One-third of prescriptions unfilled
TORONTO—A new Canadian study suggests nearly one-in-three new prescriptions goes unfilled, with expensive drugs and medications used to control some chronic conditions more likely not to be taken as directed.
The lead author of the work admitted the magnitude of the gap between prescriptions written and drugs purchased was greater than she and her co-authors expected—even though the figure was in line with a previous American study looking at the issue.
“In fact, we kept on lengthening the window that we looked at to make sure that was the case, actually.”
The study was published Monday in the journal Annals of Internal Medicine. It was funded by the Canadian Institutes of Health Research (CIHR).
The findings are based on data from Quebec.
Everyone in that province has drug coverage, either through their employment or through a provincial program that covers people like seniors, students, welfare recipients, people who are self-employed, and employees of small businesses who wouldn’t otherwise have drug plans.
The authors analyzed data on nearly 16,000 patients who were prescribed 37,506 new prescriptions from the beginning of 2006 to the end of 2009.
Of those, 31.3 percent were not filled nine months after the prescription was written.
Researchers who were not involved in the paper called the findings important, though one pointed out they may not be completely generalizable to the entire Canadian population.
Steve Morgan, director of the University of British Columbia’s Centre for Health Services and Policy Research, suggested the people studied represent a “somewhat vulnerable” population—meaning they might have lower incomes and less capacity to cover co-payments if they are required by the drug plan.
Tamblyn acknowledged the findings might have been somewhat different if the study also encompassed people with workplace drug plans.
Those people might be more affluent, and in some cases their drug plans might be more generous.
But Tamblyn said some findings likely would remain the same, noting other research has shown that prescriptions for expensive drugs are less likely to be filled than more moderately-priced ones.
The study looked at prescription records only. The authors did not talk to the patients about why they did or didn’t fill a prescription, so they cannot say what is behind the behaviour.
Tamblyn said she and her colleagues plan to do a follow-up study to mine that issue with patients.
But there are clues in the types of prescriptions that are filled and those which go unfilled.
For instance, the percentage of unfilled prescriptions for treatment of urinary tract infections—which are painful and difficult to ignore—was comparatively low (21 percent).
Likewise, antibiotics, which are used (and abused) to tackle infections, are generally filled.
But prescriptions for episodic conditions—things that come and go, such as migraine headaches or rashes—had comparatively high rates of non-adherence, meaning they more often were left unfilled.
Prescriptions for higher-priced drugs were more likely to go unfilled. And patients who had higher drug co-payments were more likely not to fill prescriptions.
Prescriptions for antidepressants, which many experts believe are over-prescribed, were not filled 38 percent of the time.
But drugs for coronary artery disease, high blood pressure, high cholesterol, and diabetes also were among those for which prescriptions were less likely to be filled—which, in many cases, probably isn’t the right approach.
“Some drugs, when appropriately prescribed, will keep people out of the hospital,” Morgan noted.
Tamblyn said the finding related to drugs for chronic conditions may be due to the fact that these types of medications are generally not short-term.