The mean age of respondents (N=500) was 48.9 years (SD=14.4; range 18 to 83 years). Sixty percent were female, nearly two thirds (63.6%) were African American and one third (32.8%) were white; 19.4 percent reported less than a high school level of education attainment (). Patient literacy was limited; 20.1 percent were reading below a seventh grade level (low literacy) and 32.0 percent were reading at the seventh to eighth grade level (marginal literacy). Patients were taking an average of 2.9 prescription medications. Lower literacy was associated with older age (p<0.001), African American race (p<0.001), less education (p<0.001), and the Shreveport study site (p<0.001). No significant differences were reported between literacy level, gender or number of prescription medications taken daily.
Characteristics of Study Sample.
Overall, patients gave a total of 3,328 responses out of a possible 4,500 (74.0%) across the nine prescription drug warnings they were given to review; a non-response represented patients not attending to and attempting to interpret a warning on the bottle (). Overall rates of attendance to drug warnings on the prescription bottles significantly varied among standard, simplified text, and simplified text + icon warning labels (70.2%, 73.4%, and 78.3% respectively, p<0.001). Simplified text labels (with or without icons) that cautioned Use only on your skin, Talk to your doctor before using any over-the-counter drugs, and Do not stop taking unless directed by your doctor were more likely to be attended to by patients than their standard warning label counterparts (). Simplified text + icon labels stating to Take with food or milk and that a medication May cause drowsiness. Be careful when driving a car or using machinery were better attended by respondents than simplified text only or standard labels.
Attendance to and Correct Interpretation of Drug Warnings by Label Type.
Among the 3,328 patient attempts to interpret drug warnings, 403 (12.1%) were coded as incorrect (). Overall rates of correct interpretation significantly varied by label type; with simplified text + icon and simplified text only warnings more likely to be properly understood compared to standard warnings (92.1%, 90.6%, and 80.3% respectively; p<0.001). The same simplified text and simplified text + icon labels that were better attended to by patients compared to standard warnings were more likely to be correctly interpreted, with the inclusion of the instruction, Limit your time in the sun (). Simplified text labels that warned not to drink alcohol were better understood than standard warnings (98.3% vs. 89.3%, p=0.02).
In multivariate analyses, both label type and label order were associated with attendance to the auxiliary drug warning labels (). Simplified text labels, with and without patient-centered icons, were better attended to by patients than standard labels (simplified text - Adjusted Odds Ratio (AOR) 1.17, 95% Confidence Interval (CI) 1.02-1.36; simplified text + icon – AOR 1.59, 95% CI 1.38-1.83). When the reference group was altered from the standard label to the simplified text label, warnings that included both simplified text and icons were found to be better attended to than the labels with simplified text only (AOR 1.35, 95% CI 1.19-1.55; p<0.001). Labels that were not in the most prominent (first) position on the container were less likely to be attended to by patients (second position – AOR 0.79, 95% CI 0.70-0.90; third position – AOR 0.70, 95% CI 0.62-0.79). In addition, older age, male gender, and fewer years of schooling were statistically significant independent predictors of poorer attendance to drug warnings. A significant interaction was found between label type and literacy level. Patients with low literacy were more likely to attend to simplified text labels compared to the standard (AOR 1.60, 95% CI 1.09-2.33; p=0.02); no differences were noted between attendance to labels with simplified text vs. simplified text + icons by those with low literacy skills.
Generalized Estimating Equation (GEE) Model for Attendance to and Correct Interpretation of Prescription Drug Warning Labels.
Beyond attendance, prescription drug warning labels with simplified text and simplified text + icons were also significantly more likely to be correctly interpreted compared to standard labels (simplified text – AOR 2.64, 95% CI 2.00-3.48; simplified text + icons – AOR 3.26, 95% CI 2.46-4.32; ). When the reference group was changed to labels with simplified text only, patients’ ability to correctly interpret labels was not significantly different with the inclusion of the patient-centered icon (simplified text + icons – AOR 1.23, 95% CI 0.90-1.70, p=0.20). Low literacy was also a significant independent predictor of misinterpretation (AOR 0.65, 95% CI 0.44-0.94). Similar to the outcome of attendance, an interaction between label type and literacy level was found. Patients with marginal and low literacy were better able to correctly interpret warning labels with simplified text and icons compared to labels with simplified text only (marginal – AOR 2.59, 95% CI 1.24-5.44, p=0.01; low – AOR 3.22, 95% CI 1.39-7.50, p=0.006). Similar differences were found between simplified text and patient-centered icons and standard labels (which included both text and icons) among individuals with limited literacy (marginal – AOR 1.99, 95% CI 1.01-3.90, p=0.05; low – AOR 2.13, 95% CI 1.04-4.40, p=0.04).