A recent study conducted by a team of international scientists has highlighted that individuals with high serum levels of high-density lipoprotein-cholesterol are less susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The study is currently available on Preprints with The Lancet*.
Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 is associated with a wide variety of clinical consequences, ranging from mild respiratory infection to severe pneumonia, multiorgan failure, and death. Older adults and those with comorbidities, including pulmonary disease, diabetes, and cardiovascular disease, are at higher risk of developing severe COVID-19.
It is well-established in the literature that low-density and high-density lipoproteins play vital roles in triggering cardiovascular complications and ameliorating inflammation, respectively. Since COVID-19 is associated with both inflammation and cardiovascular complications, many studies have been conducted to evaluate the relationship between serum cholesterol levels and COVID-19 outcomes. In this context, the evidence suggests that low serum levels of low-density lipoprotein (LDL), high-density lipoprotein (HDL), and total cholesterol at hospital admission are associated with poor COVID-19 prognosis and death.
In the current study, the scientists have investigated whether serum lipid levels over the period of two years prior to COVID-19 testing can influence the risk and outcomes of COVID-19. They have also assessed serum levels of lipids before COVID-19 diagnosis, at the time of diagnosis, and two months after diagnosis.
The study was conducted on 11001 adults who underwent COVID-19 testing. The serum levels of HDL, LDL, total cholesterol, or triglyceride were tested at least twice during the two years period prior to COVID-19 testing.
Based on the trajectories of serum lipid levels, the participants were categorized into low-, medium-, and high-lipid groups using a group-based trajectory modeling. In addition, a similar categorization of the participants was done based on the tertiles of the 6-month average of lipid levels.
The primary outcome of the study was a SARS-CoV-2-positive test result. In addition, the study assessed the requirement of COVID-19 related hospitalization, in-hospital development of severe disease, and death.
About 12% of the study participants (1340 out of 11001) tested positive for COVID-19. Among these patients, 27% were admitted to the hospital, and the average duration of hospital stay was six days. About 23% of patients had a severe infection at the time of admission, and 5% of patients developed severe COVID-19 during their hospital stay. About 16% of hospitalized patients died during their hospital stay.
Serum lipid levels and risk of COVID-19
The statistical analysis conducted to determine the association between serum lipid levels and risk of COVID-19 revealed that higher HDL levels over the period of two years before COVID-19 testing is associated with a lower risk of acquiring SARS-CoV-2 infection. However, no significant association was observed between the levels of LDL, total cholesterol, and triglyceride and the risk of COVID-19.
The analysis of serum lipid levels before, at the time of, and after testing in COVID-positive and non-COVID participants revealed significantly lower levels of HDL, LDL, and total cholesterol among COVID-19 patients at the time of testing. The levels returned to the normal range six months after testing positive.
Serum lipid levels and COVID-19 outcome
The comparison between serum lipid levels and COVID-19 outcomes revealed that the serum lipid levels over the period of two years before COVID-19 testing are not associated with the development of severe disease or COVID-related mortality. Similarly, in COVID-19 patients, no significant association was observed between the pre-testing lipid levels and markers of inflammation except for HDL, which showed a positive correlation with C-reactive protein (CRP) level during the disease course.
The study findings indicate that individuals with high serum HDL levels for a period of two years are at a lower risk of developing COVID-19. The association between low HDL levels and low CRP levels highlights the impact of HDL in reducing infection-induced inflammation.
As suggested by the scientists, therapeutic interventions aiming at increasing serum HDL levels could be beneficial for preventing SARS-CoV-2 infection and severe COVID-19.
Preprints with The Lancet publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.