So say researchers, including Louisiana State University's Terry Davis, Ph.D., and Northwestern University's Michael Wolf, Ph.D., M.P.H. They say nearly half the low-income patients they studied misinterpreted at least one instruction on five common prescription drug labels.
If patients misunderstand drug labels, they may take drugs incorrectly, which can be dangerous.
"It was surprising how prevalent mistakes were regardless of an individual's literacy level," Wolf says in a Northwestern University news release. "Just being able to read the label doesn't mean you'll be able to interpret it," he says. "Why are we not phrasing things properly on bottles?"
The study appears online in the Annals of Internal Medicine.
For their study, the researchers visited public health clinics in three cities: Shreveport, La., Jackson, Mich., and Chicago. At the clinics, they talked to 395 English-speaking, low-income patients. The patients ranged in age from 19 to 85, with just under 49 being the average. The scientists deliberately studied low-income patients because such patients are often disadvantaged in terms of health and health care.
Patients were shown labels for five common prescription drugs: two antibiotics, a cough medicine, a blood pressure drug, and a diuretic.
They read each label aloud, then answered questions about how they would take the drug. A panel of experts reviewed their answers.
Almost half the patients — 46 percent — were "unable to read and correctly state one or more of the label instructions," the researchers write. Those with poor reading skills were more likely to misunderstand the labels. But almost four out of 10 of those with "adequate" literacy skills made mistakes, according to the study.
Patients generally understood straightforward instructions, like "Take one tablet in the morning and one at 5 p.m." But some misread doses, such as mistaking "teaspoon" for "tablespoon." Others were thrown by complicated instructions.
For instance, 333 of the patients correctly read aloud the instruction, "Take two tablets by mouth twice daily." But when asked how many of those tablets they should take in a day, a third of them got the answer wrong. The right answer is four tablets per day.
"The most common misinterpretation was to take two pills a day," Wolf says in the news release.
"It's not that they couldn't figure out two plus two equals four," Wolf says. "Rather, it's the way the instructions were written. It's awkward wording."
The researchers call for more studies to research label formats that might be easier to understand.
SOURCES: Davis, T. Annals of Internal Medicine, Nov. 29, 2006; online edition. News release, Northwestern University.
By Miranda Hitti
Reviewed by Louise Chang, M.D