'Millions' prescribed wrong dose of common drugs

According to updated calculations published this week, over 11 million people in the United States may have been given the wrong prescription for a range of commonly used drugs.

Scientists from the Stanford University School of Medicine in California recently investigated the reliability of so-called pooled cohort equations (PCEs).

These dry-sounding sums perform a pivotal role in the prescribing of drugs, including blood pressure medications, statins, and aspirin.

PCEs help doctors to determine each patient's overall risk of stroke or heart attack.

Assessing cardiovascular risk helps to inform the physician about the exact level of medication that will be both effective and safe.

These equations are available as online web tools and smartphone apps, and they are even built into digital medical records.

Problems with PCEs

In recent years, some have called into question the accuracy of PCEs, asking whether the data that they rely on are outdated. If this were found to be the case, patients could potentially be at risk of taking dangerously high or ineffectively low doses of drugs.

Dr. Sanjay Basu, Ph.D., is an assistant professor of primary care outcomes research at Stanford. He set out to uncover whether PCEs should be improved. As he explains, "We found that there are probably at least two major ways to improve the 2013 equations."

His findings were published this week in the journal Annals of Internal Medicine.

The first issue that Dr. Basu identified was one that had been discussed for some time: "[T]he data used to derive the equations could be updated."

PCEs are based on various datasets, some of which are relatively old. For instance, one included information from people who were aged 30–62 in 1948.

Diet, lifestyle, health risks, and everything in-between have changed since those days. The study authors say that, because of the age of this information, people's risks were being estimated at around 20 percent higher than they truly were.

Dr. Basu notes dryly that "relying on our grandparents' data to make our treatment choices is probably not the best idea."

Other issues unearthed

Another issue the researchers identified was the lack of African-Americans in the datasets. It is now known that cardiovascular risk is significantly higher in the African-American population.

"So while many Americans were being recommended aggressive treatments that they may not have needed according to current guidelines, some Americans — particularly African-Americans — may have been given false reassurance and probably need to start treatment given our findings."

Dr. Sanjay Basu, Ph.D.

To rectify these shortcomings, the researchers added new data to improve the PCEs' accuracy. The data are currently maintained by the National Institutes of Health (NIH), and they have approved the new and updated equations.

Addressing the aged data was the first step, but there was a second issue to attend to. According to the researchers, some of the statistical methods behind the PCEs were also outdated. So, they brought them in line with current standards.

In the paper, the study authors explain, "We found that by revising the PCEs with new data and statistical methods, we could substantially improve the accuracy of cardiovascular disease risk estimates."

As the PCEs guide medical decisions involving some of the most commonly used prescription drugs — such as aspirins, blood pressure medications, and statins — these changes could potentially save and extend thousands of lives.