New data strengthen the evidence linking high-potency statins to acute kidney injury (AKI) in a small fraction of patients with kidney disease, whether chronic or not, although the danger is low for most individuals.

Patients with non-chronic kidney disease had a 34% greater chance of being hospitalized for AKI if they started taking high-potency statins in the previous 120 days than if they began using low-potency statins in that period. Patients with chronic kidney disease (CKD) had a 10% increased risk, the researchers reported online ahead of print in the British Medical Journal (BMJ 2013;346:f880).

The investigators calculated that 1,700 patients with non-chronic kidney disease would need to be treated with a high-potency rather than a low-potency statin for 120 days to result one additional hospitalization for AKI.

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“The absolute risk increase in AKI with high vs. low dose statin is small, and the associated number needed to harm—that is the number of patients who would need to receive a high vs. low dose to realize one additional AKI event—is large,” said co-investigator Amit Garg, MD, PhD, Director of the London Kidney Clinical Research Unit and a professor in the departments of medicine and epidemiology at the University of Western Ontario in London. The study’s use of an administrative database, however, likely underestimates the true AKI incidence, and also “many millions of patients worldwide receive a statin each year,” Dr. Garg said. “So it remains prudent to be cognizant of this risk.”

Lead investigator Colin Dormuth, ScD, MSc, chair of the University of British Columbia’s PharmacoEpidemiology Working Group, added that statin use must be individualized.

“Expected benefits of treatment should be placed in context of suspected harms, including AKI and diabetes,” Dr. Dormuth said. “To this end, one would want to consider the benefit/harm profile in younger healthier patients, or harm in the frail elderly who probably should not be on a statin anyway.”

The team focused on the records of 2,067,639 patients who were participating in Canadian, American and U.K. health care databases and were newly exposed to statins between January 1, 1997 and April 30, 2008. They defined high-potency statin treatment as at least 10 mg rosuvastatin/day, at least 20 mg atorvastatin/day, and at least 40 mg/day of simvastatin.

A total of 59,636 patients had CKD and used statins within the three-year period before they entered the database; 2,008,003 had non-chronic kidney disease and used statins within three years of entering the database. The patients were equally split between the two sexes and had an average age of 68 years.

The rates of hospitalization for AKI in patients with non-chronic kidney disease and who were under 65 years ranged from 1.0-3.5/1,000. The corresponding range in those 65 and over was 3.1-4.0/1,000. Furthermore, the rates were much higher in those with CKD, ranging from 10-63/1,000.

An as-treated analysis of hospitalization for AKI up to two years after cohort entry in patients non-chronic kidney disease revealed a 34% higher rate with high-potency than with low-potency statins. The study found no statistically significant difference in rates in the non-chronic kidney disease population.

The researchers pointed out in their paper that there likely is “a small magnitude of incremental cardiovascular benefit of high-potency statins over low-potency statins,” and therefore the key is learning “to identify patients for whom the risk-benefit balance for high-potency statin treatment is unfavorable.”

In an accompanying editorial, Robert Fassett, MD, and Jeff Coombes, MD, of the University of Queensland in Brisbane, Australia, conclude that “clinicians should use low-potency statins whenever possible to provide cardiovascular benefits without the increased risk of acute kidney injury.”