Health literacy is the degree to which individuals have the capacity to obtain, process, and understand basic health information needed to make appropriate health decisions.1 In 2003, the U.S. government conducted the National Assessment of Adult Literacy, which showed that more than 89 million American adults have limited health literacy skills and that these individuals come from all parts of society.2,3 Patients with limited health literacy are found in all clinical practices and cannot reliably be identified by physician estimation.2 The number of patients with limited health literacy is increasing and is more common among those with low educational attainment, immigrants, older persons, and racial–ethnic minorities.2,4 These patients have less knowledge of their health problems, more hospitalizations, higher health care costs, and poorer health status than those with adequate health literacy.5–9
Screening mammography contributes significant reduction to breast cancer mortality.10,11 Pertinent to the research reported here, there is mixed evidence on the relationship between health literacy and mammogram screening. Prior studies have found that more than one third of women with limited health literacy do not know the purpose of mammograms and that limited health literacy is associated with never having had a mammogram.12,13 Other research, however, found no association between health literacy and mammography screening.14
Given that several studies demonstrate compliance with routine screening mammography at or below 50%,15–17 and given the aforementioned studies that yielded differing findings, our study investigates the relationship of health literacy and screening mammography.
MATERIALS AND METHODS
This study was conducted at Maricopa Medical Center in Phoenix, Arizona, and approved by the medical center's institutional review board. Maricopa Medical Center is the safety net hospital for Maricopa County, which includes the city of Phoenix and the surrounding metropolitan area. Maricopa County is the state's most populous area, with nearly 4 million of Arizona's 6.5 million inhabitants. Maricopa Medical Center serves a patient population of which 78% of patients are from racial–ethnic minority groups and 79% are underinsured, uninsured, or insured by Medicaid.
Beginning on January 14, 2010, and continuing until April 1, 2013, every patient at least 40 years of age seen in the breast clinic was considered for inclusion in this study, which included a health literacy assessment as part of their routine history and physical examination. Male patients and patients diagnosed with breast cancer before age 40 years and seen during the study period for follow-up were excluded.
Health literacy assessment involves the use of validated instruments. The most widely used instruments are the Test of Functional Health Literacy in Adults, the Rapid Estimate of Adult Literacy in Medicine, and the Newest Vital Sign. The Test of Functional Health Literacy in Adults is commonly used in research,18 but it requires 18–22 minutes to administer and thus is not suitable for use in routine practice settings. The Rapid Estimate of Adult Literacy in Medicine can be administered in only 2–3 minutes, but it is only available in English, which makes it suboptimal for practices with large multilingual populations.19 The Newest Vital Sign can also be administered in approximately 2 minutes. It has the advantage of having been validated in both English and Spanish.20–23 The Newest Vital Sign was chosen because of the high percentage of Spanish-speaking patients in our patient population and its minimal time requirement.23
The Newest Vital Sign uses a nutrition label, similar to the nutrition label present on all packaged food in the United States. The nutritional label was tested as one of many scenarios developed by a panel of health literacy experts based on concepts and types of scenarios used in health literacy research and in general literacy assessments. The candidate scenarios tested involved both reading and numeracy skills because this was driven by research indicating that these skills are highly correlated with one another plus an intuitive understanding that patients must be able to use and understand both text and numbers if they are to successfully deal with today's health care system. Of the candidate scenarios tested, the nutritional label performed the best and has been validated and correlates well with more complicated health literacy instruments.20
The assessment involves asking the patient five questions (and a sixth qualifier question, if needed) about the nutrition label (Fig. 1). One point is awarded for each correct answer. Instructions accompanying the nutrition label specify what the interviewer should ask and they list the only acceptable answer(s). Scoring instructions for the Newest Vital Sign categorize patients into three groups, depending on how many of the six questions are answered correctly. A score of 0–1 indicates a high likelihood of limited health literacy. A score of 2–3 indicates the possibility of limited health literacy. A score of 4–6 indicates adequate health literacy. The instrument validation, including its sensitivity and specificity among Spanish speakers, has been previously described.20
The details of routine health literacy assessment as part of the standard history and physical examination have been described previously.23 In short, the assessment was performed by the clinician during the history and physical examination. However, if the patient was Spanish-speaking, the assessment was performed by a hospital-certified Spanish translator or a clinician who was a native Spanish speaker. No special personnel or other resources were used for performance of the health literacy assessment. Patients were excluded from health literacy assessment if they did not speak English or Spanish, could not see the health literacy assessment tool well enough, or had cognitive limitations as a result of developmental delay, dementia, psychiatric illness, or head injury.
The records of patients seen during the study period were reviewed to determine if they had undergone screening mammography. For all patients who were already being followed by the breast clinic for breast cancer or based on risk status, their records were reviewed to determine if they had undergone screening mammography at the time of their first visit. The majority of the current study population was new consultations being seen for a clinical breast complaint or abnormal mammogram and was either referred by their primary care provider or self-referred. As a result, nearly all patients had a recent mammogram before their visit.
Therefore, to determine patients' use of screening mammography, patients 50 years and older were considered to have undergone screening if they had another mammogram approximately 1 year before (within 15 months of) their most recent mammogram. For patients 40–49 years of age, an interval of 2 years from the most recent mammogram was used. These intervals were chosen because they had been the long-standing screening mammography guidelines before the changes made by the U.S. Preventive Services Task Force.24 Screening mammography for women 40 years and older are still supported by the American College of Obstetricians and Gynecologists, American Cancer Society, National Comprehensive Cancer Network, and American College of Radiology. For patients who were 40–42 years of age, however, because this is the normal time for the first mammogram, they were considered to have undergone screening mammography if they had a mammogram and were not being evaluated for a clinical breast complaint (ie, breast pain, mass, discharge). Starting on May 1, 2011, patients who reported not having undergone screening mammography were asked, in an open-ended fashion, if there was a reason for not doing so.
For all patients, sociodemographic information was collected and included age, education, body mass index (calculated as weight (kg)/[height (m)]2), self-reported monthly income, race–ethnicity, employment status, insurance status, family history of breast cancer in a first-degree relative, and current smoking status, use of alcohol, and drug use. Race and ethnicity was determined by the patient's self-identification.
Age, education, body mass index, number of live births, and estimated monthly income were analyzed as continuous variables. Race–ethnicity (non-Hispanic white compared with other, Hispanic compared with non-Hispanic), employment status (employed compared with not), and insurance status (uninsured compared with insured) were analyzed as categorical variables. A two-sample t test was used to determine if there were significant differences in continuous sociodemographic variables between women who did and did not undergo mammograms. A Fisher's exact test was used to compare the categorical variables to see if there were differences between women who did and did not undergo mammograms. All statistical tests were two-sided and significance levels were set at .05.
The association between health literacy and use of screening mammography was assessed. Adequacy of health literacy was analyzed as a categorical variable. Patients with scores of 4–6 were categorized as having “adequate health literacy.” Patients with scores of 0–1 and 2–3 had similar use of mammography and were therefore combined the two groups into a single group labeled “low health literacy.” Analysis of the data did not demonstrate differences when the patients were categorized into three groups or in the two groups as presented.
A logistic regression analysis was then performed with the dependent variable being whether or not a patient had undergone screening mammography. The Newest Vital Sign score (adequate compared with low literacy) was the key independent variable along with the sociodemographic variables that had been shown in unadjusted analysis to differ between women who did and did not obtain mammograms. Both unadjusted and adjusted odds ratios (ORs) derived from logistic regression models were calculated as well as the associated 95% confidence intervals (CIs) and P values. Based on the results of the logistic regression model, analysis was performed to determine which variable had the greatest effect on use of screening mammography. Of the covariates, health literacy had a smallest P value and OR. We also compared c (concordance) statistic (a measure for goodness of fit) between various models. The model without health literacy had the smallest c statistic. This indicates health literacy had the strongest association after adjusting for other covariates (including age).
A total of 1,664 patients aged 40 years of age or older were seen at least once at the breast clinic from January 14, 2010, to April 1, 2013. The population was racially and ethnically diverse (Table 1). Only 49% spoke English. Ninety percent of patients were enrolled in the Arizona Health Care Cost Containment System (the Arizona Medicaid plan) or were uninsured. More than 54% of patients were unemployed. The mean income of the population was $1,028 per month. Study participants had completed an average of 10 years of education (Table 1).
Of the 1,664 patients, only 71 (4.3%) patients could not undergo the Newest Vital Sign. Reasons included not speaking English or Spanish (n=35), inability to see well enough to view the study instrument (n=19), and any one or more of the following conditions (n=26): deafness, Down syndrome, Alzheimer disease, dementia, psychiatric illness, head injury with cognitive impairment, or a combination of these.
Of the remaining 1,594 patients, 1,593 (99.9%) underwent health literacy assessment as part of the routine history and physical examination during their clinic visit. Only one patient was inadvertently missed and no patients declined to complete the assessment. Health literacy assessment with the Newest Vital Sign found that 80.5% of patients scored as having low health literacy (score 0–3), whereas 19.5% had scores indicating adequate health literacy. Those with low health literacy were more likely to be of Hispanic ethnicity, Spanish-speaking, and have fewer years of education (Table 1). Only 22% of those with a high school education and 45% of those with at least some college education had adequate health literacy.
Of the 1,664 patients, only 516 (31%) had undergone screening mammography. The rate of mammography screening among women 40–49 years of age was 35% and the rate among women 50 years of age and older was 27%.
Mammography screening was significantly associated with health literacy. Among women aged 40–49 years, the rate of mammogram screening was 29% among those with low health literacy and 58% among those with adequate health literacy (P<.001). Among women 50 years of age and older, the rate of mammogram screening was 21% among those with low health literacy and 51% among those with adequate health literacy (P<.001).
Table 2 shows the rates of mammogram screening according to various sociodemographic variables. Unadjusted analysis found that Hispanic ethnicity and lack of insurance were associated with lower use of screening mammography. By contrast, younger age, non-Hispanic white race, English as primary language, family history of breast cancer, more years of education, adequate health literacy, current employment, nonsmokers, and higher income were associated with greater use of screening mammography. After adjustment for all of the aforementioned variables in a logistic regression analysis, we found that four factors were associated with not undergoing screening mammography: low health literacy (OR 0.27, 95% CI 0.19–0.37; P<.001), smoking (OR 0.64, 95% CI 0.47–0.85; P=.002), older age (OR 0.86, 95% CI 0.79–0.94; P=.001), and being uninsured (OR 0.66, 95% CI 0.51–0.85; P=.001).
Among patients who cited reasons for not undergoing a mammogram (n=740), the most common reasons were cost (35%), not feeling there was a problem with the breasts (47%), and not knowing it was necessary (10%; Fig. 2). Concerns about risks or overdiagnosis of screening mammography were very infrequent in this population. Only 2% of women felt mammograms were dangerous, did not work, or did not want to undergo mammography. Only 1% of women stated that their primary care provider did not recommend a mammogram for them. Concerns about the age to start screening were not common, because 0.7% felt they were too young to get a mammogram; however, all five of these patients were older than age 50 years.
The current study found that the use of screening mammography in our underinsured population was only 31%. Lack of insurance, older age, and being a smoker were associated with lower likelihood of undergoing screening. Health literacy, as measured by the Newest Vital Sign, was the variable most strongly associated with use of screening mammography. The majority of patients did not undergo screening because they did not have a problem with their breasts or did not know it was necessary, indicating a lack of understanding of the concept of screening. Therefore, tailored interventions for populations with limited literacy may have the potential to improve mammography screening rates like with other preventative services.25,26
Patients having low health literacy were significantly less likely to have undergone screening mammography than those with adequate health literacy (OR 0.27). Other factors that some might believe influence compliance with screening mammography such as age, Hispanic ethnicity, Spanish as primary language, fewer years of education, and lack of employment were not associated with mammogram screening in the multivariate analysis. More than one third (35%) of patients who did not undergo screening cited cost as the reason they did not participate. Our results showed that current smokers were less likely to undergo screening mammography. In recent years, there has been increasing evidence of an association between cigarette smoking and decreased compliance with physician recommendations. Current smokers have shown decreased compliance with all types of adjuvant therapy for breast cancer, medications after myocardial infarction, and adherence with bisphosphonates and human immunodeficiency virus medications.27–30
The finding that many (57%; Fig. 2) patients did not realize they should undergo screening indicates that information about mammography could be better tailored for low health literacy populations. Patients with low health literacy number more than 89 million in the United States and are present in all clinical practices.2,3 Many of these patients did not undergo mammograms because they did not have a problem with their breasts (ie, mass, pain), indicating that information to focus on the concepts of “screening” and prevention may improve compliance.25 In addition to informing patients that screening mammography is recommended, this information should state that medical insurance, including Medicaid, will cover screening mammography. As conditions of the Affordable Health Care Act become more integrated, many people who previously never had insurance may be unaware of covered services. Indeed, many patients in our study who cited cost as the reason for not obtaining a mammogram were actually insured by Arizona's Medicaid program. Arizona's Medicaid and Medicare programs do not require a copay or deductible for screening mammography. It is possible that a required copay or deductible in the 5% of patients with commercial insurance could have affected their ability to undergo screening; however, this was a small proportion of the population studied. The lack of understanding about the recommendations to obtain mammograms and that they are covered by insurance is an example of how patients with low health literacy are unable to effectively navigate the health care system and use preventive services. Recently there has been suggestion of increased risks of mammography; however, this did not appear to be a common belief in our population. Fewer than 3% of women stated that mammograms were dangerous, did not work, or not recommended by their clinician.
There are limitations to the current study that should be noted when interpreting the results. First, whether patients underwent screening mammography was determined by a review of documentation in the medical record. Although it is possible that some patients may have had mammograms at different facilities but were unable to recall the date or location, ascertainment of mammography screening from medical records is likely more accurate than patient self-reporting. In addition, when patients received mammograms outside our system, the reports were checked for availability of comparison films, which is routinely documented on mammogram reports. Therefore, we believe that our data on mammogram status are largely complete and correct. Second, the population was from a breast clinic rather than a primary care clinic and this may inadvertently select for patients more or less likely to have undergone screening compared with a primary care population.
Third, concern may exist about whether the results of the current study, which involves a significant proportion of Hispanic and Spanish-speaking patients, can be generalizable to other populations. Given that race–ethnicity, language, income, and other commonly assessed sociodemographic variables were not significant predictors of screening mammography, when health literacy status was considered in the analysis, suggests that this is not a concern.
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