Age- and Sex-Specific Criteria Could Sharpen Statin Treatment Guidelines: Analysis

Pam Harrison

March 27, 2015

SAN DIEGO, CA — Establishing age- and sex-specific 10-year risk thresholds to identify adults to be considered for statins might improve the treatment's number-needed-to-treat balance and enhance the overall performance of the treatment guidelines, new research suggests[1].

"What we wanted to know was not just how many people were affected by the new guidelines but whether or not the guidelines performed differently in men vs women and in younger vs older individuals," Dr Ann Marie Navar-Boggan (Duke University Medical Center, Durham, NC) told heartwire from Medscape. "We found that the ability of current cholesterol guidelines to identify adults who will develop cardiovascular disease in the next 10 years varies significantly across age- and sex-specific groups."

Navar-Boggan is lead author on the study, published March 2, 2015 in the Journal of the American College of Cardiology; it was also presented here at the American College of Cardiology (ACC) 2015 Scientific Sessions.

The study population included 3685 adults, average age 57.2 years, from the Framingham Offspring Study, with no CVD at baseline. Researchers calculated patients' 10-year estimated CV event risk based on the pooled cohort equations and followed the cohort for events over 10 years, stratifying results by age. The events included nonfatal MI, coronary heart disease death, fatal or nonfatal stroke, peripheral arterial disease, and heart failure.

"Overall, 46.8% of adults met criteria for statin therapy based on the current guidelines' 10-year risk threshold of 7.5%," investigators report.

But those numbers varied considerably by age and sex. For example, using a threshold of 7.5%, the sensitivity of the guidelines was relatively poor in women and men between 40 and 55 years of age, identifying only 36% of women and 48% of men who would go on to have CVD over the next 10 years.

"When we moved the threshold to 5%, the sensitivity improved markedly in men, increasing from 48% to 71%, and in women, from 36% to 48%," according to Navar-Boggan. "From this, we conclude that in younger men and women, the 5% threshold that is currently optional in the guidelines should be encouraged."

The greatest differences between men and women in terms of how many the current guidelines would identify for statin therapy occurred in middle-aged men and women between 56 and 65 years of age. In this age group, 84% of men were recommended for statin therapy based on the current guidelines but only 29% of women.

"In the older age group, we saw what a lot of people have been concerned about already," Navar-Boggan observed. Because age is such a big driver of CVD risk and such an important part of the equations used to predict this risk, 97% of men and 85% of women between 66 and 75 years of age would be recommended for statin therapy at a risk threshold of 7.5%.

"Even if we raised the threshold to 15%, 89% of the men still meet statin recommendations under the current guidelines."

On the other hand, of adults between 66 and 75 years of age who do not go on to have CVD over the next 10 years, only 3% are currently identified as not needing statin therapy.

"We're hardly missing anyone who is going to develop CVD, but what we're doing is treating a significant number who aren't going to have a problem in the next 10 years," Dr. Navar-Boggan said.

"In young people, use of the guideline's 7.5% threshold will miss many adults who will go on to have heart disease, so it's reasonable to talk about statin therapy in younger adults at a 5% risk threshold, taking into consideration other CVD risk factors," she said.

"And it may also be reasonable for physicians to think about using a 15% or even a 20% threshold in older men as well as a 10% to 15% threshold in older women to help avoid unnecessary treatment."

Dr Anthony Wierzbicki (King's College London, UK) chair of the National Institute for Health and Care Excellence (NICE) that provides guidance to UK National Health Services, told heartwire that the problem with current risk-calculation systems is that the great majority of the risk can be principally attributed to age and to a lesser extent gender.

"That's why there has been a trend for some guidelines to move toward lifetime-based risk calculations and to promote a greater focus on modifiable risk factors," he said.

There's the additional problem of not yet having a good way of identifying people in their 60s and 70s who have atherosclerotic disease who will subsequently develop a CV event and those who have some disease that won't affect them for the rest of their lives, according to Wierzbicki.

Scientists in the UK recommend physicians use the QRISK2 risk assessment tool to assess CVD risk, which, as reported by heartwire , helps separate out those who are genuinely at risk for a CV event vs those who are not, at least in a UK population.

"If you just go by age and gender [for risk assessment] then you'll end up minimizing the effect of all the modifiable risk factors, so you won't end up picking up the smokers, the hypertensives, or the hypercholesterolemics; that's the down side of it," Wierzbicki said.

"The upside is you'll get 100% population coverage, which is better than the calculation systems in use now, where they can only pick up about 70% of the population at risk."

The study was supported by unrestricted grants from the Doggone Foundation along with research funds from the Duke Clinical Research Institute. Navar-Boggan disclosed no relevant financial relationships; disclosures for the coauthors are listed in the article.

 

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