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 Editor,

Recognition of independent risk factors will allow for more accurate prognostication of morbidity and mortality in patients infected with SARS-CoV-2. We were interested to read the recent publication by Zhou et al. which attempted to identify risk factors for moderate, severe and critical Covid-19 infections. Additionally, they have proposed risk factors for cardiac injury in the context of Covid-19 [1].

Zhou et al. have suggested in Covid-19 patients with pre-existing diabetes mellitus and chronic kidney disease have increased risk of cardiac injury. However, previous research has established patients with chronic kidney disease and diabetes mellitus present with higher baseline troponin assays [2,3]. Consequently, the diagnosis of cardiac injury in these patients becomes more challenging with a single troponin level. Further work would benefit from the inclusion of dynamic troponin levels. Similarly, they neglect to comment on the distribution of gender amongst individual risk factors. Given that research has shown peak troponin I to be 4-fold higher in men, gender can act as a confounder when relying on a single troponin-I level as a diagnostic criterion [4]. In addition they are deriving these conclusions on cardiac risk profile based on relatively small numbers with less than 10% of patients having a positive troponin result.

We would encourage the authors to provide more data on cardiac injury in patients infected with Covid-19 and look forward to reviewing future data with larger groups of patient. Further work should address the above issues before accurate risk stratification tools can be developed.

Declaration of Competing Interest

None.