Understanding of drug indications by ambulatory care patients

Patients' knowledge of the indications of their prescription medications was studied and those medications that were most likely to be taken without patients understanding the correct indication were identified.

Adult patients who received care at four primary care practices were surveyed. Patients were eligible to participate if they were over 18 years old and had received a prescription from a participating physician at a clinic visit. Patients were telephoned and asked to retrieve the bottles of all medications they were currently taking, identify their medications, and state the reason they took each medicine. The primary outcome was absent or incorrect knowledge of a drug's indication.

A total of 2340 prescription medications were used by the 616 patients whose data were analyzed. Eighty-three patients (13.5%) lacked knowledge of the indication for at least one of their prescription medications. They did not know the indication for 148 medications (6.3%). After multivariable adjustment, lack of knowledge was more common for cardiovascular drugs (odds ratio [OR], 1.50; 95% confidence interval [CI], 1.03-2.19) and less common for diabetes medications (OR, 0.37; 95% CI, 0.16-0.84) and analgesics (OR, 0.23; 95% CI, 0.05-1.01) compared with all other medications, and more common if the patient taking these medications was older, black, or had a high school education or less.

More than 13% of patients in primary care practices did not know the indication of at least one of their prescription medications. Lack of knowledge was most prevalent for cardiovascular medications.