TORONTO -- Cholesterol medication has been linked to reduced risk of death from COVID-19, according to a new, large-population study.

Statins are often prescribed by doctors to help lower cholesterol levels in the blood and can help prevent cardiovascular events such as heart attacks and stroke.

"Our results suggest that statin treatment can have a moderate prophylactic effect on COVID-19 mortality," Rita Bergqvist, medical student at the Karolinska Institutet in Sweden and co-author of the study, said in a news release.

Previous studies attempting to ascertain a relationship between use of the drugs and COVID-19 deaths did not provide concrete answers. This led researchers to carry out the largest population study to date on the relationship between statins and COVID-19 mortality.

The study, published Thursday in the journal PLOS Medicine, analyzed the medical data of all 963,876 residents in the Stockholm area aged 45 and up from March 1, 2020, to Nov. 11, 2020. Among them, 169,642 were prescribed statins between March 1, 2019 and Feb. 29, 2020.

Those who were prescribed statins were older on average (71 years old versus 58 years old), more often diagnosed with comorbidities (23.3 per cent versus 1.6 per cent) and more frequently on anticoagulant and antihypertensive treatments, among other factors.

A total of 2,545 residents from the entire cohort died from COVID-19 during the analysis period, including 765 of those prescribed statins (0.45 per cent of group) and 1,780 who weren't (0.2 per cent of group).

After adjustments were made with respect to relevant medical data, such as pre-existing medical conditions, results showed that statin treatment was actually associated with a slightly lower risk of dying from COVID-19. The correlation also didn't vary significantly between risk groups.

"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 Viktor Ahlqvist, co-author and doctoral student at the university's global public health department.

It should be noted, the authors say, that randomized studies will need to be conducted to determine if there is a causal relationship.

One limitation of the study was that it used prescription data while not being able to account for actual drug use. The researchers were also not able to control for risk factors, such as smoking and high BMI, only diagnosed health status.