poss-ible to analyse the results of a particular laboratoryusing linear regression analysis. The results fromeach participant were compared with the targetvalue for each analyte and the line of best fit thendetermined. The lowest and highest samples distri-

Evolution of a national urine quality assurance programme: the Australasian experience, 1981-1983 417

Table 2 Comparison of target and consensus values for lowest and highest samples distributed in 1981 and 1982

Analyte Low sample High sample

1981 1982 1981 1982

Target Consensus Target Consensus Target Consensus Target Consensus

Sodium (mmol/1) 74 76 128 129 249 248 252 251Potassium (mmol/1) 31 32 28 28 105 103 54 52Osmolality (mmol/kg) 441 441 494 491 1482 1463 971 965Urea (mmoi/l) 206 213 170 171 692 702 333 329Creatinine (mmol/1) 7-4 7-3 6-3 6-4 24-9 23-6 12-4 12-0Calcium (mmoIl) 2-65 2-62 1-08 1-10 8-80 8-74 2-11 2-09Phosphate (mmol/1) 12-0 12-3 13-1 13-9 40-6 40-0 25 7 25 8Urate (mmoL/l) 0*58 0-52 0-59 0 56 1-96 1-74 1-16 1.01Proteins (g/l) 0-36 0-36 0-27 0-31 2-20 2-17 0 53 0 55Glucose (mmol/l) 0-5 0-7 10-6 9-7 22-8 23-2 20-8 19-3

Table 3 Limits for total laboratory error

Analyte Allowable limit of error

Sodium (mmol/l) + 10Potassium (mmoIl) ±5Osmolality (mmol/kg) ±5 at <300

±10 at 300-500±20 at >500

Urea (mmol/1) ±20Creatinine (mmol/l) ±2Calcium (mmol/1) ±0-2Phosphate (mmol/1) ±2 5Urate (mmol/1) ±0 25Proteins (g/l) +0.1

Overall imprecision (SD) was calculated as thestandard error of the estimate about the line of bestfit and was considered to reflect the average labora-tory SD over the range of results submitted. Impre-cision and bias were also ranked from the lowest tothe highest value. The median value was selected asthe "average laboratory performance" for theparameter concerned.

Results and discussion

Glucose (mmol/1) -I at a1u CALIBRATION MATERIALS

Chloride (mmol/1) ±10 The range of calibration materials used by partici-Oxalate (mmoll) ±0 05 pants over the three year period is shown in Table 4.HMMA (gmoUl/l ±20 at >100 Other materials used as calibrants that are not5H1AA (gmol/1) ±20 at G100 detailed in Table 4 include commercial cerebrospi-Amylase (UIl) ±20% at >100 nal fluid and serum quality control material and

National Bureau of Standards (Washington, DC20234) material for the calibration of urea and cal-cium analyses. We believe that calibration materialsshould have a matrix similar to, if not identical with,

buted were used as the extremes of the linear regres- the fluid being analysed, and therefore consider thatsion. Bias was calculated from the formula: the use of serum based material for the calibration

Average bias = low sample bias + midpoint bias + high sample of urine analyses is not satisfactory. The use of qual-bias ity control materials as calibrants is totally inappro-3 priate. The encouraging trend away from serum

Table 4 Calibration materials used in the Australasian urine programmes: 1981-1983 (percentages)

Analyte

SodiumPotassiumOsmolalityUreaCreatinineCalciumPhosphateUrateProteinsGlucoseChlorideOxalateHMMA5HIAAAmylase

83 78 87 7 8 8 64 83 83 14 6 8 1 3 183 78 87 7 8 8 77 83 83 14 6 8 1 3 151 49 55 6 4 0 88 76 85 6 18 15 - - -62 67 66 42 34 48 32 45 36 24 16 14 1 3 284 77 87 33 29 37 36 45 47 30 21 16 1 4 176 73 79 36 32 39 32 37 39 32 26 30 1 4 173 63 75 53 44 64 27 38 16 19 16 20 - 2 -74 69 80 50 46 63 32 38 24 18 14 13 - 1 173 69 80 60 32 64 10 22 10 27 23 24 3 6 331 34 33 22 26 21 39 44 42 39 26 36 - - -- 48 45 - 17 11 - 67 69 - 17 20 - - -- 14 18 - - - - - - - 100 100 - - -- 26 42 - 4 2 - - 3 - 81 90- - 5- 29 37 - - - - 7 - - 93 100 - - -- - 27 - - 100 - - - - - -

No of responses Commercial serun Commercial aqueous In-house aqueous Urine quality control

1 981 1 982 1 983 1 981 1 982 1 983 1 981 1 982 1 983 1 981 1 982 1 983 1 981 1 982 1 983

Table 5 Quality control material used in the Australasian urine programmes: 1981-1983 (percentages)

Analyte No of responses Commercial urine In-house urine Commercial serum Commercial aqueous None used

1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983

Sodium 72 73 86 48 63 60 6 3 1 34 25 31 5 3 1 7 4 6Potassium 72 73 86 48 63 60 6 3 1 34 25 31 5 3 1 7 4 6Osmolality 53 48 57 32 35 46 - 2 - 38 31 37 21 27 16 9 2 2Urea 69 61 65 43 44 48 1 2 3 46 44 46 1 2 - 6 5 2Creatinine 84 72 85 46 56 53 6 1 2 43 37 40 - - - 5 3 5Calcium 81 68 81 35 56 48 2 - 1 57 41 47 4 1 - 2 1 4Phosphate 74 62 75 32 47 44 1 -. 1 59 48 52 3 2 - 4 3 3Urate 72 67 78 38 46 44 - - - 56 48 51 3 1 - 4 4 5Proteins 76 66 77 48 59 57 - - 5 39 24 31 - - - 8 9 6Glucose 34 29 36 42 48 33 1 - - 53 48 61 1 - - 3 3 6Chloride - 42 42 - 55 45 - - - - 38 52 - 2 - - 5 2Oxalate - 17 16 - 24 25 - 41 50 - - - - - - - 35 25HMMA - 25 42 - 88 86 - 4 10.- - - 8 5SHIAA - 28 36 - 79 78 - 11 11 - -.-- 11 11Amylase - - 70 - - 6 - 89 6

Table 6 Range ofanalyte concentrations for urine survey samples 1981-1983 (consensus means for lowest and highestconcentrations ofanalyte)

Analyte 1981 1982 1983

Low High Midpoint Low High Midpoint Low High Midpoint

Sodium (mmol1) 76 248 162 129 251 190 20 115 68Potassium (mmol1) 32 103 68 28 52 40 19 91 55Osmolality (mmol/kg) 441 1463 952 491 965 728 106 896 501Urea (mmoL/l) 213 702 458 171 329 250 21 471 246Creatinine (mmol/1) 7-3 23-6 15-5 6-4 12-0 9-2 2-1 18-9 10-5Calcium (mmol/1) 2-62 8-74 5-7 1-10 2-07 1-6 1-17 3-72 2 45Phosphate (mmol/l) 12-3 400 26 13-7 25-8 20 4-9 17-7 11-2Urate (mmoi/l) 0 52 1-74 1-1 0-56 1.01 0-8 1-59 2-49 2-04Proteins (g/l) 0-36 2-17 1-27 0-31 0-55 0 43 0.10 1-88 0 99Glucose (mmol/1) 0 7 23-2 12 9 7 19-3 14-5 0-5 17-9 9-2Chloride (mmol/l) - - - 117 227 172 24 130 77Oxalate (mmol/l) - - - 0-16 0-25 0-21 0.11 0-46 0-29HMMA (,molll) - - - 60 96 78 11 140 76SHIAA (Amol/l) - - - 63 108 86 36 177 107Amylase (U/I) - - - - - - 60 680 370

based calibrants seen in 1982 did not continue in lated: the number of laboratories participating; the1983 and, for most analytes, the use of such material classification of methods used and the number ofbecame even higher than in 1981. laboratories using those methods; the total number

of results submitted; the number and percentage ofQUALITY CONTROL MATERIALS blunders (defined as those results outside the targetThe range of quality control materials used is shown value + three times the allowable limits of error);in Table 5. In addition, equine serum and spinal the number and percentage of unacceptable resultsfluid quality control materials have been used as (defined as those results outside the allowable limitssuch for the analysis of proteins; we believe that of error); and the imprecision and bias, ranked atsuch materials should not be used. As with calibra- various intervals or percentiles.tion materials, the positive trend in 1982 towards Using the wealth of data available to the surveylaboratories using urine materials for quality control organisers, an attempt has been made to draw objec-in preference to serum materials was reversed in tive conclusions on the overall standard of perfor-1983. It is incomprehensible that a large proportion mance of each analysis over the three year period.of participants consistently continues not to use any Owing to the fact that (a) the survey material usedform of quality control to monitor analytical per- was of differing origins, (b) the range of analyte con-formance; this is particularly of concern for the centrations for the survey samples was very differentanalysis of urinary oxalate, where the standard of from one year to the next, as shown in Table 6, andperformance is poor. (c) the laboratories participating in each survey were

not the same, this task has proved rather difficult.OVERALL STANDARD OF PERFORMANCE Throughout the evolution of the urine programme,At the end of each survey the following were calcu- however, identical allowable limits for total laborat-

418 Shephard, Penberthy, Fraser

Evolution of a national urine quality assurance programme: the Australasian experience, 1981-1983 419

Table 7 Percentage ofunacceptable results in theAustralasian urine programmes for all participants and forthe 47 laboratories that participated in all three surveys

Analyte Percentage of unacceptable results

All laboratories 47 laboratories

1981 1982 1983 1981 1982 1983

Sodium 8 17 6 7 16 4Potassium 7 10 12 6 10 9Osmolality 30 30 25 28 24 26Urea 45 27 28 45 20 26Creatinine 17 4 11 14 5 8Calcium 51 25 22 52 23 22Phosphate 25 26 15 19 25 12Urate 38 37 82 39 38 83Proteins 37 39 54 33 30 51Glucose 13 21 4 18 17 2Chloride - 14 5 - 16 4Oxalate - 62 48 - 66 58HMMA - 39 41 - 36 405HIAA - 43 36 - 50 28

Table 8 Trends in analyticalperformance observed over athree year period

Trend Analyte

1

2

3

4

5

Consistent improvement over Calciumthree yearsSteady progress over three Potassium, osmolalityyearsImprovement from 1981 to Urea, creatinine1982, which has been maintainedImprovement from 1982 to Sodium, phosphate, glucose,1983 chloride, oxalate, 51lAAConsistent decline over Proteinsthree years

ory error, as defined in Table 3, have been used foreach survey. We therefore consider that the percen-tage of unacceptable results represents an appropri-ate parameter to observe trends in overall analyticalperformance over the three year period. The per-centages of unacceptable results submitted for allparticipating laboratories and for the selected groupof 47 laboratories that have participated in all threeurine surveys are shown in Table 7. The trends inanalytical performance observed, which are similarfor all laboratories compared with the group of 47laboratories that participated in all three surveys,are summarised in Table 8.

Table 9 summarises the conclusions concerningoverall analytical performance, as at 1983, based onthe premise that the findings in 1983 reflect culmina-tion of three years work towards improved analyti-cal performance and the criteria that (a) <15% of

unacceptable results indicates that an analysis is per-formed satisfactorily, (b) 15-35% of unacceptableresults indicates that analysis requires furtherimprovement, and (c) that >35% of unacceptableresults indicates that analysis is performed poorly.As a direct consequence of the results obtained inthe Australasian urine programme, working partieshave been established in 1983 by the Scientific andTechnical Committee of the Australian Associationof Clinical Biochemists with the specific aim ofimproving the performance of both urinary oxalateand HMMA analyses.The overall data obtained over three years con-

cerning the imprecision and bias of each analyte sur-veyed are shown in Tables 10 and 11. The medianimprecision and bias obtained by all laboratories,the imprecision and bias obtained by the top 10% ofall participating laboratories, and the median impre-cision and bias obtained by the 47 laboratories par-ticipating in all three surveys is provided. Themedian value is considered to reflect "average"laboratory performance. As detailed earlier, sincethe range of analyte concentrations for the urinesurvey samples has been very different from one

year to the next, imprecision and bias are expressednot only in absolute terms but also as coefficientsof variation (CV%) and coefficients of bias (CB%)respectively, such terms being defined as:

CV =

CB =

SD

Midpoint of analyte concentration range

Bias

x 100%

x 100%Midpoint of analyte concentration range

Analytical goals for the imprecision of 10 of theurinary analytes surveyed have been derived by anumber of approaches.6 The most stringent analyti-cal goals obtained from such approaches are shownfor each analyte in Table 12. Stevens and Cress-well'0 have previously advocated that the impreci-sion, expressed as one standard deviation, achievedby the top 10% of participating laboratories shouldbe used as a target for imprecision for alllaboratories. By comparing the standard of impreci-sion achieved by the top 10% of laboratories (Table10) with the analytical goals, it can be seen that theanalytical goals can be achieved, and in someinstances have been surpassed, by this group oflaboratories for urine sodium, potassium, osmolal-

Table 9 Standard ofanalytical performance, based on 1983 findings

Criterion Comment Analyte

<15% unacceptable results Perform satisfactorily Sodium, potassium, creatinine, phosphate, glucose, chloride15-35% unacceptable results Require further improvement Osmolality, urea, calcium>35% unacceptable results Require substantial improvement Proteins, oxalate, 5HIAA, HMMA, urate

>

>

Table 10 Imprecision obtained over three years in Australasian urine programme

Analyte Median imprecision of all laboratories Median imprecision of47 laboratories Top 10% imprecision of all laboratories

SD CV SD CV SD CV

1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983

Sodium (mmol/l) 2-8 3-9 1-4 1-7 2-1 2-1 2-6 3-9 1-5 1-6 2-1 2-2 1-1 0 9 0-6 0 7 0-5 0 9Potassium (mmol/1) 1-1 0-8 1-4 1-6 2-0 2 5 1-0 1-0 1-4 1-5 2 5 2 5 0-7 0-3 0-4 1-0 0-8 0-7Osmolality (mmol/kg) 9-8 7-6 5*8 1.0 1-0 1-2 9-8 5-4 5 8 1-0 0-7 1-2 4-2 2-6 2-5 04 04 05Urea (mmol/1) 25-3 11-0 13-8 5-5 4-4 5-6 23 5 11-0 13-9 5-1 4-4 5-7 7-2 3-7 4-8 1-6 1-5 2-0Creatinine (mmol/1) 0-68 0-29 0-44 4-4 3-2 4-2 0-66 0-30 0-41 4-3 3-3 3-9 0-3 0-1 0-1 1-9 1-3 1-1Calcium (mmol/1) 0-33 0-07 0-09 5-8 4-4 3-7 0-35 007 0-10 6-1 4-4 4-1 0-1 0-02 0-03 1-8 1-3 1-2Phosphate (mmol/1) 1-36 1-06 1-05 5-2 5.3 9-4 1-19 1-35 085 4-6 6-8 7-6 0-5 0-4 0-3 1-9 1-9 2-9Urate (mmol/1) 0-15 0-07 0-48 13-6 8-8 23-5 0-14 0-07 052 12-7 8-8 25-5 0-04 0-02 0-16 3-6 2 5 7-8Proteins (g/l) 0-10 0*04 0-11 7-9 9-3 11-1 0-10 0 03 0-09 7-9 7-0 9-1 0 04 0-01 0-04 3-2 2-3 4 0Glucose (mmol/1) 0-1 0-5 0-4 0-8 3-4 4-3 0-1 0-5 0-3 0-8 3.4 3-3 0-02 0-21 0-15 0-2 1-5 1-6Chloride (mmol/1) - 27 1-6 - 1-6 2-1 - - - - - - - 1-2 0-52 - 0-7 0-7Oxalate (mmoll1) - 0-03 0-05 - 12-9 15-5 - - - - - - - 0-01 0-02 - 4-8 6-9HMMA (,Urmol/1) - 10-3 13-8 - 13-2 18-2 - - - - - - - 3-9 4-7 - 5 0 6-25HIAA (AmoVl) - 12-6 13-3 - 14-7 12-4 - - - - - - - 2-4 5-8 - 2-8 5 4

SD = standard deviation.CV = coefficient of variation.

Table 11 Bias obtained over three years in Australasian urine programme

Analyte Median bias of all laboratories Median bias of47 laboratories Top 10% bias of all laboratories

Bias CB Bias CB Bias CB

1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983

Sodium (mmol/1) 3-8 6-1 2-0 2-3 3-2 2-9 3-7 6-0 2-0 2-3 3-2 2-9 1-4 1-3 0-6 0 9 0-7 0-8Potassium (mmol/1) 1-7 1-5 1-5 2-5 3-8 2-7 1-2 1-6 1-3 1-8 4 0 2-4 0-6 0-6 0-2 0-9 1-4 0-4Osmolality (mmol/kg) 15-8 18-5 7-5 1-7 2-5 1-5 17-3 15-3 7-3 1-8 2-1 1-5 7-7 4-3 2-4 0-8 0-6 0-5Urea (mmoil1) 25-8 12-5 11-0 5-6 5-0 4 5 25 8 10-0 10-1 5-6 4-0 4-1 8-3 4-6 4-4 1-8 1-8 1-8Creatinine (mmol/1) 1-19 0-41 0-60 7.7 4.5 57 1-06 033 0-38 6-8 3-6 3-6 0-29 0-12 0-09 1-9 1-3 09Calcium (mmol/1) 0-54 0-11 0-10 9-5 6-9 4-1 0-58 0-10 0-11 10-2 6-3 4 5 0-11 0-03 0-03 1-9 1-8 1-2Phosphate (mmol/1) 1-70 1-36 095 6 5 6-8 8-5 1-48 1-35 0-69 5-7 6-8 6-2 0-42 0-38 0-28 1-6 1-9 2-5Urate (mmol/1) 0-29 0-21 0-48 26-4 26-3 23-5 0-28 0-22 0-51 25-5 27-5 25 0 0-06 0-06 0-21 5.5 7-5 10-3Proteins (gil) 0-22 0-08 0-13 17-3 18-6 13-1 0-18 0-7 0-12 14-2 16-3 12-1 0 04 0-02 0-05 3-1 4-7 5-1Glucose (mmol/l) 0-7 1-3 0-3 5-8 9-0 3-3 1-0 1-0 0-2 8-3 6-9 2-2 0-10 0-21 0-11 0-8 1-4 1-2Chloride (mmolI1) - 4-8 2-0 - 2-8 2-6 - - - - - - - 13 0-6 - 0-8 0 7Oxalate (mmolIl) - 0.05 007 - 22-4 24-5 - - - - - - - 0.01 0-02 - 3-8 6-9HMMA (,umol/1) - 12-1 20-0 - 15-5 26-3 - - - - - - - 440 4.7 - 5-1 6-2SHIAA (,umoIIl) - 19-0 16-0 - 22-1 15-0 - - - - - - - 3-3 6-4 - 3-8 6-0

Table 12 Analytical goals for the imprecision ofquantitative urine analyses

Analyte Analytcal goal

Sodium (mmol/1) 0-7Potassium (mmoVI) 0 5Osmolality (mmollkg) 2 5Urea (mmoVI) 3-6Creatinine (mmoVI) 0-4Calcium (mmoVl) 0-1Phosphate (mmoVI) 0 7Urate (mmol/1) 0-1Proteins (gil) 0-01Glucose (mmol/l) 0-06

ity, creatinine, calcium, and phosphate. Further-more, imprecision, in SD terms, has continued toimprove for urine sodium, osmolality, and phos-phate.Over the three year period more than 5% of

results submitted were classed as blunders, in at

least two of the three years, for the analyses ofosmolality, urea, calcium, urate, proteins, oxalate,and 5HIAA. As well as being due to inherently pooranalytical technique, blunders were mainly attri-buted to transcription, dilution, or calculation mis-takes. For osmolality we recommend that attentionshould also be paid to calibration with a materialwhich has an analyte concentration similar to that ofroutine urine specimens. For urate it was evidentthat some laboratories were not aware that urateprecipitates in an acidic urine and, as a result, didnot take the preanalytical precaution of alkalinisingurine specimens submitted for urate analysis."

COMPARISON OF INDIVIDUAL METHODS FOREACH ANALYTEA critical assessment of the suitability of individualmethods for routine laboratory use has beenattempted using the data summarised in Table 13.

Shephard, Penberthy, Fraser420

Evolution of a national urine quality assurance programme: the Australasian experience, 1981-1983 421

Table 13 Comparative performance ofindividual methods

Analyte Method No of Results Percentage Imprecision Biaslaboratories submitted unacceptable (median SD of (median bias of

all laboratories) anl laboratories)

1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983 1981 1982 1983

AllSodium Flame photometry-direct

Flame-continuous flowIon selective electrode

AllPotassium Flame photometry-direct

Flame-continuous flowIon selective electrode

AllOsmolality Freezing point depression

KnauerFiskeAdvancedOsmette

Vapour pressure

AllUrea Diacetyl monoxime

UreaseUrease/conductivity

AllCreatinine Jaffe-kinetic

Jaffe-end point

AllCalcium Cresolphthalein complexone

Methyl thymol blueAtomic absorptionCorning titratorCalcette titrator

AllPhosphate Phosphomolybdovanadate

Phosphomolybdate reduction

AllUrate Phosphotungstate reduction

UricaseMetal complex reduction

AllTCA/ponceau STCA/biuret

Proteins SSA/biuretSSA turbidimetryTCA turbidimetryCoomassie blue

AllGlucose Glucose oxidase

HexokinaseO2 rate-Beckman°2 rate-Yellow SpringsAll

Chloride Silver titrationMercury titrationThiocyanate/nitrate

Oxalate All

AllHMMA Oxidation to vanillin

p-nitroaniline

AllSHIAA Nitrosonaphthol

82 9159 619 87 16

82 9159 629 87 16

58 60

9 911 1224 205 86 8

70 7436 3220 273 5

83 9039 4538 33

79 8130 334 8

27 2611 82 4

75 758 5

60 64

77 8231 2838 46

1 1

80 9617 155 44 422 2520 195 6

44 449 136 107 115 2

- 57- 35

98

- 12

- 32- 18

4

- 30- 22

94419

32

94419

32

64

11279S

7631249

964633

91349

23123

82S

67

862649

931871

171612

45710122

5729

9

17

40197

3423

916 485 510 8656 320 214 996 47 50 980 85 180 1

918 486 508 7656 325 214 698 47 50 2180 85 178 3

622 311 347 30

100 43 26 39112 56 59 32263 117 146 2352 47 52 1464 35 30 28

741 384 391 45382 170 166 45227 140 121 5032 30 52 28

922 478 514 17436 236 251 17422 177 177 16

858 427 488 51325 176 182 6044 42 53 71287 132 124 50112 41 65 2520 22 14 35

771 394 433 2596 24 26 12

603 341 357 25

890 421 436 38392 149 136 24418 236 249 52

4 6 - 75

848 452 488 37186 86 95 2556 22 40 3946 23 6 44213 126 79 41211 103 91 3960 30 61 25

355 229 229 1365 72 42 265 51 50 267 66 67 251 12 10 37

- 228 273 -

- 172 153 -

41 - -

- 42 42 -

- 52 80 -

- 142 204 -

- 80 105 -

- 20 36 -

- 150 168 -

- 115 116 -

17181514

109

1513

30

4934152663

27213233

463

253719181214

263826

37234583

39192726782420

211329218

146

2236

62

393625

4344

64126

1296

15

25

3831151363

28263319

11146

22291721140

151215

828282

54437050755749

45

210

3

10

48

413050

3638

2-8 3-9 1-4 3-8 6-1 2-030 39 1-0 4-2 6-1 2-03-2 3-6 1-5 3-7 6-2 1-32-3 1-2 1-6 1-5 34 1-9

1-1 0-8 1-4 1-7 1-5 1-51-3 0-8 1-2 1-1 1-3 1-43-9 1-0 1-4 3-3 1-3 1-80-9 0-8 1-6 1-5 2-1 1-4

9-8 7-6 5-8 15-8 18-7 7 5

15-9 9-0 - 15-7 19-0 -

13-5 9 3 5-8 23-1 24-7 7-18-1 4-2 5-0 13-4 10-1 6-64-6 7-1 4-3 14-1 18-6 6-210-6 10-0 9-6 14-4 27-3 12-2

25-3 11-0 13-8 25-8 12-5 11-025-5 10-7 11-8 23-3 10-0 9-228-6 15-3 22-0 32-3 12-2 21-9- 26-5 10-2 - 12-2 9-8

0 68 0-29 0 44 1-19 0-41 0-600-61 0-29 0-42 1-25 0-50 0-610-71 0-32 0-42 1-13 0-37 0.50

0-33 0-07 0-09 054 0-11 0-100 39 0-09 0-16 0-62 0-18 0-14- 0-05 0-10 - 0-12 0-070 30 0-05 0-08 0-80 0-10 0-110-13 0-04 0-04 0-38 0-03 0-09

1-36 1-06 1-05 1-70 1-36 0-950-96- - 1-02- -

1-34 0-96 1-05 1-73 1-31 0-83

0-15 0-07 0-48 0-29 0-21 0-480-17 0-09 0-39 0-15 0-12 0-500-14 0-05 0-54 0-39 0-25 0-46

0-10 0-04 0-11 0-22 0-08 0-130-14 0-03 0-08 0-21 0-06 0-090-05 - 0-12 0-11 - 0-190-06- - 0-22- -

0-12 0-04 0-14 0-46 0-23 0-310-10 0-04 0-10 0-32 0-07 0-130-15 0-01 0-18 0-10 0-06 0-14

0-1 0-5 0-4 07 1-3 030-1 0-4 0-3 0-7 1-2 0-30-1 0-7 0-2 0-3 0-9 0-30-1 0-5 0-4 0-3 1-4 0-30-5 - - 0-6 - -

- 2-7 1-6 - 4-8 2-0- 2-2 1-4 - 3-4 1-8- 2-7 - - 8-1 -

- 4-2 2-2 - 8-3 1-4

- 0-03 0-05 - 0-05 0-07

- 10-3 13-8 - 12-1 20-0- 11-9 12-8 - 19-4 16-2- - 8-2 - - 24-1

- 12-6 13-3 - 19-0 16-0- 12-4 12-3 - 20-3 17-0

The number of laboratories and results submitted do not add up to the respective totals, owing to the fact that "misceilaneous" methods for each analyteare not included in the table.TCA = trichloroacetic acid.SSA = sulphosalicyclic acid.

422

Table 14 Methods with poor and betterperformance,assessed by the percentage ofunacceptable results

Analyte Method

Methods with poor perfornanceOsmolality Freezing point depression-Knauer

Vapour pressure-WestcorCalcium Cresophthalein complexoneUrate UricaseProteins TCA-biuret

SSA-biuretTCA-turbidimetry

Oxalate All methods5HIAA Nitrosonaphthol

Methods with good performanceSodium Flame photometry-direct

Ion selective electrodePotassium Flame photometry-directCreatinine Jaffe-end pointGlucose Glucose oxidase

Hexokinase0 rate-Beckman

Chloride Silver titration

For abbreviations see Table 13.

Table 15 Methods with poor and good performancecharacteristics, assessed by median imprecision and bias

Analyte Method

Poor imprecision and poor biasOsmolality Vapour pressure-WestcorUrea UreaseCalcium Cresolphthalein complexone

Good imprecision and good biasCalcium Coming titratorProteins TCA/Ponceau S

Poor imprecision (only)Chlonde Thiocyanate/nitrate

Poor bias (only)Osmolality Fiske osmometerProteins SSA turbidimetry

Good imprecision (only)Osmolality Osmette osmometer

Good bias (only)Sodium Ion selective electrodeUrate Phosphotungstate reductionGlucose Hexokinase

Poor imprecision but good biasProteins Coomassie blue

For abbreviations see Table 13.

Two methods-namely, metal complex reductionfor the analysis of urinary urate and sulphosalicyclicacid turbidimetry for urine protein assay-are con-

sidered to be unsuitable for routine urine analyses.These two methods have, for two years in succes-

sion, had more than 70% of results submitted out-side the allowable limits of error. Metal complexreduction was accordingly discontinued in the 1983urine survey. In 1982 the high level of unacceptableresults for the sulphosalicyclic acid turbidimetricmethod was considered to reflect the fact that the

Shephard, Penberthy, Fraser

survey material, in that year, contained a smallamount of bovine albumin. The continued high levelof unacceptable results recorded by this method in1983 using a totally human based matrix, however,raises serious doubts as to the validity of this methodfor routine analytical purposes.Methods assessed as having shown poor perfor-

mance and good performance, using the criterionthat the percentage of unacceptable results, for atleast two out of three years, was >35% or <10%respectively, are shown in Table 14.Table 13 also shows the median imprecision and

bias for individual methods. Such data were calcu-lated for those method groups in which 36 or moreresults were submitted in a particular year. Themedian value was chosen, again, since it was consi-dered to reflect the "average" performance of anindividual method group. For the reasons outlinedearlier in this paper, it is difficult to draw conclusionson the comparative performance of methods interms of trends over a three year period. By compar-ing the differences in magnitude of the imprecisionand bias, expressed in absolute terms, between indi-vidual methods within a given year, however, objec-tive conclusions are possible.Methods considered to show poor and good per-

formance characteristics, in terms of imprecisionand bias, are listed in Table 15. The criterion usedfor classifying methods into these categories wasthat if the median imprecision or bias or both of aparticular method was 25% better (or worse) thanthe " all method" median imprecision or bias or bothfor a particular analyte for at least two out of thethree years, then that particular method was deemedto display good (or poor) imprecision or bias or bothrespectively.Throughout the Australasian urine quality assur-

ance programme individual participants have beenurged to examine critically the summary of their per-formance and assess the imprecision, inaccuracy,and linearity of their methods. At the end of thethird year the survey organisers believed that thewealth of data generated from these surveys shouldbe summarised in a manner which all laboratoriescould use positively to achieve a generally higherstandard of performance in the future. We hope thatthis report facilitates this aim.

References

'Glenn GC, Hathaway, TK. Urine chemistry: a new CAP pro-gram. Am J Clin Pathol 1977;68:153-8.

2 Glenn GC. The CAP urine chemistry survey program for 1977.Am J Clin Pathol 1978;70:513-5.

Evolution of a national urine quality assurance programme: the Australasian experience, 1981-1983 423

3Glenn GC. Evolution of the urine chemistry survey program ofthe CAP. Am J Clin Pathol 1979;72:299-305.

Shephard MDS, Penberthy LA, Fraser CG. Analytical goals forquantitative urine analysis. Pathology 1981;13:543-6.

s Shephard MDS, Penberthy LA, Fraser CG. A quality assuranceprogramme for quantitative urine analyses. Pathology1982;14:327-31.

6Shephard MDS, Penberthy LA, Fraser CG. The 1982Australasian programme for quantitative urine analysis. ClinBiochem Revs 1983;3:128-32.

7Shephard MDS, Penberthy LA, Fraser CG. The 1983Australasian programme for quantitative urine analysis. ClinBiochem Revs (in press).

8Bowyer RC, Geary TD, Penberthy LA, Thomas DW. AnAustralian quality control scheme for clinical chemistry. TheClinical Biochemist Newsletter 1981 ;60:43-9.

Westgard JO. Precision and accuracy: concepts and assessmentby method evaluation testing. CRC Crit Revs Clin Lab Sci1981;13:283-330.

'0 Stevens JF, Cresswell MA. Achievable standards of laboratoryperformance. News Sheet. Associaton of Clinical BiochemistsLtd 1978;182: 12-3.

Shephard MDS, Mazzachi RD. The collection, preservation,storage and stability of urine specimens for routine clinicalbiochemical analysis. Clin Biochem Revs 1983;4:61-7.

Requests for reprints to: Mr MDS Shephard, Departmentof Clinical Biochemistry, Flinders Medical Centre, Bed-ford Park, South Australia 5042, Australia.