Misinterpreting data in lipidology in the era of COVID-19.

To the Editor,

We read with interest the report by Wei et al. recently accepted for publication in the Journal. After retrospectively evaluating cholesterol serum levels of 597 patients affected by coronavirus disease 2019 (COVID-19) and 50 age- and sex-matched healthy subjects, authors conclude that patients with COVID-19 develop hypolipidemia when symptoms are mild and that hypolipidemia worsens with disease severity. In an attempt to support their interpretation of the research, authors also report some statistically significant correlations among serum lipid levels and inflammatory parameters.

Authors state that “the hypolipidemia in COVID-19 patients shall raise an urgent awareness to physicians who are now in frontline fighting against this pandemic,” but their misinterpretation of the data runs the risk of misdirecting clinical practice.

First of all, although authors refer to “disease progression” throughout the article, their study is not suitable for evaluating the evolution of a clinical condition over time because it has a cross-over design (ie, patients were blood sampled only on admission).

Second, authors use “hypolipidemia” to refer to patients with total cholesterol <174 mg/dL. This definition of hypolipidemia is improper and substantially wrong in the absence of a genetic diagnosis. Furthermore, authors do not consider patients’ pharmacological treatment (eg, Were patients treated with lipid-lowering drugs? It is likely, judging by the prevalence of type 2 diabetes and cardiovascular disease in the study cohort!). Actually, the prevalence of subjects at high or very high cardiovascular risk—that was significantly higher in the “critical” group—could explain the observed findings on low-density lipoprotein cholesterol (LDL-C). Indeed, low levels of LDL-C in this group were likely due to a more intensive lipid-lowering treatment, as recommended by the latest international guidelines. , Finally, it is not even surprising that the course of disease was more severe for patients with these characteristics.

In conclusion, a deeper analysis of data and more investigations are needed before concluding for a connection between low LDL-C levels and COVID-19 infection severity.