Data mining: Biological and temporal factors associated with blood cardiac troponin I concentration in a Chinese population

Background: Cardiac troponin is the cornerstone biomarker for the diagnosis of acute myocardial infarction. The aims of this study were to evaluate the association of biological and temporal factors with plasma cardiac troponin 1 (cTnI) concentration in a large group of Chinese outpatients and to explore which factor (sex, age, time of blood sampling, and season of the year) had the largest influence on plasma cTnI levels. Methods: Analytical data with outpatient cTnI results were downloaded from the laboratory information system from January 1, 2012 to September 20, 2018. All cTnI measurements were performed with a Siemens Dimension EXL automatic chemiluminescence immunoassay analyzer. A statistical method was used to strictly exclude outliers. A total of 86,381 outpatients were enrolled in the study. Results: In individuals over 60 years old, cTnI levels gradually increased with age in both males and females. cTnl reached its highest levels in individuals over 80 years old (0.030 mu g/L in males and 0.027 mu g/L in females). In individuals over 70 years old, cTnI levels were significantly higher in males than in females (P < .05). cTnI concentration varied between individuals with different times of blood sampling. In both men and women, cTnl concentrations reached a maximum at 05:00 (0.030 mu g/L and 0.026 mu g/L, respectively) and peaked again at 20:00 (0.029 mu g/L and 0.023 mu g/L, respectively). Additionally, there were significant differences in cTnI levels between the four seasons of the year (P < .05). In winter, cTnl levels were usually higher than in spring. Linear regression analysis showed that the factor "age >= 80" had the greatest impact on cTnI levels. Conclusion: Plasma cTnI levels were significantly influenced by sex, age, time of blood sampling, and season of the year. Thus, in order to avoid incorrect identification of cTnl values as abnormal, a cTnI reference interval should be established, taking into consideration the sex and age of the individual, the time of day of blood sampling, and the season of the year.