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OBJECTIVE: To test the significance of health literacy relative to other predictors of adherence to treatment for HIV and AIDS.
PARTICIPANTS: Community sample of HIV-seropositive men (n = 138) and women (n = 44) currently taking a triple-drug combination of antiretroviral therapies for HIV infection; 60% were ethnic minorities, and 73% had been diagnosed with AIDS.
MEASUREMENTS: An adapted form of the Test of Health Literacy in Adults (TOFHLA), a comprehensive health and treatment interview that included 2-day recall of treatment adherence and reasons for nonadherence, and measures of substance abuse, social support, emotional distress, and attitudes toward primary care providers.
MAIN RESULTS: Multiple logistic regression showed that education and health literacy were significant and independent predictors of 2-day treatment adherence after controlling for age, ethnicity, income, HIV symptoms, substance abuse, social support, emotional distress, and attitudes toward primary care providers. Persons of low literacy were more likely to miss treatment doses because of confusion, depression, and desire to cleanse their body than were participants with higher health literacy.
CONCLUSIONS: Interventions are needed to help persons of low literacy adhere to antiretroviral therapies.
Combination antiretroviral therapies for HIV infection have demonstrated efficacy in improving immune function, reducing viremia, and reducing HIV-related morbidity and mortality. However, the promises of revolutionary HIV-AIDS treatments also bring significant challenges. Highly active antiretroviral therapy (HAART) includes complex regimens that require strict adherence to complicated treatment schedules. Of great concern are treatment-resistant variants of HIV that rapidly develop in response to underdosing and intermittent, irregular use of antiretroviral agents. 1 Factors that negatively influence adherence to HAART therefore pose considerable threats to both individual and public health.
Several factors related to adherence to reverse transcriptase inhibitor regimens were reported before protease inhibitors became available. 2 As many as one third of patients taking reverse transcriptase inhibitors, particularly zidovudine, may discontinue their use, 3 and one third may intentionally alter prescribed doses. 4 Failing to adhere to treatment can result from forgetting, lack of motivation, and intolerance of side effects. Treatment nonadherence can also be a response to the burdens of complicated drug regimens that disrupt one’s daily routine. 5 Among persons studied in one AIDS clinical trial, missed doses of antiretroviral agents were most likely to occur because of forgetting (43%), sleeping through a dose (36%), being away from home (32%), changing one’s routine (27%), being too busy to take the dose (22%), feeling sick (11%), and experiencing depression (9%). 6 People who refuse to take antiretroviral therapy commonly state that they believe the drugs are ineffective and toxic. 7 Social support is associated with adhering to antiretroviral therapy, with greater social support predicting more consistent adherence. 8 Another key factor in medication adherence is the relationship between patient and primary care provider. Patients who trust their provider and are satisfied with their quality of care are more likely to adhere to treatment regimens. 9,10
Substance abuse also raises concerns about antiretroviral treatment owing to the cognitive and behavioral disturbances common in substance-abusing populations. For example, Singh and colleagues found that HIV-seropositive patients with a history of injection drug use were more likely to be nonadherent to antiretroviral therapy than were those who had not used injection drugs. 11 Nonadherent patients also were more likely to experience symptoms of depression and lacked adaptive coping strategies. Broers et al. reported that injection drug users delayed initiating anti-HIV treatment, but were adherent once treatment was started. 12 O’Connor and Samet suggested that substance-abusing patients have a host of problems, including resistance to comply with instructions, potential drug interactions, and conditions of living in poverty, that present considerable challenges to medical management of HIV infection. 13
In the current study, we examined adherence to antiretroviral therapies in a community sample of men and women living with HIV-AIDS. Although a number of variables influence adherence to non-HIV treatments, many of which have been associated with adherence to zidovudine therapy among people living with HIV-AIDS, these factors are currently being examined in adherence to HAART. Among other influences of treatment adherence, we were particularly interested in the patient’s ability to comprehend medical information and the association between literacy skills and HIV treatment adherence. Health literacy is frequently below functional levels in medical populations, and people with lower health literacy often experience poor health and negative treatment outcomes. 14,15 Understanding medical instructions is a necessary, although for many not sufficient, condition for treatment adherence. To our knowledge, this is the first study to examine health literacy, a more sensitive and specific index of understanding medical instructions than general education level, among factors related to antiretroviral therapy adherence. We hypothesized that health literacy would significantly predict adherence to antiretroviral regimens over and above other well-established predictors of treatment adherence. If confirmed, this would indicate that interventions to improve adherence must be adjusted to accommodate reading and comprehension skills of people with low literacy.
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Results of this study must be interpreted in light of its methodologic limitations. The study was conducted in a community setting rather than a clinic. The advantage of studying persons who may be marginally connected to HIV treatment services and not enrolled in drug trials came at the cost of relying on self-report measures of health status and treatment regimens. Although our measures appeared internally reliable (e.g., people who were nonadherent had lower CD4 cell counts and were less likely to have undetectable viral loads), the degree to which participants provided accurate health information is unknown. Although HIV symptoms and stage of disease were not associated with health literacy, we did not formally assess neurocognitive impairment in this study, a factor that could interfere with remembering treatment regimens and may have affected performance on the literacy scales. Another factor that may have influenced our results is the differential treatment that providers may give to persons with low literacy skills. For example, providers may not give the same level of detailed instructions to patients who experience comprehension difficulties. Future research should therefore examine different practices of instructing patients with low and higher literacy. In addition, we only collected measures at a single assessment session, prohibiting us from making the kind of predictions over time that prospective studies afford. Finally, our sample was partly recruited through flyers describing the study, a method that may have failed to reach people of the lowest literacy; thus, our sample may have underrepresented this group of people who may be experiencing the greatest difficulty adhering to medication regimens. Our findings must therefore be considered a conservative estimate of literacy and its association with antiretroviral adherence among people living with HIV-AIDS.
One in five persons on HAART in the current study were nonadherent to their treatment regimen in the previous 2 days, a rate similar to that in other studies. 18 As has occurred with multiple drug-resistant strains of tuberculosis that resulted from irregular and inconsistent use of antibiotics, 19 nonadherence to HAART threatens to undermine the promise of effective HIV-AIDS treatments. Failure to adhere to treatment schedules is particularly troublesome with protease inhibitors because of HIV’s ability to rapidly develop resistance to these drugs. Virus-resistant mutations can develop after only days of intermittent protease inhibitor use, and reverse transcriptase inhibitors are not much more forgiving. Identifying factors associated with nonadherence to antiretroviral therapy must, therefore, inform interventions designed to assist people undergoing HAART.
The current study found that factors associated with nonadherence to other treatments were also associated with nonadherence to HAART. Univariate analyses indicated that ethnic minorities, persons who perceived receiving less social support, and those experiencing greater emotional distress were more likely to have been nonadherent in the past 2 days. Surprisingly, substance use and attitudes toward providers were not significantly associated with adherence in this study. However, our measures of substance use reflected global patterns of use for the previous 3 months whereas adherence was defined over a 2-day period. Thus, the association between substance use and treatment adherence may have been obscured by our desynchronized measures.
Both univariate and multivariate tests showed that years of education and health literacy were significant independent predictors of treatment adherence. People of lower education and lower literacy were between 3 and 4 times more likely to have missed a dose of antiretroviral medications in the previous 2 days. Income level, ethnic background, and HIV disease progression did not account for these associations. Consistent with these findings, people of lower literacy were more likely to have missed a dose of their medications because they were confused about their treatment regimen, were depressed, or desired to cleanse their body of treatments. Thus, we conclude that education level and, perhaps more importantly, health literacy are important in adherence to combination antiretroviral regimens, and both must be considered in designing patient materials and strategies for enhancing antiretroviral treatment adherence. Low education itself is a reasonable marker for potential nonadherence. However, for persons with at least 12 years of education, it is necessary to assess their literacy to identify the risk of nonadherence.
Although treatment regimens for HIV-AIDS are becoming less complex with the advent of combined drugs in single medications and through twice-a-day and once-a-day dosing, literacy will most likely remain an important barrier to long-term treatment adherence even for the simplest regimens. 14,15 Interventions to increase adherence to treatment schedules have relied on daily calendars, outlines of meal schedules, reminder notes, condensed instructions for dietary considerations, and charts for dosing schedules. 20,21 Devices such as timers and alarms have also been suggested to increase adherence to antiretroviral therapy. 22 Unfortunately, many of these strategies require literacy skills and other resources that people who may be at greatest risk of nonadherence lack. Also, persons with low literacy skills were no more likely to experience forgetfulness or distractions in missing their medications than were persons of higher literacy, suggesting that memory aides may not address the intersection between low literacy and nonadherence. Therefore, interventions to assist people in adhering to antiretroviral therapies must be adapted for persons of lower literacy with specific attention given to relevant treatment barriers.
People of lower literacy may benefit from pictorial displays of their medications, accurate in color and size, with graphic illustration of the instructions including the number of pills to be taken, and at what times. In addition, videotapes tailored to different levels of comprehension may provide a more effective medium than pamphlets and brochures for educating patients about their treatments. Intensive case management and assertive assistance programs may be required for those persons with the greatest difficulty understanding their treatment regimen and the importance of adherence. 23 Finally, and perhaps most importantly, primary care providers must tailor their instructions to match the capabilities of their patients. For example, low education and low literacy suggest the importance of including concrete practice exercises with lots of repetition. The necessity of attending to low literacy in patients undergoing HIV-AIDS treatment will become increasingly pressing as the HIV epidemic spreads to impoverished areas of developed countries and as antiretroviral treatments become increasingly available in developing countries. Designing effective interventions to promote treatment adherence in persons of lower literacy must, therefore, be considered a high priority in national AIDS treatment agendas.