원저 Lab Med Online Vol. 7, No. 3: 135-14, July 217 임상화학 아미노말단풋뇌나트륨이뇨펩티드현장검사장비 Samsung LABGEO PA CHF Test 의성능평가 Performance Evaluation of a Point-of-care Test, Samsung LABGEO PA CHF Test, for the Amino-terminal Pro-brain Natriuretic Peptide 김만진 1,2 이경훈 1,3 전선희 3 송상훈 1,2 송운흥 4 송정한 1,3 Man Jin Kim, M.D. 1,2, Kyunghoon Lee, M.D. 1,3, Sun-Hee Jun, M.T. 3, Sang Hoon Song, M.D. 1,2, Woon Heung Song, Ph.D. 4, Junghan Song, M.D. 1,3 서울대학교의과대학검사의학교실 1, 서울대학교병원진단검사의학과 2, 분당서울대학교병원진단검사의학과 3, 신한대학교보건과학대학임상병리학과 4 Department of Laboratory Medicine 1, Seoul National University College of Medicine, Seoul; Department of Laboratory Medicine 2, Seoul National University Hospital, Seoul; Department of Laboratory Medicine 3, Seoul National University Bundang Hospital, Seongnam; Department of Biomedical Laboratory Science 4, Shinhan University, Uijeongbu, Korea Background: The amino-terminal pro-brain natriuretic peptide (NT-proBNP) is a useful biomarker for the diagnosis of acute congestive heart failure. A point-of-care test (POCT) could rapidly detect the presence of NT-proBNP during emergencies. We evaluated the analytical performance of the new Samsung LABGEO PA CHF Test (Samsung Electronics, Korea). Methods: Based on the guidelines of the Clinical and Laboratory Standards Institute (CLSI), we compared the precision, linearity, and method with those of the E17 (Roche Diagnostics, Switzerland). Matrix comparison between the NT-proBNP values in whole blood and plasma was also performed, and the reference interval was determined using residual samples from healthy adults selected based on the evaluation criteria. Results: The Samsung LABGEO PA CHF Test provided results in approximately 18 min. The coefficient of variation (CV) of within-laboratory precision was below 6.8%. A desirable linearity was observed in the range of 1, pg/ml, with R 2 =.99. The correlation with E17 was also excellent (N=18, r=.96). NT-proBNP values in the whole blood were correlated with those in the plasma (N=36, r=.99). The reference interval for the circulating NT-proBNP concentration was determined in 118 plasma samples from healthy subjects (26-75 yr of age). The 97.5th percentile was found to be 58.3 pg/ml. Conclusions: The Samsung LABGEO PA CHF Test demonstrated a good analytical performance. It could be a powerful tool as a POCT for clinical practice, particularly during emergencies. Key Words: NT-proBNP, Point-of-care testing, Performance evaluation 서론 심부전은미국에서매년 5 만명이상새로진단되고, 매년 3 만 명이상사망하는중요한질환이며, 우리나라에서도인구고령화 Corresponding author: Junghan Song Department of Laboratory Medicine, Seoul National University Bundang Hospital, 82 Gumi-ro 173beon-gil, Bundang-gu, Seongnam 1362, Korea Tel: +82-31-787-7691, Fax: +82-31-787-415, E-mail: songjhcp@snu.ac.kr Received: October 5, 216 Revision received: October 27, 216 Accepted: October 28, 216 This article is available from http://www.labmedonline.org 217, Laboratory Medicine Online This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4./) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 와함께유병률이증가하고있어 215년에는 1.6% 에서 24년에는 3.35% 로 2배이상늘어날것으로예측된다 [1]. 울혈성심부전의증상은비특이적인경우가많아, 정확한진단에어려움이있다 [2]. 또한, 호흡곤란으로응급실에내원한환자의경우, 급성심근경색등다른심장및폐질환과의신속한감별진단이환자예후에많은영향을미친다 [3]. 뇌나트륨이뇨펩티드 (Brain natriuretic peptide, BNP) 는심실의압력과과부하에반응하여심근에서분비되는물질로민감하고특이한심부전표지자로알려져있다 [4]. BNP는 32개의아미노산으로구성된단백질로심근세포에서합성된전구물질인 probnp에서 N-terminal fragment ( 아미노말단풋뇌나트륨이뇨펩티드, NT-proBNP) 와함께분비된다 [5]. NT-proBNP는생물학적으로불활성이지만 BNP보다반감기가훨씬길어안정된생물학적표지자로사용될수있다 [4]. 현장검사의장점중의하나인신속한결과보고는심폐기계중 eissn 293-6338 www.labmedonline.org 135
환자실에입원기간을줄여불필요한비용발생을막고응급실입원기간을단축시키며전체병원비를감소시키는것으로보고되었다 [3, 6]. 현재 NT-proBNP를측정하는현장검사장비로 Alere Triage NTproBNP (Alere, San Diego, CA, USA) 와 PATHFAST TM NT-proBNP (Mitsubishi Kagaku Iatron Inc, Tokyo, Japan) 등이쓰이고있다. 언급한키트는전혈을사용할수있지만검체종류에따른결과값의변동이컸다 [7]. 새로개발된 Samsung LABGEO PA CHF Test (Samsung Electronics, Suwon, Korea) 는원심방식임상화학자동분석장치로서, 전혈을사용하여울혈성심부전표지자인 NT-proBNP 측정용디스크로빠른시간내에안정적으로측정값을정량적으로알수있어, 상기질환을조기에진단하는데에도움을줄수있는현장검사장비이다. 따라서본연구에서는 Samsung LABGEO PA CHF Test의 NT-proBNP에대한검사분석능을평가하고중앙검사실장비와비교하여진단적유용성을확인하고자하였다. 2) 직선성평가직선성의평가를위해잔여검체중낮게나온검체와높게나온검체를이용하여 CLSI EP6-A 지침 [9] 에따라저농도 (L),.75L+.25H,.5L+.5H,.25L+.75H, 고농도 (H) 로희석하여 5개농도의검체를제조하여각농도별검체에대하여 5번반복측정하여총 25회검사하였다. 선형회귀분석및다항회귀분석을시행하였으며, nonlinearity 허용정도는 1% 이었다. 3) 상관성평가상관성평가는CLSI EP9-A3 지침 [1] 에따라동일한날에 E17과 Samsung LABGEO PA CHF Test 에서각각 2번측정한결과값을비교하였다. E17의분석측정범위 (5 35, pg/ml) 안에들어가는기보고된값을기준으로하여 3 pg/ml 미만의값을가지는 36개검체, 3 1, pg/ml 값을가지는 36개검체, 1, 5, pg/ml 값을가지는 36개검체로총 18개잔여검체를사용하였다. 대상및방법 1. 대상검체 분당서울대학교병원진단검사의학과로 NT-proBNP 검사가진행된후남아있는혈장잔여검체와동일인의전혈잔여검체, 제조사의전용정도관리물질을사용하였다. 본연구는분당서울대학교병원임상시험심사위원회 (IRB) 승인을얻었다 (B-123/147-31). 2. 대상장비 Samsung LABGEO PA CHF Test 는원심방식을사용하는임상화학자동분석현장검사장비로서전처리과정없이전혈검체를사용하여형광면역측정법 (fluorescence immunoassay) 으로 NTproBNP를 2분안에정량적으로분석할수있는장비이다. 총 2대기기와동일로트카트리지 (173-21-1) 를사용하여모든평가를진행하였으며, 상관성평가를위해현재검사실에서사용하고있는 E17 (Roche Diagnostics, Basel, Switzerland) 와비교평가하였다. 3. 평가방법 1) 정밀도평가제조사에서제공한두종류의정도관리물질 (153 pg/ml, 1,5 pg/ml) 을이용하여 Clinical Laboratory Standards Institute (CLSI) EP5-A3 지침 [8] 에따라각농도당 2일간오전과오후 2회검사하였고, 매검사마다 2회씩반복측정하여총 8회측정하였다. 이결과를바탕으로반복정밀도및검사실내비정밀도를구하였다. 4) 검체별비교평가검체종류별결과를비교하기위하여 36명의환자에서채혈한 lithium-heparin tube에서전혈검체를검사진행하고, 잔여검체를원심분리하여 (2,33 g, 7분 ) 얻은혈장을검사에사용하였다. 검체종류별로 2번측정하였다. 5) 참고범위설정건강검진을받은사람중심장또는신장과연관된질환을진단받은적이없고, 심전도정상, 혈청크레아티닌농도가 1.5 mg/dl 미만인 26세에서 75세사이의총 12명의정상인을대상으로 NTproBNP 값을 Samsung LABGEO PA CHF Test 로측정하여첨도와왜도를계산하여정규분포여부를확인하고, Z score 값을계산하여이상치를구분한후상위 97.5 백분위수값을참고범위로설정하였다. 6) 통계분석통계분석에는 SPSS version 22 (IBM Co., Armonk, NY, USA) 와 Microsoft Excel 21 (Microsoft Corporation, Redmond, WA, USA) 과 Analyse-it version 2.3 (Analyse-it Software, Ltd., Leeds, UK), MedCalc Statistical Software version 16.4.3 (MedCalc Software, Ostend, Belgium) 을이용하였다. 직선성평가에서선형회귀분석을통해회귀방정식과결정계수 (R 2 ) 를구하였으며, 다항회귀분석도시행하였다. 기기간, 검체간상관성평가에는 Passing-Bablok 회귀분석을통하여상관계수 (r) 를구하였고, Bland-Altman 도표로표현하였다. 136 www.labmedonline.org
결과 1. 정밀도 정밀도평가결과에서낮은농도 (153 pg/ml) 와높은농도 (1,5 pg/ml) 정도관리물질의검사중반복정밀도는각각 5.55%, 6.61% 였으며, 검사실내비정밀도는 6.68%, 6.73% 였다 (Table 1). 5. 참고범위설정총 12명의정상인의 NT-proBNP 결과값이비정규분포를형성하고있어서 Z score값을계산하였다. 모든결과값의 Z score 절대값이 3 미만이어서제거해야할이상치는없었다. 97.5 백분위수값은 58.3 pg/ml이었다. 따라서 NT-proBNP의참고범위를 58.3 pg/ ml 미만으로설정하였다. 2. 직선성직선성평가를위한회귀분석결과 1, pg/ml 범위에서결정계수 R 2 가.99이었으며 (Fig. 1), 측정치를가장잘반영하는방정식은 1차함수로좋은직선성을보였다. 고찰 본연구에서는심근표지자중 NT-proBNP 검사가의뢰된검체 를이용하여새롭게개발된 Samsung LABGEO PA CHF Test 검사 3. 상관성평가현재검사실에서사용하고있는 E17에대한 Samsung LABGEO PA CHF Test 의 NT-proBNP 상관성평가결과상관계수 (r) 는.93이며, 결과값차이의평균은 -3.9 % 이었다 (Fig. 2). 4. 검체별비교평가동일한환자의전혈과혈장검체를이용하여 NT-proBNP검사결과를비교분석한결과상관계수 (r) 은.99이며, Bland-Altman 분석결과두검체의결과값차이의평균은 5.9% 이었다 (Fig. 3). Samsung PA CHF Test (pg/ml) 6, 5, 4, 3, 2, 1, y=.564x-71.16 R 2 =.989 Table 1. Coefficients of variation (CVs) for NT-proBNP Imprecision (CV %) Low level (153 pg/ml) High level (1,5 pg/ml) Repeatability 5.55 6.61 Within-laboratory 6.68 6.73 Abbreviations: NT-proBNP, N-terminal pro-brain natriuretic peptide. 2, 4, 6, 8, 1, Expected concentration (pg/ml) Fig. 1. Linearity curves of measured values vs. expected values for NTproBNP. Abbreviation: NT-proBNP, amino-terminal pro-brain natriuretic peptide. NT-proBNP of Samsung PA CHF Test (pg/ml) 6, 5, 4, 3, 2, 1, (Samsung PA CHF Test - E17)/Average % 15 1 5-5 -1 +1.96 SD 76.4 Mean -3.9-1.96 SD -84.2 1, 2, 3, 4, 5, 6, 1, 2, 3, 4, 5, 6, NT-proBNP of E17 (pg/ml) A Mean of two methods B Fig. 2. Comparison between results from E17 and Samsung LABGEO PA CHF Test. (A) Passing and Bablok regression, y=6.5653+.9196x (r=.96), (B) Bland-Altman plots for the two methods. www.labmedonline.org 137
Whole blood (pg/ml) 6, 5, 4, 3, 2, 1, (Whole blood - plasma / Average % 3 25 2 15 1 5-5 -1-15 +1.96 SD 23. Mean 5.9-1.96 SD -11.2 1, 2, 3, 4, 5, 6, Plasma (pg/ml) A 1, 2, 3, 4, 5, 6, 7, Mean of whole blood and plasma B Fig. 3. Bland-Altman plots for whole blood and plasma specimens. (A) Passing and Bablok regression, y=-3.5451+1.77x (r=.99), (B) Bland-Altman plots for whole blood and plasma specimens. 의분석능및기존의검사방법 (E17) 과의비교분석을실시하였다. 검사실내비정밀도는 6.8% 미만으로 Ricos 등 [11] 이생물학적변이계수를이용하여계산하여제시한정밀도는 5.% 로약간높았다. 기존 POCT 장비의검사실내비정밀도의범위는대략 6. 1.7% 로검사실내비정밀도는기존의 POCT 장비와비슷하거나조금더나은것으로판단되었다 [7, 12, 13]. 여기서사용한검체가일치되지않았지만 Samsung LABGEO PA CHF Test 의검사실내비정밀도는충분히임상적으로유용성이있는범위로판단된다. 직선성평가에서구한회귀방정식 y =-71.16 +.564x 와상관성평가에서구한회귀방정식 y = 6.5653 +.9196x 과기울기와 y 절편의값이차이가상당하였다. 직선성평가에서는 2개잔여검체를이용하였지만상관성평가에서는 18개의잔여검체를이용하였으므로, 상관성평가에대해서구한회귀방정식이보다두방법간의관계를보다정확하게반영한다고생각을할수있다. 이렇게직선성평가에서상당한차이를보이는것에대한원인분석을위하여세분화된검체농도로추가적인평가를하지못한것이이연구의제한점중하나이다. 두방법의결과를비교하였을때평균적으로 E17의결과값보다 3.9% 정도낮게나왔다. 심부전의임상적 cut-off를문헌에따라연령에관계없는의학적의사결정농도 (medical decision level) 인 3 pg/ml [14] 에서구한회귀방정식을적용하면 Samsung LAB- GEO PA CHF Test 검사의값이 3 pg/ml일경우 E17의값은 319 pg/ml가나온다. Ricos 등 [11] 이생물학적변이계수를이용하여계산하여제시한총허용오차 (total allowable error) 는 13% 와바이어스 (bias) 4.7% 를적용하면 E17의값은 6.3% 가되기때문에제시하는 bias보다는크지만총허용오차보다는작다는것을확인할수있었다. 그리고, 검체종류별비교에서도계산한회귀방정식 을사용하면, 전혈검체의결과값이의학적의사결정농도인 3 pg/ml일때혈장검체의결과값은 282 pg/ml이며, 이값은 6.1% 가되기때문에 Ricos 등 [11] 이제시한바이어스보다는크지만총허용오차보다작다는것을확인할수있었다. 상관성평가에서 2번측정한값을사용하여서총허용오차보다는바이어스를적용하여평가하는것이보다정확하지만총허용오차의기준으로볼때에는크게다르지않다고평가를할수가있다. 본연구의제한점중의하나는앞에서제시한기준으로정상인의검체를구하기가쉽지않았기때문에 75세미만의연령대의그룹만으로구하였다는점이다. 참고범위는보고문헌과검사방법에따라차이가있지만대개, 정상 NT-proBNP 농도는 1-12 pg/ml 미만으로제시하고있다 [15, 16]. 본연구에서는성인의경우 58.3 pg/ml 로외국의다른참고범위에비해낮은값을보였다. 그리고 Wolber 등 [17] 이지적한것처럼정상성인중에심장질환이진행중인사람이포함될수있어정상치산정에주의를기울일필요가있다. 또한, 정상인각각혹은정상인간에도 NT-proBNP의생리적차이가비교적크게나타나참고범위설정을위해추가연구가필요하다 [18]. 울혈성심부전을진단하는데있어혈중 NT-proBNP가가장중요한지표로알려짐에따라이를정확히측정할수있는진단시약의필요성이증가하고있다. 또한, 다른심폐기계질환과의빠른감별을위해현장검사장비로혈중 NT-proBNP를측정하는것은그임상적유용성이클것으로예상된다 [19]. Samsung LABGEO PA CHF Test 를평가한정밀도, 직선성, 기존검사방법과의비교, 검체간비교, 참고치를고려하여볼때 Samsung LABGEO PA CHF Test 는유용하게사용될수있을것이다. 138 www.labmedonline.org
요약 배경 : 아미노말단풋뇌나트륨이뇨펩티드 (amino-terminal pro-brain natriuretic peptide, NT-proBNP) 는급성심부전의치료와예후평가에중요한생물표지자이다. 현장장비검사는 NT-proBNP를응급실등에서빠르게검출할수있다. 우리는새로운 NT-proBNP 검사장비인 Samsung LABGEO PA CHF Test 의분석능을평가하였다. 방법 : Clinical and Laboratory Standards Institute (CLSI) 가이드라인에따라정밀도, 직선성, 검사간비교가수행되었다. 전혈과혈장간의 NT-proBNP 값을구해검체종류별비교를시행하였다. 정해진기준에따라선별된건강한성인의잔여검체로참고범위를설정하였다. 결과 : Samsung LABGEO PA CHF Test 검사결과는약 18분이내에나왔다. 검사실내비정밀도는 6.8% 보다작았다. 1, pg/ ml 농도범위에서우수한직선성을보였으며결정계수는.99였다. E17 장비와의상관성은상관계수.96으로우수하였고전혈과혈장으로시행한검체종류별비교에서도상관계수.99로좋은상관성을보였다. 참고치설정은 26세에서 75세사이의건강인 12명의검체를분석하여 97.5 백분위에서 58.3 pg/ml로정했다. 결론 : 본연구에서, Samsung LABGEO PA CHF Test 는우수한분석능을보여주었다. Samsung LABGEO PA CHF Test 는현장장비검사로서특히응급실에서임상적으로유용하게사용될것으로보인다. 감사의글 본논문은분당서울대학교병원위탁연구비 (6-212-9) 지원에의해이루어진것임. REFERENCES 1. Lee JH, Lim NK, Cho MC, Park HY. Epidemiology of heart failure in Korea: present and future. Korean Circ J 216;46:658-64. 2. Baek KK, Jeon ES, Rhee IL, Kim SH, Kim JS, Song PS, et al. N-terminal pro-b-type natriuretic peptide as a prognostic marker in acute coronary syndrome. Korean Circ J 24;34:17-81. 3. Cantor WJ, Fitchett D, Borgundvaag B, Ducas J, Heffernan M, Cohen EA, et al. Routine early angioplasty after fibrinolysis for acute myocardial infarction. N Engl J Med 29;36:275-18. 4. Kim HN and Januzzi JL Jr. Natriuretic peptide testing in heart failure. Circulation 211;123:215-9. 5. Januzzi JL Jr, Camargo CA, Anwaruddin S, Baggish AL, Chen AA, Krauser DG, et al. The N-terminal Pro-BNP investigation of dyspnea in the emergency department (PRIDE) study. Am J Cardiol 25;95:948-54. 6. Bay M, Kirk V, Parner J, Hassager C, Nielsen H, Krogsgaard K, et al. NTproBNP: a new diagnostic screening tool to differentiate between patients with normal and reduced left ventricular systolic function. Heart 23;89:15-4. 7. Zaninotto M, Mion MM, Di Serio F, Caputo M, Ottomano C, Plebani M. PATHFAST NT-proBNP (N-terminal-pro B type natriuretic peptide): a multicenter evaluation of a new point-of-care assay. Clin Chem Lab Med 21;48:129-34. 8. Clinical and Laboratory Standards Institute. Evaluation of precision of quantitative measurement procedures; approved guideline. EP5-A3. Wayne, PA: Clinical and Laboratory Standards Institute, 214. 9. Clinical and Laboratory Standards Institute. Evaluation of the linearity of quantitative measurement procedures: a statistical approach; approved guideline. EP6-A. Wayne, PA: Clinical and Laboratory Standards Institute, 23. 1. Clinical and Laboratory Standards Institute. Measurement procedure comparison and bias estimation using patient samples; approved guideline - 2nd ed (interim revision). EP9-A3. Wayne, PA: Clinical and Laboratory Standards Institute, 213. 11. Ricos C, Alvarez V, Cava F, Garcia-Lario JV, Hernandez A, Jimenez CV, et al. Desirable specifications for total error, imprecision, and bias, derived from intra- and inter-individual biologic variation. Westgard QC. Retrieved from https://www.westgard.com/biodatabase1.htm, 214. 12. Khezri BS, Carlsson L, arsson A. Evaluation of the Alere NT-proBNP test for point of care testing. J Clin Lab Anal 216;3:29-2. 13. Gils C, Ramanathan R, Breindahl T, Brokner M, Christiansen AL, Eng O, et al. NT-proBNP on Cobas h 232 in point-of-care testing: Performance in the primary health care versus in the hospital laboratory. Scand J Clin Lab Invest 215;75:62-9. 14. Januzzi JL, van Kimmenade R, Lainchbury J, Bayes-Genis A, Ordonez- Llanos J, Santalo-Bel M, et al. NT-proBNP testing for diagnosis and shortterm prognosis in acute destabilized heart failure: an international pooled analysis of 1256 patients: the International Collaborative of NT-proBNP Study. Eur Heart J 26;27:33-7. 15. Shi X, Xu G, Xia T, Song Y, Lin Q. N-terminal-pro-B-type natriuretic peptide (NT-proBNP): reference range for Chinese apparently healthy people and clinical performance in Chinese elderly patients with heart failure. Clin Chim Acta 25;36:122-7. 16. Galasko GI, Lahiri A, Barnes SC, Collinson P, Senior R. What is the nor- www.labmedonline.org 139
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