Based on the study's findings, the authors estimate that every month, this cost-related medication skimping leads more than a million Americans with diabetes to use less medication for that illness than was prescribed to them, and causes more than 1.6 million people with asthma to miss some of their doses of medication.
The findings, from a nationally representative survey of 4,055 adults over the age of 50, are published in the October issue of the American Journal of Public Health by a team from the University of Michigan Health System, the Veterans Affairs Ann Arbor Healthcare System and Stanford University. The study was funded by the VA.
Not surprisingly, the study finds that seniors whose out-of-pocket prescription costs are more than $100 a month, and those with low incomes or no prescription drug coverage, are at the greatest risk for skimping on their medications.
Other results of the survey indicate that people with chronic illnesses were more likely to cut back on certain kinds of medications over others, suggesting that patients are selective about which drugs they go without.
"We found that many patients go without drugs that relieve serious symptomatic conditions such as back pain or ulcers, while others skipped drugs that are life-sustaining, such as blood pressure and cholesterol drugs, but that might not cause any noticeable difference in day-to-day functioning," says lead author John D. Piette, a VA Career Scientist and associate professor of internal medicine at the U-M Medical School.
More patients regularly cut back on costs by forgoing their medicines for depression, asthma, ulcers, arthritis, migraines and back pain, for example, than went without medicines for high blood pressure, high cholesterol or diabetes. Piette and his colleagues say their findings suggest that changes in prescription drug benefit policites will affect patients differently depending on their particular medical problems and possibly their demographic characteristics as well.
The data add to a growing list of findings on cost-related prescription drug skimping that have been published by the same group of researchers in the last few months.
In September, the group reported in the Archives of Internal Medicine that most chronically ill patients who cut back on prescription drugs due to cost don't tell their doctors they're doing so. And in June, they released the first long-term evidence that skimping on medications due to cost can lead to adverse health outcomes for chronically ill patients. In February, they reported that diabetes patients who forgo medication due to cost pressures have worse blood sugar control, symptoms and physical functioning.
"We're getting a clearer picture of how chronic illness, out-of-pocket cost, insurance and patient characteristics combine to create a pattern of non-adherence among older Americans," says Piette. "This is an issue that affects millions of Americans, and will influence their health for years to come."
No matter which drugs they cut back on, those patients who reported at least some cost-related adherence problems were describing a relatively frequent problem. In fact, 78 percent of those who reported ever having cut back on any medication due to cost in the last year also said they were forgoing treatment at least once a month.
Having insurance to cover drug costs didn't always mean patients were always able to stay on their medications, the researchers found. That's because cash co-payments and deductibles required by some insurance plans can add up to hundreds of dollars a month, especially for the large number of older adults with multiple chronic illnesses.
When the sample of surveyed adults was weighted to reflect national population characteristics, the researchers found that half of all respondents had monthly prescription-related costs of $50 or more, and 25 percent had monthly costs of $100 or more. Eighty-three percent of respondents had some form of prescription drug coverage, but even so, many of these patients reported that their monthly medication costs topped $100.
Those who didn't have insurance were the least likely to be able to afford out-of-pocket payments for drugs: Respondents who had incomes under $20,000 a year were more than twice as likely to be without drug coverage than those making more than $60,000 a year.
In general, there were no notable differences in cost-related medication under-use across groups defined by race, gender or educational attainment. However, the researchers found that patients over the age of 65 were substantially less likely to cut back on medications due to cost than those in their 50s. As a result, Piette says, planned Medicare reforms will not address the problems of medication cost pressures for those chronically ill patients who may need assistance the most: those under age 65.
In the study, the researchers examined risk factors for cost-related medication under-use separately for patients with the 10 most common chronic health problems. For example, people who had been prescribed drugs to control their blood pressure were more than four times as likely to skimp on their medicines if they paid more than $100 a month for all their medications than if they paid less than $100. Overall, about 7 percent of people with high blood pressure said they had cut back on their blood pressure medication due to cost at least once per month.
Similarly, people who had been prescribed drugs to treat depression were more than four times as likely to say they had cut back on a medication due to cost if they paid more than $100 a month for all their medications. And 14 percent of those patients who had prescriptions for antidepressants cut back on those depression medications each month due to cost.
In addition to Piette, the study's authors include Michele Heisler, M.D., M.P.A., also of the VA Ann Arbor Healthcare System and the U-M Medical School, and Todd H. Wagner, Ph.D., of the VA Health Economics Resource Center and Stanford University. Reference: AJPH: Oct. 2004, Vol. 94, No. 10, pp 1782-1787.