Baseline health literacy is associated with better quality of life and improved disease control in asthma patients, researchers found.
For every point higher that they scored on a measure of health-related print literacy, patients had better asthma-related quality of life and asthma control, as indicated by a 0.63-unit increase (P=0.006) in the Mini-Asthma Quality of Life Questionnaire and a 0.52-point improvement (P=0.005) in the Asthma Control Questionnaire, according to Andrea Apter, MD, of the University of Pennsylvania in Philadelphia, and colleagues.
In addition, when individuals with moderate or severe persistent asthma scored one point higher on the Asthma Numeracy Questionnaire, a measure of asthma-related numerical ability, subsequent asthma-related quality of life was found to be better, as demonstrated by a 0.14-unit higher score (P=0.03) in the Mini-Asthma Quality of Life Questionnaire, they reported online in the Journal of Allergy and Clinical Immunology.
"This study supports the importance of considering patients' health literacy when clinicians communicate with patients," Apter and colleagues wrote. While numerous cross-sectional studies have linked health literacy and outcomes, the longitudinal design of this study suggested a more direct relationship.
"We found that baseline health literacy influences subsequent asthma control and quality of life," they wrote.
Apter and colleagues conducted their study within a larger randomized controlled trial called Individualized Interventions to Improve Adherence in Asthma. That trial found no difference in health outcomes between an individualized problem-solving strategy and standard asthma education in moderate or severe asthmatics.
For Apter and colleagues' trial, literacy questionnaires were added to the parent protocol approximately 6 months after recruitment in order to conduct the secondary analysis described in the study.
In the parent trial, patients with moderate or severe persistent asthma, as characterized by National Heart, Lung, and Blood Institute Expert Panel Report three guidelines, were recruited by researchers from Philadelphia area general and specialty clinics serving low-income communities with a high prevalence of asthma morbidity. These patients were then monitored for a period of 26 weeks.
After prescreening more than 49,000 patient charts, assessing for enrollment criteria and including only those who completed the parent study survey and literacy assessments, the researchers ultimately included 284 patients in their analysis. The average age was 48 years, 71% were women, 70% were African-American, and 65% were from households earning less than $30,000 per year.
Mixed effects linear regression models quantified the association of asthma outcomes – characterized by adherence to inhaled corticosteroid regimen as collected by electronic monitors, asthma control as determined by the 7-point scale of the Asthma Control Questionnaire, and asthma quality of life as assessed by the Mini-Asthma Quality of Life Questionnaire – with measurements of print and numeric literacy as measured by the 36-item the Short Test of Functional Health Literacy in Adults and four-item Asthma Numeracy Questionnaire, respectively.
In unadjusted models, researchers found print and numeric literacy significantly associated with adherence (P=0.08 and P=0.01, respectively), asthma control (P<0.001 and P=0.005, respectively), and quality of life (P<0.001 for both).
Race was strongly correlated with income and educational attainment, and its inclusion in adjusted regression models greatly diminished the degree of significance of the observed associations, highlighting the complex relationship between health outcomes and literacy, the authors noted.
"[T]he relationship between literacy and health is complex and this study is important for illustrating its complexity and pointing out that it is more than a cross-sectional association," they concluded. "Further research is required ... to develop effective interventions that will also address health disparities."
The strengths of the study include its prospective longitudinal design and the recruitment of patients from multiple clinical sites, the authors noted. Limitations included the limited duration, potentially imperfect reflection of health care navigation and access by the selected measurements of literacy, and difficulties associated with measuring adherence. Finally, as a secondary analysis, outcomes and data collection methods designed for the parent analysis may not have been optimal for this particular study.
Apter reported links with the National Heart, Lung and Blood Institute; the American Academy of Allergy, Asthma, & Immunology; AstraZeneca; Bristol-Myers Squibb; and UpToDate. Coauthors reported links with GlaxoSmithKline, Merck, National Institutes of Health, the Environmental Protection Agency, the National Cancer Institute, the Pennsylvania Department of Health, Xavier University, and the Children's Health Protection Advisory Board.
- Reviewed by Zalman S. Agus, MD Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner
Journal of Allergy and Clinical ImmunologySource Reference: Apter A "The association of health literacy with adherence and outcomes in moderate-severe asthma" J Allergy Clin Immunol 2013; DOI: 10.1016/j.jaci.2013.02.014