Analysis of Variation for Parallel Test between Reagent Lots in in-vitro Laboratory of Nuclear Medicine Department

핵의학 체외검사실에서 시약 lot간 parallel test 시 변이 분석

Purpose In in-vitro laboratories of nuclear medicine department, when the reagent lot or reagent lot changes Comparability test or parallel test is performed to determine whether the results between lots are reliable. The most commonly used standard domestic laboratories is to obtain %difference from the difference in results between two lots of reagents, and then many laboratories are set the standard to less than 20% at low concentrations and less than 10% at medium and high concentrations. If the range is deviated from the standard, the test is considered failed and it is repeated until the result falls within the standard range. In this study, several tests are selected that are performed in nuclear medicine in-vitro laboratories to analyze parallel test results and to establish criteria for customized percent difference for each test. Materials and Methods From January to November 2018, the result of parallel test for reagent lot change is analyzed for 7 items including thyroid-stimulating hormone (TSH), free thyroxine (FT4), carcinoembryonic antigen (CEA), CA-125, prostate-specific antigen (PSA), HBs-Ab and Insulin. The RIA-MAT 280 system which adopted the principle of IRMA is used for TSH, FT4, CEA, CA-125 and PSA. TECAN automated dispensing equipment and GAMMA-10 is used to measure insulin test. For the test of HBs-Ab, HAMILTON automated dispensing equipment and Cobra Gamma ray measuring instrument are used. Separate reagent, customized calibrator and quality control materials are used in this experiment. Results 1. TSH [%diffrence Max / Mean / Median] (P-value by t-test > 0.05) C-1(low concentration) [14.8 / 4.4 / 3.7 / 0.0 ] C-2(middle concentration) [10.1 / 4.2 / 3.7 / 0.0] 2. FT4 [%diffrence Max / Mean / Median] (P-value by t-test > 0.05) C-1(low concentration) [10.0 / 4.2 / 3.9 / 0.0] C-2(high concentration) [9.6 / 3.3 / 3.1 / 0.0 ] 3. CA-125 [%diffrence Max / Mean / Median] (P-value by t-test > 0.05) C-1(middle concentration) [9.6 / 4.3 / 4.3 / 0.3] C-2(high concentration) [6.5 / 3.5 / 4.3 / 0.4] 4. CEA [%diffrence Max / Mean / median] (P-value by t-test > 0.05) C-1(low concentration) [9.8 / 4.2 / 3.0 / 0.0] C-2(middle concentration) [8.7 / 3.7 / 2.3 / 0.3] 5. PSA [%diffrence Max / Mean / Median] (P-value by t-test > 0.05) C-1(low concentration) [15.4 / 7.6 / 8.2 / 0.0] C-2(middle concentration) [8.8 / 4.5 / 4.8 / 0.9] 6. HBs-Ab [%diffrence Max / Mean / Median] (P-value by t-test > 0.05) C-1(middle concentration) [9.6 / 3.7 / 2.7 / 0.2] C-2(high concentration) [8.9 / 4.1 / 3.6 / 0.3] 7. Insulin [%diffrence Max / Mean / Median] (P-value by t-test > 0.05) C-1(middle concentration) [8.7 / 3.1 / 2.4 / 0.9] C-2(high concentration) [8.3 / 3.2 / 1.5 / 0.1] In some low concentration measurements, the percent difference is found above 10 to nearly 15 percent in result of target value calculated at a lower concentration. In addition, when the value is measured after Standard level 6, which is the highest value of reagents in the dispensing sequence, the result would have been affected by a hook effect. Overall, there was no significant difference in lot change of quality control material (p-value>0.05). Conclusion Variations between reagent lots are not large in immunoradiometric assays. It is likely that this is due to the selection of items that have relatively high detection rate in the immunoradiometric method and several remeasurements. In most test results, the difference was less than 10 percent, which was within the standard range. TSH control level 1 and PSA control level 1, which have low concentration target value, exceeded 10 percent more than twice, but it did not result in a value that was near 20 percent. As a result, it is required to perform a longer period of observation for more homogenized average results and to obtain laboratory-specific acceptance criteria for each item. Also, it is advised to study observations considering various variables.

핵의학 체외 검사실 에서는 시약 Lot가 변경될 때, Lot 간의 결과가 신뢰성이 있는지를 판단하기 위해 Lot 간 동등성 검사(comparability test between reagent lots) 또는 시약 병행 검사(reagent parallel test)를 시행하는데, 다수의 국내 검사실에서는 두 lot 간 결과 차이로부터 %difference를 구하여 저농도에서는 20% 이내, 중 고농도에서는 10% 이내로 설정하고 있으며 범위를 벗어 날 경우 재검사 시행으로 범위를 맞추는 실정이다. 따라서 본원의 핵의학 체외 검사실에서 시행되는 몇 가지 검사를 선정하여 parallel test의 결과를 분석해보았고, 검사별 맞춤 %difference 값 선정에 도움 될 만한 참고 자료를 마련해 보고자 하였다. Thyroid-stimulating hormone(TSH), Free thyroxine(FT4), Carcinoembryonic antigen(CEA), CA-125, Prostate-specific antigen(PSA) 그리고 HBs-Ab, insulin, 7종목에 대해 2018 1월부터 2018년 11월까지의 기간 동안의 시약 lot 변화에 따른 정도 관리 물질의 결과를 분석하였다. TSH, F-T4, CEA, CA-125, PSA의 측정에는 IRMA의 원리를 이용한 RIA-MAT 280 system이 사용되었고, Insulin의 측정에는 TECAN 자동화 분주 장비와 GAMMA-10 측정 장비가 사용되었다. HBs-Ab의 측정에는 HAMILTON 자동화 분주 장비와 GAMMA-10 측정 장비가 사용되었다. 각각 전용 시약과 전용 칼리브레이터, 전용 정도 관리 물질이 사용되었다. 1. TSH [%diffrence Max / Mean / Median] (P-value by t-test > 0.05) C-1(저농도) [14.8 / 4.4 / 3.7 / 0.0 ] C-2(중농도) [10.1 / 4.2 / 3.7 / 0.0] 2. FT4 [%diffrence Max / Mean / Median] (P-value by t-test > 0.05) C-1(저농도) [10.0 / 4.2 / 3.9 / 0.0] C-2(고농도) [9.6 / 3.3 / 3.1 / 0.0 ] 3. CA-125 [%diffrence Max / Mean / median] (P-value by t-test > 0.05) C-1(중농도) [9.6 / 4.3 / 4.3 / 0.3] C-2(고농도) [6.5 / 3.5 / 4.3 / 0.4] 4. CEA [%diffrence Max / Mean / median] (P-value by t-test > 0.05) C-1(저농도) [9.8 / 4.2 / 3.0 / 0.0] C-2(중농도) [8.7 / 3.7 / 2.3 / 0.3] 5. PSA [%diffrence Max / Mean / Median] (P-value by t-test > 0.05) C-1(저농도) [15.4 / 7.6 / 8.2 / 0.0] C-2(중농도) [8.8 / 4.5 / 4.8 / 0.9] 6. HBs-Ab [%diffrence Max / Mean / Median] (P-value by t-test > 0.05) C-1(중농도) [9.6 / 3.7 / 2.7 / 0.2] C-2(고농도) [8.9 / 4.1 / 3.6 / 0.3] 7. insulin [%diffrence Max / Mean / Median] (P-value by t-test > 0.05) C-1(중농도) [8.7 / 3.1 / 2.4 / 0.9] C-2(고농도) [8.3 / 3.2 / 1.5 / 0.1] 모두 정도 관리 물질의 lot 변경 시에도 유의미한 차이가 없었으며 표본 수가 늘어남에 따라 검사실과 검사 종목 별 맞춤 허용 기준을 설정할 수 있을 것이라 기대할 수 있었다. 면역 방사 계수 측정법에서 비교적 검출률이 높은 종목들을 선정해서 일 것이라 판단되며 여러 번 재 측정된 결과 값이기 때문일 수도 있겠다. 대부분의 검사 결과에서 허용 기준인 10%에 크게 못 미치는 차이를 보였으며 저농도 target 값을 가진 경우에도 허용 기준인 20%에 가까운 수치를 보이진 않았다. 더 오랜 기간 동안의 관찰과 연구를 통해 평균의 균질화가 이루어진다면 종목 별 검사실 맞춤 허용 기준을 얻을 수 있을 것으로 판단되며 더 다양한 변수를 고려한 관찰과 연구도 필요할 것이다.