Reply to Letter to the Editor - in response to: Cardiac injury prediction and lymphocyte immunity and inflammation analysis in hospitalized patients with coronavirus disease 2019 (COVID-19).

Dear Dr. Tan and colleagues,

Thanks for your letter [1] with the interests in our work [2]. We agree for higher blood troponin baseline in renal dysfunction patients; however, increased level of troponin baseline depends on degree of renal dysfunction. Usually, most situations of exceeding 99th percentile URL only happen in patients with severely renal dysfunction [3]. In our study [2], the median creatinine in the nineteen patients with cardiac injury was 91 (66–108) μmol/L; therefore, the diagnostic specificity for cardiac injury with blood troponin is not affected greatly by this potential confounder. In addition, diabetes was potentially associated with increased hs-cTnT baseline [4], rather than hs-cTnI level we used [2]. Definitely the suggested using dynamic troponin levels will be better than single test.

We also agree for the gender-specific hs-cTnI cutoffs. However, their clinical applications remain not extensive because it may increase identification of female cases but decrease identification of males with cardiac injury [5]. In addition, the patient median age was 67 years old, postmenopaused ages [2]. Therefore, we remained using a single 99th percentile URL as criterion and there were no statistically significant differences in gender between two groups [2].

We realized a limitation of our study with the relatively small number of patients. Among the total 68 patients, the percentage of positive hs-cTn I results was 28% [2] (Results 3.3), instead of less 10% [1]. We hope more data about cardiac injury in COVID-19 patients available to assist us for assessing the risk of cardiac damage.

Declaration of Competing Interest

None.