Improving patient understanding of prescription drug label instructions.

BACKGROUND: Patient misunderstanding of instructions on prescription drug labels is common and a likely cause of medication error and less effective treatment. OBJECTIVE: To test whether the use of more explicit language to describe dose and frequency of use for prescribed drugs could improve comprehension, especially among patients with limited literacy. DESIGN: Cross-sectional study using in-person, structured interviews. PATIENTS: Three hundred and fifty-nine adults waiting for an appointment in two hospital-based primary care clinics and one federally qualified health center in Shreveport, Louisiana; Chicago, Illinois; and New York, New York, respectively. MEASUREMENT: Correct understanding of each of ten label instructions as determined by a blinded panel review of patients' verbatim responses. RESULTS: Patient understanding of prescription label instructions ranged from 53% for the least understood to 89% for the most commonly understood label. Patients were significantly more likely to understand instructions with explicit times periods (i.e., morning) or precise times of day compared to instructions stating times per day (i.e., twice) or hourly intervals (89%, 77%, 61%, and 53%, respectively, p < 0.001). In multivariate analyses, dosage instructions with specific times or time periods were significantly more likely to be understood compared to instructions stating times per day (time periods--adjusted relative risk ratio (ARR) 0.42, 95% Confidence Interval (CI) 0.34-0.52; specific times--ARR 0.60, 95% CI 0.49-0.74). Low and marginal literacy remained statistically significant independent predictors of misinterpreting instructions (low--ARR 2.70, 95% CI 1.81-4.03; marginal--ARR 1.66, 95% CI 1.18-2.32). CONCLUSIONS: Use of precise wording on prescription drug label instructions can improve patient comprehension. However, patients with limited literacy were more likely to misinterpret instructions despite use of more explicit language.

Low literacy impairs comprehension of prescription drug warning labels.

BACKGROUND: Adverse events resulting from medication error are a serious concern. Patients' literacy and their ability to understand medication information are increasingly seen as a safety issue. OBJECTIVE: To examine whether adult patients receiving primary care services at a public hospital clinic were able to correctly interpret commonly used prescription medication warning labels. DESIGN: In-person structured interviews with literacy assessment. SETTING: Public hospital, primary care clinic. PARTICIPANTS: A total of 251 adult patients waiting for an appointment at the Louisiana State University Health Sciences Center in Shreveport (LSUHSC-S) Primary Care Clinic. MEASUREMENTS: Correct interpretation, as determined by expert panel review of patients' verbatim responses, for each of 8 commonly used prescription medication warning labels. RESULTS: Approximately one-third of patients (n=74) were reading at or below the 6th-grade level (low literacy). Patient comprehension of warning labels was associated with one's literacy level. Multistep instructions proved difficult for patients across all literacy levels. After controlling for relevant potential confounding variables, patients with low literacy were 3.4 times less likely to interpret prescription medication warning labels correctly (95% confidence interval: 2.3 to 4.9). CONCLUSIONS: Patients with low literacy had difficulty understanding prescription medication warning labels. Patients of all literacy levels had better understanding of warning labels that contained single-step versus multiple-step instructions. Warning labels should be developed with consumer participation, especially with lower literate populations, to ensure comprehension of short, concise messages created with familiar words and recognizable icons.