Concern about harm from antihyperglycemic and antihypertensive medications is associated with their underuse among patients with diabetes, even after controlling for economic factors.
The finding, from a survey of 803 adults with diabetes in Flint, Mich., suggests that “Because medication concerns may directly influence cost-related underuse, improved illness outcome may be achievable by simultaneously addressing attitudinal and economic issues,” wrote Dr. James E. Aikens and Dr. John D. Piette (Diabetes Care 2009;32:19–24).
The survey included 803 diabetes patients using antihyperglycemic agents, of whom 573 also used antihypertensive medications. Slightly more than half of the total group was black, and slightly more than half was female. More than a third had low functional health literacy (FHL) as measured by validated scales. The patients had a mean hemoglobin A1c (HbA1c) of 7.8% and mean blood pressure of 139/83 mm Hg.
Patients' treatment beliefs were measured with the well-validated Beliefs About Medicines Questionnaire (BMQ), with separate versions for the two types of medications. Five items are designed to elicit perceived medication necessity—such as “My health, at present, depends on my [diabetes or blood pressure] medication.” Six items pertain to concern, such as “I sometimes worry about the long-term effects of my … medicine.” For each item, patients choose from a 5-point response scale, ranging from “strongly agree” to “strongly disagree.”
Overall, perceived necessity was stronger than concern for both types of medication. Patients taking both types rated the antihyperglycemics as being both more necessary and more concerning than the antihypertensive medication, although the effect sizes were relatively small, said Dr. Aikens and Dr. Piette of the University of Michigan, Ann Arbor.
Perceived necessity for one or both types of medication was stronger among participants who were younger, female, had more comorbid conditions, were prescribed more medications, and were prescribed insulin. Perceived harmfulness of one or both types of medications was stronger among those who were younger, were black, were of low income, were diagnosed with more comorbid conditions, were dissatisfied with medication information, and were of low FHL.
“Given that perceived discrimination and distrust in health care have been documented in African Americans with diabetes, the most culturally sensitive interventions will be those that deal directly and skillfully with medication fears,” they said.
After adjustment for age, sex, ethnicity, and income, perceived need for antihyperglycemic medications was independently associated with having a greater number of prescriptions and being prescribed insulin. In contrast, concern about antihyperglycemic medications was associated with dissatisfaction with medication information, low FHL, and high out-of-pocket prescription costs.
Perceived need for antihypertensives—after adjustment for age, sex, ethnicity, and income—was associated with more comorbid conditions and satisfaction with medication information. As with antihyperglycemics, concern about antihypertensives also was associated with dissatisfaction with medication information and low FHL.
Medication underuse was measured by two questions: “In the past 12 months, have you ever taken less of your [diabetes/hypertension] medication than prescribed by your doctor because of the cost?” and “Many people do not take their prescription medication exactly as prescribed by their doctor. In the past year, have you ever taken less of your … medication for any reason other than the cost?”
Almost half (47%) of participants reported antihyperglycemic underuse, of whom about a third (16.5% of the total) reported cost-related underuse. However, concern about the medications was associated with both cost-related and non-cost-related underuse. Neither perception of medical necessity nor concern regarding antihyperglycemics was significantly related to HbA1c, although the relationship with concern nearly reached significance.
Of those prescribed antihypertensives, 31% reported underuse, with cost being a reason for about half (15%) of the group.
The study was funded by the American Diabetes Association and the Michigan Diabetes Research and Training Center, with a grant from the National Institutes of Health. The investigators reported no potential conflicts of interest.