Traceability Assessment and Performance Evaluation of Results for Measurement of Abbott Clinical Chemistry Assays on 4 Chemistry Analyzers

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1 Trceility Assessment nd Performnce Evlution of Results for Mesurement of Aott Clinicl Chemistry Assys on 4 Chemistry Anlyzers Jinsook Lim, MD; Kyung Eun Song, MD, PhD; Sng Hoon Song, MD, PhD; Hyun-Jung Choi, MD, PhD; Sun Hoe Koo, MD, PhD; Gye Choel Kwon, MD, PhD Context. The trceility of clinicl results to interntionlly recognized nd ccepted reference mterils nd reference mesurement procedures hs ecome incresingly importnt. Therefore, the estlishment of trceility hs ecome mndtory requirement for ll in vitro dignostics devices. Ojectives. To evlute the trceility of the Aott Architect c8000 system (Aott Lortories, Aott Prk, Illinois), consisting of clirtors nd regents, cross 4 different chemistry nlyzers, nd to evlute its generl performnce on the Toshi 2000FR NEO (Toshi Medicl Systems Corportion, Otwr-shi, Tochigi-ken, Jpn). Design. For ssessment of trceility, secondry reference mterils were evluted 5 times, nd then is ws clculted. Precision, linerity, nd crryover were determined ccording to the guidelines of the Clinicl nd Lortory Stndrds Institute (Wyne, Pennsylvni). Results. The ises from 4 different nlyzers rnged from 2.33% to 2.70% on the Toshi 2000FR NEO, 2.33% to 5.12% on the Roche Hitchi 7600 (Roche Dignostics Interntionl, Bsel, Switzerlnd), 0.93% to 2.87% on the Roche Modulr, nd 2.16% to 2.86% on the Aott Architect c The totl coefficients of vrince of ll nlytes were less thn 5%. The coefficients of determintion (R 2 ) were more thn The crryover rte rnged from 0.54% to 0.17%. Conclusions. Aott clinicl chemistry ssys met the performnce criteri sed on desirle iologicl vrition for precision, is, nd totl error. They lso showed excellent linerity nd crryover. Therefore, these clinicl chemistry ssys were found to e ccurte nd relile nd re redily pplicle on the vrious pltforms used in this study. (Arch Pthol L Med. 2016;140: ; doi: / rp oa) Clinicl lortories hve pivotl roles in clinicl decisions regrding the dignosis, risk ssessment, tretment, nd monitoring of ptients. 1 Thus, the methods used for dignostic mesurements must e ccurte, precise, specific, nd comprle mong lortories. Otherwise, indequte or incorrect nlytic performnce cn led to potentilly serious consequences for ptients, clinicins, nd ultimtely the entire helth cre system. 2 However, even common clinicl-chemistry nlytes hve een shown to demonstrte prolems with comprility, exhiiting uncceptle or suoptiml is in comprison to the true vlue, Accepted for puliction August 5, From the Deprtment of Lortory Medicine, Chungnm Ntionl University Hospitl, Dejeon, South Kore (Drs Lim, Koo, nd Kwon); the Deprtment of Lortory Medicine, Kyungpook Ntionl University Hospitl, Degu, South Kore (Dr K.E. Song); the Deprtment of Lortory Medicine, Seoul Ntionl University Hospitl nd College of Medicine, Seoul, South Kore (Dr S.H. Song); the Deprtment of Lortory Medicine, Chonnm Ntionl University Hospitl, Gwngju, South Kore (Dr Choi). This study ws finncilly supported y Aott Dignostics (Aott Prk, Illinois). The uthors hve no other relevnt finncil interest in the products or compnies descried in this rticle. Reprints: Gye Choel Kwon, MD, PhD, Deprtment of Lortory Medicine, Chungnm Ntionl University Hospitl, 33 Munhw-ro, Joong-gu, Dejeon , South Kore (emil: kwon8004@gmil. com). s determined y reference method. 3 6 As consequence, emphsis hs incresingly een plced on the need for stndrdiztion or hrmoniztion of lortory tests. Trceility refers to n unroken chin of comprisons relting test result to the interntionl reference methods nd reference mterils. 2 To ensure tht mesurement results re comprle cross mesurement systems, loctions, nd time, the importnce of trceility hs ecome incresingly pprecited. 7 The estlishment of trceility in mesurements performed with in vitro dignostic devices ecme mndtory with the implementtion of the Europen Union directive on in vitro dignostic devices (Directive 97/79/EC). 7,8 In this study, the trceility of Aott clinicl chemistry ssys (Aott Lortories, Aott Prk, Illinois) ws evluted for 17 nlytes using commutle nd vluessigned, secondry reference mterils on sprtte minotrnsferse (AST), lnine minotrnsferse (ALT), c- glutmyltrnspeptidse (GGT), mylse, lood ure nitrogen (BUN), totl cholesterol, triglyceride (TG), low-density lipoprotein (LDL), high-density lipoprotein (HDL), glucose, cretinine, cretine kinse (CK), uric cid, clcium, phosphorus, iron, nd lctte dehydrogense (LDH). All ssys were evluted on 4 different nlyzing pltforms, including the Roche Hitchi 7600 (Roche Dignostics Interntionl, Bsel, Switzerlnd), the Roche Modulr (Roche), the Aott c16000 (Aott), nd the Toshi 2000FR NEO (Toshi Arch Pthol L Med Vol 140, My 2016 Trceility nd Performnce of Aott Assys Lim et l 467

2 Medicl Systems Corportion, Otwr-shi, Tochigi-ken, Jpn). In ddition, the nlyticl performnce of Aott clinicl chemistry ssys ws evluted on the Toshi 2000FR NEO for precision, linerity, nd crryover. MATERIALS AND METHODS Trceility Assessment Reference Mterils. Secondry reference mterils were purchsed from the Reference Mteril Institute for Clinicl Chemistry Stndrds (ReCCS, Kwski, Kngw, Jpn), which is n orgniztion whose purpose is developing nd issuing reference mterils. This orgniztion hs een pproved s n ccredited clirtion lortory y Interntionl Accredittion Jpn (Tokyo, Jpn) in the medicl field, meeting qulity requirements specified y the Interntionl Orgniztion for Stndrdiztion (ISO; Genev, Switzerlnd): ISO 17025, 9 ISO 15195, 10 nd ISO Guide The ReCCS certified reference mteril (JCCRM ) 12 smples were ssigned vlues for totl cholesterol, HDL, LDL, TG, cretinine, glucose, uric cid, BUN, clcium, phosphorus, nd iron y nlysis using isotope-dilution mss spectrometry methods or estlished reference methods. The JCCRM smple 12 ws prepred from humn pooled serum, which conforms with the Clinicl nd Lortory Stndrds Institute (CLSI; Wyne, Pennsylvni) 37-A guideline 13 for the preprtion of secondry cholesterol reference mteril. The Jpnese Committee for Clinicl Lortory Stndrds Certified Reference Mteril (JCCLS CRM- 001c) 14 is equivlent to the secondry clirtion mteril for metrologicl trceility defined in ISO The JCCLS CRM- 001c smples were ssigned trget vlues for AST, ALT, CK, LD, GGT, nd mylse y nlysis using Jpn Society of Clinicl Chemistry (JSCC; Kngw, Jpn) primry reference mesurement procedures. They were lyophilized from solution contining 8 kinds of humn nd recominnt-type enzymes nd provided in 2 concentrtions for totl cholesterol, LDL, HDL, nd TG. 16 Trceility Assessment. Ech reference mteril ws mesured 4 times, nd the men, stndrd devition, nd men is were clculted. Trceility ws tested sed on the totl llowle error with desirle qulity specifictions s descried y Frser. 17 Performnce Evlution Instrument, Clirtors, nd Regents. The Toshi 2000FR NEO ws used for the evlution of nlytic performnce for the Architect clinicl chemistry ssys with clirtors nd regents. All procedures were performed ccording to the mnufcturer s instructions. Precision. According to CLSI EP5-A2, 18 ssyed Lyphochek Chemistry Control (Bio-Rd Lortories, Hercules, Cliforni) levels 1, 2, nd 3 were mesured in duplicte twice dy for 20 dys. Totl precision nd within-run precision were ssessed. Linerity. Linerity ws evluted ccording to CLSI EP6-A. 19 Ptient smples with high nd low levels were used nd mixed per rtios of 4:0, 3:1, 2:2, 1:3, nd 0:4. Five totl levels of specimens were formulted nd mesured 4 times ech. Using the levels mesured nd estimted, liner-regression nlysis ws performed, nd the coefficient of determintion (R 2 ) ws clculted. Crryover. Ptient smples with high levels were mesured 4 times (H1, H2, H3, H4), nd ptient smples with low levels were mesured 4 times (L1, L2, L3, L4). The crryover rte ws clculted ccording to the following formul: L1 ðl3 ½ þ L4Þ=2Š Crryover rte ¼ ½ðH2 þ H3Þ=2Š ½ðH3 þ H4Þ=2Š Sttisticl Methods Sttisticl nlyses, including clcultions of the men, stndrd devition, coefficient of vrince (CV), within-run CV, etween-run CV, totl CV, nd R 2 were performed using Anlyse-it (version 2.30, Anlyse-it Softwre, Leeds, United Kingdom) with Excel 12þ (Microsoft, Leeds, United Kingdom). RESULTS Trceility Assessment All mesurement results for the 17 nlytes otined with Aott clinicl chemistry regents on 4 different pltforms re shown in Tle 1. All mesurements were within vlues specified y the reference mesurement procedures. The clculted men is nd totl llowle error re shown in Tle 2. Precision The clculted within-run nd totl CV (%) t 3 levels (1, 2, nd 3) for 17 chemistry nlytes re summrized in Tle 1. Totl CV for level 1 rnged from 1.2% to 5.1%; for level 2, from 1.0% to 7.1%; nd for level 3, from 1.0% to 4.5%. For ll nlytes, totl CV ws less thn 5% (Tle 3). Linerity For most of the nlytes, the R 2 rnged from to (Tle 4). Crryover For ll nlytes, the crryover ws less thn 0.6% (Tle 5). COMMENT The in vitro dignostic directive (Directive 97/79/EC), which ecme effective in Europe in 2003, requires mnufcturers to provide informtion out the trceility of their clirtors when requested. 20 Commercil methods using vlidted clirtors my yield vlues for ptient smples tht re trcele to the reference method vi n intermedite-trueness trnsfer using reference mteril, 21 which is the sic requirement of evidence-sed medicine. 7 In this study, the trceility of Aott clinicl chemistry ssys ws evluted not only on the Aott Architect system ut lso on other pltforms. This is necessity in South Kore, where universl nlytic pltforms with clirtors nd regents from different mnufcturers re commonly used. In this study, the dt sed on the components of iologicl vrition were used for the ssessment of precision, is, nd totl error, 17 s well s criteri proposed y professionl groups for nlytes, such s glucose, lipid profiles, nd cretinine. 4,22,23 All nlytes mesured using the Architect clinicl chemistry ssys yielded vlues within the rnges specified y reference mesurement procedures, except for HDL nd TG, when mesured on the Toshi 2000FR NEO (Tle 1). Therefore, the trceility of the metrologiclly higher-order reference method ws mintined cross different pltforms using the Aott clinicl chemistry ssys. Furthermore, pplying the desirle iologicl-vrition specifiction, 17 the clculted is nd totl error, which evlutes rndom error (imprecision) nd systemic error (inccurcy), respectively, hve met the criteri successfully for ll nlytes except clcium. Both is nd totl error were within the criteri only on the Toshi 2000FR NEO nd the Architect c16000 pltforms. For lmost ll nlytes, the Architect clinicl chemistry ssys showed cceptle results ccording to the guidelines estlished y experts. 4,22,23 In ddition, for glucose, 468 Arch Pthol L Med Vol 140, My 2016 Trceility nd Performnce of Aott Assys Lim et l

3 Tle 1. Anlytes Trceility Assessment of Aott Clinicl Chemistry Assys on 4 Different Anlytic Pltforms Trget Vlue (Uncertinties) Toshi 2000FR NEO, men Roche Hitchi, c men Roche Modulr, c men Aott Architect c8000, men Totl cholesterol, mg/dl (2.9) HDL, mg/dl (1.7) LDL, mg/dl 83.0 (3) TG, mg/dl 83.5 (2.1) Cretinine, mg/dl 0.92 (0.03) Glucose, mg/dl (2.0) Clcium, mg/dl 9.67 (0.19) Iron, lg/dl 93.0 (4) BUN, mg/dl (0.4) Uric cid, mg/dl 4.60 (0.08) Phosphorus, mg/dl 3.84 (0.16) Totl cholesterol, mg/dl (3.8) HDL, mg/dl 38.2 (1.1) LDL, mg/dl 139 (5) TG, mg/dl (3.4) AST, U/L 161 (4) ALT, U/L 155 (4) CK, U/L 434 (10) LDH, U/L 397 (8) GGT, U/L 152 (5) Amylse, U/L 348 (9) Aott Lortories, Aott Prk, Illinois. Toshi Medicl System Corportion, Otwr-shi, Tochigi-ken, Jpn. c Roche Dignostics Interntionl, Bsel, Switzerlnd. uric cid, nd enzymes, they performed more ccurtely. 5,21,24,25 Especilly for enzymes, the mesured vlues for CK, LDH, nd mylse were significntly different from the trget vlues for the Aott system ccording to Jnsen et l 5 who ssessed trceility for those enzymes on vrious pltforms. Bsed on our results, the mesurement ccurcy of the Aott enzyme ssys hs gretly improved. In the ssessment of is nd totl error in clcium mesurements, the Roche pltforms exceeded the desirle iologicl criteri nd met miniml iologicl criteri. Clcium levels re known to e tightly regulted within Tle 2. Clculted Men Bis nd Totl Allowle Error (TE) of Aott Clinicl Chemistry Assys on 4 Different Anlytic Pltforms Toshi 2000FR NEO Roche Hitchi c Roche Modulr c Aott Architect c8000 Anlytes Bis, % TE, % Bis, % TE, % Bis, % TE, % Bis, % TE, % Totl cholesterol, mg/dl HDL, mg/dl LDL, mg/dl TG, mg/dl Cretinine, mg/dl Glucose, mg/dl Clcium, mg/dl Iron, lg/dl BUN, mg/dl Uric cid, mg/dl Phosphorus, mg/dl Totl cholesterol, mg/dl HDL, mg/dl LDL, mg/dl TG, mg/dl AST, U/L ALT, U/L CK, U/L LDH, U/L GGT, U/L Amylse, U/L Aott Lortories, Aott Prk, Illinois. Toshi Medicl System Corportion, Otwr-shi, Tochigi-ken, Jpn. c Roche Dignostics Interntionl, Bsel, Switzerlnd. Arch Pthol L Med Vol 140, My 2016 Trceility nd Performnce of Aott Assys Lim et l 469

4 Tle 3. Anlyte Smple Men Imprecision of 17 Aott Clinicl Chemistry Assys on Toshi 2000FR NEO Within-Run Precision Totl-Run Precision SD %CV SD %CV Mnufcturer s Climed %CV Allowle Imprecision, %CV AST, U/L Level Level Level ALT, U/L Level Level Level GGT, U/L Level Level Level Amylse, U/L Level Level Level Glucose, mg/dl Level Level Level Cretinine, mg/dl Level Level Level CK, U/L Level Level Level Iron, lg/dl Level Level Level Clcium, mg/dl Level Level Level Uric cid, mg/dl Level Level Level Phophorus, mg/dl Level Level Level Totl cholesterol, mg/dl Level Level Level TG, mg/dl Level Level Level HDL, mg/dl Level Level Level LDL, mg/dl Level Level Level BUN, mg/dl Level Level Level LDH, U/L Level Level Level Aott Lortories, Aott Prk, Illinois. Toshi Medicl System Corportion, Otwr-shi, Tochigi-ken, Jpn. the ody, nd their intrindividul nd interindividul vritions tend to e low (1.9% nd 2.8%, respectively), 17 resulting in strict precision nd ccurcy requirements. It hs een estimted tht n nlytic is of only mmol/l for clcium could increse the cost of ptient cre. 26 Thus, further vlidtion on the ccurcy of clcium mesurement is wrrnted. For precision, Aott clinicl chemistry ssys showed totl CVs of less thn 5%, which is less thn those of the mnufcturer s clims. Almost ll nlytes met the criteri set y the desirle iologicl vrition specifiction. Level 1 (3.7%) nd level 3 (3.6%) for glucose nd level 1 (2.8%) nd level 2 (2.8%) for cretinine slightly exceeded the trget criteri of 3.3% nd 2.2%, respectively. For glucose, the Americn Dietes Assocition (Crystl City, Virgini) suggests n nlytic precision gol of 2.9%. 22 Imprecision of glucose level 2 ws within these strict criteri, indicting tht this glucose ssy cn e suitle in screening for dietes ecuse this level is importnt for clinicl decision. For cretinine, the totl CV ws higher thn tht previously 470 Arch Pthol L Med Vol 140, My 2016 Trceility nd Performnce of Aott Assys Lim et l

5 Tle 4. Anlyte Linerity of Aott Clinicl Chemistry Assys on the Toshi 2000FR NEO Using Ptient Smples Liner Rnge Specified y the Mnufcturer Test Rnge Slope Y Intercept R 2 AST, U/L ALT, U/L GGT, U/L Amylse, U/L Glucose, mg/dl Cretinine, mg/dl CK, U/L Iron, lg/dl Clcium, mg/dl Uric cid, mg/dl Phosphorus, mg/dl Totl cholesterol, mg/dl TG, mg/dl HDL, mg/dl LDL, mg/dl BUN, mg/dl LDH, U/L Aott Lortories, Aott Prk, Illinois. Toshi Medicl System Corportion, Otwr-shi, Tochigi-ken, Jpn. reported (totl CV of 1.6%). 27 Considering tht in vitro dignostics mnufcture is required to improve precision levels t 1.00 mg/dl, nlytic precision of this ssy needs further vlidtion nd improvement, lthough totl error ws within the Ntionl Kidney Disese Eduction Progrm (Bethesd, Mrylnd) criteri. 4 In the ssessment of linerity, the R 2 for ll nlytes ws more thn 0.99, within the cliniclly meningful rnge. However, the linerity of ALT, GGT, nd TG ws verified outside the rnge climed y the mnufcturer. All nlytes showed less thn 0.2% of crryover. Bsed on criterion of 1%, cross-contmintion from specimens with high concentrtions seems to e miniml. 28 Tle 5. Crryover of Aott Clinicl Chemistry Assys on the Toshi 2000FR NEO Anlyte High Low Crryover, % AST, U/L ALT, U/L GGT, U/L Amylse, U/L Glucose, mg/dl Cretinine, mg/dl CK, U/L Iron, lg/dl Clcium, mg/dl Uric cid, mg/dl Phosphorus, mg/dl Totl cholesterol, mg/dl TG, mg/dl HDL, mg/dl LDL, mg/dl BUN, mg/dl LDH, U/L Arevitions: ALT, lnine minotrnsferse; AST, sprtte minotrnsferse; BUN, lood ure nitrogen; CK, cretine kinse; GGT, c- glutmyltrnspeptidse; HDL, high-density lipoprotein; LDH, lctte dehydrogense; LDL, low-density lipoprotein; TG, triglyceride. Aott Lortories, Aott Prk, Illinois. Toshi Medicl System Corportion, Otwr-shi, Tochigi-ken, Jpn. In conclusion, Aott clinicl chemistry ssys met the performnce criteri sed on desirle iologicl vrition, excellent linerity, nd crryover on the Toshi 2000FR NEO. In ddition, the results were trcele to the reference-mesurement procedures. Finlly, on 4 different pltforms, totl error for lmost ll nlytes, except clcium, ws within the criteri of desirle iologicl vrition nd interntionl working groups, especilly for glucose, cretinine, nd lipid profiles. In summry, Aott clinicl chemistry ssys re relile nd ccurte nd cn redily e pplied to different nlytic pltforms. References 1. von Eckrdstein A, Roth HJ, Jones G, et l. Cos 8000 Modulr nlyzer series evluted under routine-like conditions t 14 sites in Austrli, Europe, nd the United Sttes. J L Autom. 2013;18(4): Muller MM. Trceility in lortory medicine. In: De Bievre P, Gunzler H, eds. Trceility in Chemicl Mesurement. Berlin Heidelerg: Springer; 2005: Armruster D. Mesurement trceility nd US IVD mnufcturers: the impct of metrology. Accredit Qul Assur. 2009;14(7): Myers GL, Miller WG, Coresh J, et l; Ntionl Kidney Disese Eduction Progrm Lortory Working Group. Recommendtions for improving serum cretinine mesurement: report from the lortory working group of the Ntionl Kidney Disese Eduction Progrm. Clin Chem. 2006;52(1): Jnsen R, Schumnn G, Bdenhuijsen H, et l. Trueness verifiction nd trceility ssessment of results from commercil systems for mesurement of six enzyme ctivities in serum: n interntionl study in the EC4 frmework of the Clirtion 2000 project. Clin Chim Act. 2006;368(1 2): Miller WG, Myers GL, Ashwood ER, et l. Stte of the rt in trueness nd interlortory hrmoniztion for 10 nlytes in generl clinicl chemistry. Arch Pthol L Med. 2008;132(5): Vesper HW, Thienpont LM. Trceility in lortory medicine. Clin Chem. 2009;55(6): Europen Communities. Directive 97/79/EC of the Europen Prliment nd of the Council of 27 Octoer 1998 on in vitro dignostic medicl devices. Officil J Eur Communities L ;41: Committee on Conformity Assessment. ISO/IEC 17025: Generl Requirements for the Competence of Testing nd Clirtion Lortories. Genev, Switzerlnd: ISO; Committee on Clinicl Lortory Testing nd In Vitro Dignostic Test Systems. ISO 15195: Lortory Medicine Requirements for Reference Mesurement Lortories. Genev, Switzerlnd: ISO; Committee on Reference Mterils. ISO Guide 34. Genev, Switzerlnd: ISO; Reference Mteril Institute for Clinicl Chemistry Stndrds. Working Reference Mteril for Lipids nd 5 Items in Lortory Medicine: JCCRM Kwski, Jpn: ReCCS; Ferury 5, Progressive nd Stle Reference Mteril for Lipids Mesurements; MRH1-131(R2)(E). Arch Pthol L Med Vol 140, My 2016 Trceility nd Performnce of Aott Assys Lim et l 471

6 13. Clinicl nd Lortory Stndrds Institute. C37-A: Preprtion nd Vlidtion of Commutle Frozen Humn Serum Pools s Secondry Reference Mterils for Cholesterol Mesurement Procedures; Approved Guideline. Wyne, PA: CLSI; Novemer Jpnese Committee for Clinicl Lortory Stndrds. Certificte of Anlysis: Humn multi-enzymes reference mteril JCCLSCRM 001c. Tokyo, Jpn. July 12, Committee on Clinicl Lortory Testing nd In Vitro Dignostic Test Systems. ISO 18153: In Vitro Dignostic Medicl Devices Mesurement of Quntities in Biologicl Smples Metrologicl Trceility of Vlues for Ctlytic Concentrtion of Enzymes Assigned Clirtors nd Control Mterils. Genev, Switzerlnd: ISO; Reference Mteril Institute for Clinicl Chemistry Stndrds. Hndook: use of certified reference mterils. Updted on July Accessed April 4, Frser CG. Biologicl Vrition: From Principles to Prctice. Wshington, DC: AACC Press; Clinicl nd Lortory Stndrds Institute. Evlution of Precision Performnce of Quntittive Mesurement Methods: Approved Guideline- Second Edition. Wyne, PA: CLSI; CLSI document EP5-A Clinicl nd Lortory Stndrds Institute. Evlution of the Linerity of Quntittive Mesurement Procedures: A Sttisticl Approch; Approved Guideline-Second Edition. Wyne, PA: CLSI; CLSI document EP6-A. 20. Armruster D, Miller RR. The Joint Committee for Trceility in Lortory Medicine (JCTLM): glol pproch to promote the stndrdistion of clinicl lortory test results. Clin Biochem Rev. 2007;28(3): Xi C, Liu O, Wng L, Xu G. Trueness ssessment for serum glucose mesurement using commercil systems through the preprtion of commutle reference mterils. Ann L Med. 2012;32(4): Scks DB, Arnold M, Bkris GL, et l; Ntionl Acdemy of Clinicl Biochemistry; Evidence-Bsed Lortory Medicine Committee of the Americn Assocition for Clinicl Chemistry. Guidelines nd recommendtions for lortory nlysis in the dignosis nd mngement of dietes mellitus. Dietes Cre. 2011;34(6):e61 e Wrnick GR, Kimerly MM, Wymck PP, Lery ET, Myers GL. Stndrdiztion of mesurements for cholesterol, triglycerides, nd mjor lipoproteins. L Med. 2008;39(8): Lee W, Chung HJ, Hnnestd U, et l. Trueness ssessment of Koren ntion-wide glucose proficiency testing. Clin Chem L Med. 2011;49(6): Jing Y, Liu O, Xu G. Assessment of the trueness nd inter-lortory precision of routine uric ssys using 4 frozen pooled serum smples mesured y the Jpn Society of Clinicl Chemistry s HPCL method. Ann L Med. 2014; 34(2): Gllher MP, Moley LR, Klee GG, Schryver P. Plnning Report 04.1: The Impct of Clirtion Error in Medicl Decision Mking. Githersurg, MD: Ntionl Institute of Stndrds nd Technology; My director/plnning/uplod/report04-1.pdf. Accessed Mrch 3, Pnteghini M; IFCC Scientific Division. Enzymtic ssys for cretinine: time for ction. Clin Chem L Med. 2008;46(4): Broughton PM. Crry-over in utomtic nlyzers. J Automt Chem. 1984; 6(2): Arch Pthol L Med Vol 140, My 2016 Trceility nd Performnce of Aott Assys Lim et l