Contrary to historical evidence, two new studies show.
“By contrast with previous historical studies, our data show that LDL cholesterol is an important risk factor for myocardial infarction and atherosclerotic cardiovascular disease in a contemporary primary prevention cohort of individuals aged 70 to 100 years,” Borge Nordestgaard, MD, of the University of Copenhagen, and colleagues noted in the first of the two studies, published this week in the Lancet.
“By lowering LDL cholesterol in healthy individuals aged 70-100 years, the potential for preventing myocardial infarctions and atherosclerotic cardiovascular disease is huge, and at a substantially lower number needed to treat when compared with those aged 20-69 years,” they added.
“These findings support the concept of the cumulative burden of LDL cholesterol over one’s lifetime and the progressive increase in risk for atherosclerotic cardiovascular disease, including myocardial infarction, with age,” added Frederick J. Raal, PhD, and Farzahna Mohamed, MB BCh, of the University of the Witwatersrand, Johannesburg, South Africa, in an editorial published with both new studies in the Lancet (2020 Nov 10. doi: 10.1016/S0140-6736[20]32333-3).
The studies underscore the need for clinicians to consider continued risks associated with elevated LDL cholesterol in older age, they stressed, adding that statins are also beneficial for younger persons at risk to prevent conditions from worsening.
“The average age of patients in all the trials analyzed was older than 60 years, an age when atherosclerotic cardiovascular disease is already well established,” the editorialists wrote.
“Lipid-lowering therapy should be initiated at a younger age, preferably before age 40 years, in those at risk to delay the onset of atherosclerosis, rather than try to manage the condition once fully established or advanced,” they stressed.
No RCTs have included patients older than 70
For persons aged 40-75 years, elevated LDL cholesterol levels are a known risk factor for MI and atherosclerotic cardiovascular disease, and there is consensus in guidelines regarding treatment with statins.
However, the risk for people older than 70 is controversial. Some studies show little or no association between elevated LDL cholesterol levels and an increased risk for MI.
Contributing to the uncertainty is that few of the randomized, controlled trials that have investigated the question have included patients aged older than 70 years.
As a consequence, many practice guidelines have noted that the level of evidence in older patients is low, and some organizations have lowered the strength of recommendations regarding the treatment for older patients in comparison with younger patients.
Primary prevention: CV events increase with elevated LDL cholesterol in older age
Dr. Nordestgaard and colleagues studied data on 91,131 people living in Copenhagen who did not have atherosclerotic cardiovascular disease or diabetes at baseline and were not taking statins.
Of the participants, 10,592 were aged 70-79 years, and 3,188 participants were aged 80-100 years.
Over an average follow-up period of 7.7 years, 1,515 participants had a first MI, and 3,389 developed atherosclerotic cardiovascular disease.
In the primary-prevention cohort, after multivariate adjustment, the risk of having a heart attack per 1.0 mmol/L increase in LDL cholesterol was increased in the group overall (hazard ratio, 1.34). The increased risk was observed for all age groups, including those aged 80-100 years (HR, 1.28), 70-79 (HR, 1.25), 60-69 (HR, 1.29), 50-59 (HR, 1.28), and 20-49 (HR, 1.68).
Risk for atherosclerotic cardiovascular disease was also raised per 1.0 mmol/L increase in LDL cholesterol overall (HR, 1.16) and in all age groups, particularly those aged 70-100 years.
Greater elevations in LDL cholesterol (5.0 mmol/L or higher, indicative of possible familial hypercholesterolemia) were associated with a notably higher risk for heart attack after multivariate adjustment in people aged 80-100 (HR, 2.99). Risk was also higher among those aged 70-79 (HR, 1.82).
The highest incidence was in those older than 70. The rate was 8.5 heart attacks per 1,000 people per year among those aged 80-100 and 5.2 heart attacks per 1,000 in those aged 70-79. The rates were 2.5 per 1,000 among those 60-69, 1.8 for those aged 50-59, and 0.8 for those aged 20-49.
“The absolute risk [of cardiovascular events] is of course much higher in the elderly than those under the age of 75, but what was a surprise was how clear our results were on a relative risk scale, that the risk associated with elevated LDL [cholesterol] was as high in people aged 80-100 as the younger patients,” Dr. Nordestgaard said in an interview.
With regard to the benefits of cholesterol-lowering drugs, the study showed that the number needed to prevent one heart attack over 5 years was 80 among those aged 80-100; the number was 439 for people aged 50-59.
With regard to stronger statins, when moderate-intensity statins were used, the number needed to treat to prevent one cardiovascular disease event of any type dropped to 42 for patients aged 80-100. It was 88 for those aged 70-79, 164 for those aged 60-69, 345 for those aged 50-59, and 769 for those aged 20-49.
“The clinical significance of this is that it appears those in older age groups indeed benefit from cholesterol-lowering therapy,” Dr. Nordestgaard said. “I think many people have this idea that LDL [cholesterol] is not important over the age of about 70-75, but that’s not the case.”
“These robust findings are novel,” he and his colleagues stressed.
Despite these observational findings, the South African editorialists noted that “whether lipid-lowering therapy should be initiated for primary prevention in people aged 75 years or older is unclear,” owing to the host of risks and benefits that need to be balanced.
The findings of an ongoing randomized, placebo-controlled trial (STAREE) may answer this question, they wrote. It is investigating primary prevention in 18,000 older patients (≥70 years) who are being randomly assigned to receive atorvastatin 40 mg/d or placebo. The study is seeking to determine whether statin treatment extends the length of a disability-free life, which will be assessed on the basis of survival outside permanent residential care. Results are expected in 2022-2023.