CKMB在心肌梗死患者的诊断限选择

Selection of Diagnostic Cutoff Value of CKMB in the Patients with Suspicious Myocardial Infarction

目的比较不同CKMB诊断限对心肌梗死(MI)诊断所造成的影响。方法测定927例心肌梗塞可疑病例入院24小时内,血中cTnI和CKMB水平。分别以两倍参考范围上限值、健康人群第99百分位数、健康人群第97.5百分位数、正常参考范围上限、ROC曲线确定的最佳截断点作为Cutoff值,比较CKMB的阳性率、诊断效率、与cTnI的符合程度。结果应用不同诊断限时,CKMB阳性率从2.7%到8.3%;cTnI(+)/CKMB(+)例数从18例(1.9%)到30例(3.2%);cTnI(-)/CKMB(-)例数从842例(90.8%)到802例(86.5%)。cTnI(+)/CKMB(+)病例中的cTnI的浓度要明显高于cTnI(+)/CKMB(-)病例中的浓度。结论采用较低的诊断限(ROC)时,CKMB阳性率增加,和cTnI的符合程度较好,有较高的诊断效率。

Objective To compare different diagnostic outcome of suspicious myocardial infarction （MI） when applying different cutoff value of Creatine Kinase MB （CKMB）. Materials We measured plasma levels of cardiac troponin （cTNI） and CKMB of 927 consecutive patients with suspected MI in 24h after admission. The positive rate, diagnostic efficiency as well as the coincidence rate of cTNI and CKMB were compared based on different CKMB cutoff value, including twice the ULR （ 〉 50U/L）, 99^th percentile, 97.5th percentile, ULR and optimum cutoff value determined by ROC curve （ 〉 21U/L）. Results The positive rate of CKMB ranged from 2.7% when using twice URL as cutoff value to 8.3% when using the ROC recommended cutoff value; the positive coincidence rate of cTNI and CKMB ranged from 1.9% （18） to 3.2% （30）; the negative coincidence rate of cTNI and CKMB ranged from 90.8% （842） to 86.5% （802）. The level of plasma cTNI in cTNI （ ＋ ） /CKMB （ ＋ ） cases was obviously higher than that in cTNI （ ＋ ） /CKMB （-） cases. Conclusions Applying lower diagnostic cutoff value of CKMB as recommended by ROC curve can notably increase the rates of CKMB （ ＋ ） cases, the concordance with cTNI and diagnostic efficiency.