Short-term increases of plasma cardiac troponin I are better evaluated by comparison with the reference change value

作者：Introcaso Giovanni^*; Raggi Monica; D'Errico Tiziana; Cavallero Annalisa

来源：Biochemia Medica, 2010, 20(3): 327-333.

• cardiac troponin-I
• reference change value
• analytical imprecision
• acute coronary syndrome

Introduction: We have investigated consecutive troponin I measurements using the Reference Change Value (RCV) at low concentrations, in patients admitted in Emergency Department (ED).
Materials and methods: Patients admitted for chest pain (N = 103) were evaluated retrospectively on the basis of two consecutive cardiac troponin-I (cTn-I) tests. The second test levels exceeding the "Critical Reference Change Value" (CrRCV), a quantity calculated on the basis of the first result and the RCV of cTn-I, were considered particularly relevant. Clinical cases were analysed matching the concentration change (significative or not) with acute coronary syndrome (clinically confirmed or not). Healthy individuals (N = 70) results and internal quality control results were evaluated for the calculation of, respectively, the biological and the analytical variation of plasma cTn-I.
Results: The cTn-I RCV was very high because of the high analytical variation of cTn-I in proximity of its decision limit, as shown by its imprecision profile study. Analysing data with the first result < 0.1 mu g/L we have obtained an cTn-I RCV negative predictive value - NPV = 88% (95% CI = 82-92%). The 4 groups of patients have demonstrated a clinically significant difference (Chi square test; P < 0.001).
Conclusions: The RCV allows to statistically evaluating the cTn-I increased levels in presence of the high imprecision of commercial cTn-I assay at low concentrations. This parameter could be applied in medical practice only for low cTn-I concentrations around the decision limit for the myocardial necrosis.

• 出版日期2010