Statins, which are used to lower the cholesterol levels in the body, may be associated with a slightly reduced risk of death from COVID-19, according to a large study conducted in Sweden.

Statins are a recommended and common intervention for preventing cardiovascular events by reducing levels of lipoprotein cholesterol in the blood. During the pandemic, it has been debated whether statins influence the risk of death from COVID-19. The researchers at Karolinska Institutet in Sweden conducted the largest population study to date in the field. The study, recently published in the journal PLOS Medicine, indicates that statin treatment slightly lowers COVID-19 mortality. Earlier studies did not provide a clear answer and often suffered from the limitation that they only included hospital inpatients.

Using data from Swedish registers, the researchers of the latest study followed 963,876 residents of Stockholm over the age of 45 between March and November 2020. The findings are based on analyses of data on the participants' prescribed medication and healthcare and from the Cause of Death Register.

The information was analysed with respect to such factors as diagnosed medical conditions. The study shows that statin treatment was associated with a slightly lower risk of dying from COVID-19, a correlation that did not vary significantly among risk groups. "Our results suggest that statin treatment can have a moderate prophylactic effect on COVID-19 mortality," said study co-first author Rita Bergqvist, a medical student at Karolinska Institutet. The researchers noted that randomised studies will be needed to ascertain whether there is a causal relationship.

"All in all, our findings support the continued use of statins for conditions such as cardiovascular disease and high levels of blood lipids in line with current recommendations during the COVID-19 pandemic," said study co-first author Viktor Ahlqvist, a doctoral student at Karolinska Institutet.

The researchers noted one limitation of the study which concerns the use of prescription data without the possibility of checking individual drug use. They were also not able to control for risk factors such as smoking and high body mass index (BMI), only diagnosed health status.