Objective
We sought to evaluate the effectiveness of a pharmaceutical labeling strategy intended to improve comprehension of a teratogen warning.
Study design
This is a secondary analysis that evaluated women of childbearing age who were assigned prescription containers with the current teratogen warning, a label with simplified text, or a label with simplified text and icons. The association between label type and understanding of label instructions was assessed.
Results
A total of 132 women were interviewed. Comprehension of the icon label (94%) was higher than for the standard and enhanced text-only labels (76% and 79%), respectively ( P < .05). Adjustment for age, race/ethnicity, education, literacy, and number of current medications revealed that the label with the enhanced text and icon yielded superior comprehension (risk ratio vs standard, 1.26; 95% confidence interval, 1.04–1.53; risk ratio vs enhanced, 1.22; 95% confidence interval, 1.02–1.46).
Conclusion
In our study, a teratogen warning label that had easy-to-read messages with icons significantly improved comprehension.
The use of medications during the preconceptional period of pregnancy is a frequent occurrence. Andrade et al reported that 64% of pregnant women are prescribed a drug (other than a vitamin or mineral) during their pregnancy and nearly 5% of women may be taking a class X medication at the time of conception. Similarly, a large retrospective study by Schwarz et al found that 1 in 6 women of reproductive age filled a prescription for a class D or X medication over the course of a year. These classes of medications are of particular importance as they have the potential to cause harm to the developing fetus and should either be avoided completely or used only when the benefits of the treatment outweigh the risks. Specific examples include valproic acid, phenytoin, and warfarin.
See related editorial, page 281
For Editors’ Commentary, see Table of Contents
Because the use of teratogenic medications among reproductive-age women increases the risk of congenital anomalies, it is important that women taking these medications understand the risks such therapy may incur. One method toward understanding these risks is through physician counseling. Yet, because approximately 50% of pregnancies in the United States are not planned, a preconceptional consultation often does not occur. Moreover, many women never receive contraceptive counseling when their medication is prescribed. In the study by Schwarz et al, up to half of patients taking class D or X medications did not have documented contraceptive counseling or were not actively using contraception. Consequently, warnings conveyed on medication labels are often the only way many women are informed of the potential danger of a medication in the context of pregnancy. This fact emphasizes the importance these labels have in conveying the potential reproductive consequences of medication use.
Despite the importance of clear labeling, prior studies have suggested that warning symbols are often misinterpreted by individuals, especially those with limited literacy. Recognizing this tendency toward misinterpretation, the Food and Drug Administration along with numerous medical, pharmaceutical, and public health organizations have directed greater attention to the quality of prescription drug labeling. To date, though, little progress has been made by these organizations in improving or standardizing warning labels for prescription drug containers.
We recently developed and pilot tested an “enhanced” prescription drug warning label strategy that we hypothesized would be more easily understood by a diverse set of individuals, including those with limited literacy. The objective of the current study was to evaluate the effectiveness of the enhanced labeling strategy to improve comprehension of a pregnancy warning label among women of childbearing age.
Materials and methods
This is a secondary analysis of a 3-arm clinical trial testing the efficacy of different approaches to pharmaceutical labeling. In the main study, multiple types of warning labels were tested in a population of men and women of varying ages. The present secondary analysis concerns only those labels that were designed to be precautionary for a pregnant and/or breast-feeding population and only the subjects (ie, reproductive-age females) for whom those labels are primarily intended.
The specific protocol used in the original study has been described previously. Briefly, a convenience sample of adult patients who attended 1 of 4 outpatient primary care clinics was recruited in 2 cities (Shreveport, LA, and Chicago, IL) from June through August 2007. Patients were considered eligible for the study if they were English speaking and ≥18 years of age, and ineligible if they had severely impaired vision or hearing. Institutional review boards at both locations approved the study. A total of 562 patients were approached in the order they arrived at the clinics and prior to the medical encounter. Of the 500 (89%) patients who were eligible and consented to the larger study, 132 were women of childbearing age (18-44 years of age) and included in the present analysis.
In each of the participating clinics patients reviewed: (1) the current standard drug warning label for prescription containers (standard); (2) an “enhanced” drug warning with text rewritten in plain language (enhanced text); or (3) the enhanced language and an icon developed with patient feedback to support the text message (enhanced text + icon). The label they reviewed was varied based on a systematic rotation. The text and icons ( Figure ) on the labels were designed based on patient feedback and pilot testing. Additionally, guidelines established by the International Organization for Standardization for the development and testing of universal icons were followed. Other design elements were also implemented, including removal of color and optimizing of font size.
A structured “cognitive” interview protocol was developed to assess patient understanding of the drug labels, as previously described by our research team. In summary, after patients consented to the study, a trained research assistant obtained demographic information (age, sex, race/ethnicity, education, number of prescription medications currently taken daily) and administered the structured interview. Actual prescription pill bottle containers with the attached drug warning labels were then shown to all of the patients for review. During this interview, the research assistant would direct patients to the back of 1 of 3 prescription vials, and ask: “In your own words, what does this mean to you?” The patient’s verbatim responses were documented on a separate form. Once the patient provided their interpretations, the research assistant administered the Rapid Estimate of Adult Literacy in Medicine (REALM), a reading recognition test comprised of 66 health-related words. Based on REALM scores, participants were classified as having limited (≤6th-grade reading level; REALM = 0-44), marginal (7th- to 8th-grade reading level; REALM = 45-60), or adequate (≥9th-grade reading level; REALM = 61-66) health literacy skills. The REALM is the most commonly used test of patient literacy in medical settings. It is highly correlated with standardized reading tests and the Test of Functional Health Literacy in Adults.
Responses regarding the prescription label were then independently rated as either correct or incorrect by 3 attending physicians from 3 different academic medical centers. Each physician rater was blinded to all patient information and was trained to follow stringent coding guidelines agreed upon previously by the research team. Specifically, correct scores were to be given only if the patient’s response included all aspects of the label’s message. Responses were given an incorrect score if they were inaccurate, or if they did not contain all aspects of the warning. If a consensus decision was not obtained the final score was assigned through majority rule. Cohen kappa was calculated to assess interrater agreement.
Frequencies were calculated and Fisher’s exact tests were used to evaluate the association among label type (current standard vs enhanced text vs enhanced text + icon), literacy level (low, marginal, adequate), and patient understanding of the label instructions (correct, incorrect). A generalized linear model with a Poisson distribution and log link function was used to estimate the risk ratio (RR) and corresponding 95% confidence intervals (CIs) of correct interpretation of warning label instructions for covariates in the model compared to each referent condition. Robust error estimation was used to correct for overestimation of variance resulting from using the Poisson distribution for a binomial outcome. In addition to the primary independent variable of interest (label type), the final multivariable model included the potential confounding variables of age, sex, race (African American vs white), low literacy, education, and number of daily medications currently taken. While educational attainment is associated with literacy, it was included in the final model to present conservative estimates of the effect of literacy on rates of understanding. Study site was also entered into the model to adjust for any potential differences across study locations. All statistical analyses were performed using software (STATA, version 10.1; StataCorp, College Station, TX).
Results
The demographic characteristics of the study sample (n = 132) are presented in Table 1 . Briefly, the women who were evaluated were mostly African American, and many had relatively low educational attainment (59.9% high school level of education or less) and limited literacy skills. These women were taking on average 2.1 prescription medications daily (SD = 2.5). As noted, there were no differences in characteristics of the women with relation to the type of label that they visualized.
| Variable | n | Summary value | Label type | P value | ||
|---|---|---|---|---|---|---|
| Standard (n = 50) | Enhanced (n = 49) | Enhanced + icon (n = 33) | ||||
| Age, y | 132 | 31.9 (7.7) | 31.6 (7.3) | 31.9 (8.3) | 32.2 (7.6) | .94 |
| Race | .47 | |||||
| African American | 102 | 77.3 | 80.0 | 77.5 | 72.7 | |
| White | 25 | 18.9 | 14.0 | 18.4 | 27.3 | |
| Other | 5 | 3.8 | 6.0 | 4.1 | 0.0 | |
| Education, y | .60 | |||||
| <12 | 36 | 27.3 | 24.0 | 30.6 | 27.3 | |
| 12 | 43 | 32.6 | 38.0 | 22.5 | 39.4 | |
| 13-15 | 34 | 25.8 | 24.0 | 32.6 | 18.2 | |
| 16-20 | 19 | 14.4 | 14.0 | 14.3 | 15.1 | |
| Health literacy | .64 | |||||
| Low | 24 | 18.2 | 20.0 | 14.3 | 21.2 | |
| Marginal | 52 | 39.4 | 44.0 | 40.8 | 30.3 | |
| Adequate | 56 | 42.4 | 36.0 | 44.9 | 48.5 | |
| Medications taken daily | 132 | 2.1 (2.5) | 1.8 (2.1) | 2.3 (2.9) | 2.3 (2.6) | .45 |
| Study location | .88 | |||||
| Chicago, IL | 95 | 71.9 | 74.0 | 69.4 | 72.7 | |
| Shreveport, LA | 37 | 28.0 | 26.0 | 30.6 | 27.3 | |
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