Improving prescription drug warnings to promote patient comprehension.

Background: Prior studies have documented a high prevalence of patients who misunderstand prescription drug warning labels, placing them at risk for medication error. We evaluated whether the use of "enhanced print" drug warnings could improve patient comprehension beyond a current standard.
Methods: An evaluation of enhanced print warning labels was conducted at 2 academic and 2 community health primary care clinics in Chicago, Illinois, and Shreveport, Louisiana. In total, 500 adult patients were consecutively recruited and assigned to receive (1) current standard drug warning labels on prescription containers (standard), (2) drug warnings with text rewritten in plain language (simplified text), or (3) plain language and icons developed with patient feedback (simplified text + icon). The primary outcome was correct interpretation of 9 drug warning labels as determined by a blinded panel review of patients' verbatim responses.
Results: Overall rates of correct interpretation of drug warnings varied among standard, simplified text, and simplified text + icon labels (80.3%, 90.6%, and 92.1%, respectively; P < .001). Warnings with simplified text and simplified text + icons were more likely to be correctly interpreted compared with standard labels (simplified text - adjusted odds ratio [AOR] = 2.64; 95% confidence interval [CI], 2.00-3.49; simplified text + icons - AOR = 3.26; 95% CI, 2.46-4.32). Patients' ability to correctly interpret labels was not significantly different with the inclusion of icons (simplified text + icons - AOR = 1.23; 95% CI, 0.90-1.67; P = .20). Low literacy was also an independent predictor of misinterpretation (AOR, 0.65; 95% CI, 0.44-0.94). Patients with marginal and low literacy were better able to correctly interpret warning labels with simplified text + icons compared with labels with simplified text only (marginal literacy - AOR = 2.59; 95% CI, 1.24-5.44; P = .01; low literacy - AOR = 3.22; 95% CI, 1.39-7.50; P = .006).
Conclusions: Simple, explicit language on warning labels can increase patient understanding; the addition of appropriate icons is particularly useful for adults with lower literacy skills. Evidence-based standards are needed to promote patient-centered prescription labeling practices.