Iowa City, IA—Despite concerns that taking PCSK9 inhibitors to achieve very low levels of cholesterol could led to adverse events such as memory impairment or nervous system disorders, that does not seem to be the case according to a recent study.

The report, published in the Journal of the American College of Cardiology, identified an increased risk of cataracts, however.

Researchers from the Preventive Intervention Center at the University of Iowa and colleagues note that PCSK9 inhibitors can reduce cholesterol by large amounts in high-risk patients, but questions have been raised as to how very low levels of LDL cholesterol might affect body functions.

In an effort to answer those concerns, researchers pooled data from 14 randomized, controlled studies that included 5,234 patients treated with the PCSK9 drug alirocumab for up to 2 years. The focus was any occurrence of adverse events in patients who achieved two or more consecutive LDL cholesterol values of less than 25 mg/dL—the level needed for normal cell function—or less than 15 mg/dL.

Results indicate that, overall, incidence of adverse events was similar in patients taking alirocumab compared to those taking placebo, including musculoskeletal events, neurologic conditions, neurocognitive events (including memory), renal events, or liver events. No increased incidence of diabetes was detected, despite previous studies showing an excess of diabetes in patients with LDL cholesterol <30 mg/dL on statin therapy.

On the other hand, an increased incidence of cataracts in patients with LDL <25 versus >25 was uncovered. In a propensity score analysis, the rate of cataracts was 2.6% in the group with lower cholesterol as opposed to 0.8% in those with higher levels, for a hazard ratio of 3.40, according to the report. No difference in cataract incidence was observed between pooled alirocumab and control groups.

Study authors suggest that the result could be an indicator that reducing cholesterol accelerates underlying aging-related changes, contributing to cataracts, or it could simply be an anomaly.

“The safety of these new drugs is critical to patients who have no other means by which to control their life-threatening high cholesterol,” explained lead author Jennifer Robinson, MD, MPH. “The long-term effects of very low levels of LDL cholesterol are under evaluation in ongoing large clinical trials.”

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