Numeracy, Health Literacy, Cognition, and 30-Day Readmissions among Patients with Heart Failure
BACKGROUND: Numeracy, health literacy, and cognition are important for chronic disease management. Prior studies have found them to be associated with poorer self-care and worse clinical outcomes, but limited data exists in the context of heart failure (HF), a condition that requires patients to monitor their weight, fluid intake, and dietary salt, especially in the posthospitalization period.
OBJECTIVE: To examine the relationship between numeracy, health literacy, and cognition with 30-day readmissions among patients hospitalized for acute decompensated HF (ADHF).
DESIGN/SETTING/PATIENTS: The Vanderbilt Inpatient Cohort Study is a prospective longitudinal study of adults hospitalized with acute coronary syndromes and/or ADHF. We studied 883 adults hospitalized with ADHF.
MEASUREMENTS: During their hospitalization, a baseline interview was performed in which demographic characteristics, numeracy, health literacy, and cognition were assessed. Through chart review, clinical characteristics were determined. The outcome of interest was 30-day readmission to any acute care hospital. To examine the association between numeracy, health literacy, cognition, and 30-day readmissions, multivariable Poisson (log-linear) regression was used.
RESULTS: Of the 883 patients admitted for ADHF, 23.8% (n = 210) were readmitted within 30 days; 33.9% of the study population had inadequate numeracy skills, 24.6% had inadequate/marginal literacy skills, and 53% had any cognitive impairment. Numeracy and cognition were not associated with 30-day readmissions. Though (objective) health literacy was associated with 30-day readmissions in unadjusted analyses, it was not in adjusted analyses.
CONCLUSIONS: Numeracy, health literacy, and cognition were not associated with 30-day readmission among this sample of patients hospitalized with ADHF.
© 2018 Society of Hospital Medicine
Most studies to identify risk factors for readmission among patients with heart failure (HF) have focused on demographic and clinical characteristics.1,2 Although easy to extract from administrative databases, this approach fails to capture the complex psychosocial and cognitive factors that influence the ability of HF patients to manage their disease in the postdischarge period, as depicted in the framework by Meyers et al.3 (2014). To date, studies have found low health literacy, decreased social support, and cognitive impairment to be associated with health behaviors and outcomes among HF patients, including decreased self-care,4 low HF-specific knowledge,5 medication nonadherence,6 hospitalizations,7 and mortality.8-10 Less, however, is known about the effect of numeracy on HF outcomes, such as 30-day readmission.
Numeracy, or quantitative literacy, refers to the ability to access, understand, and apply numerical data to health-related decisions.11 It is estimated that 110 million people in the United States have limited numeracy skills.12 Low numeracy is a risk factor for poor glycemic control among patients with diabetes,13 medication adherence in HIV/AIDS,14 and worse blood pressure control in hypertensives.15 Much like these conditions, HF requires that patients understand, use, and act on numerical information. Maintaining a low-salt diet, monitoring weight, adjusting diuretic doses, and measuring blood pressure are tasks that HF patients are asked to perform on a daily or near-daily basis. These tasks are particularly important in the posthospitalization period and could be complicated by medication changes, which might create additional challenges for patients with inadequate numeracy. Additionally, cognitive impairment, which is a highly prevalent comorbid condition among adults with HF,16,17 might impose additional barriers for those with inadequate numeracy who do not have adequate social support. However, to date, numeracy in the context of HF has not been well described.
Herein, we examined the effects of numeracy, alongside health literacy and cognition, on 30-day readmission risk among patients hospitalized for acute decompensated HF (ADHF).
METHODS
Study Design
The Vanderbilt Inpatient Cohort Study (VICS) is a prospective observational study of patients admitted with cardiovascular disease to Vanderbilt University Medical Center (VUMC), an academic tertiary care hospital. VICS was designed to investigate the impact of social determinants of health on postdischarge health outcomes. A detailed description of the study rationale, design, and methods is described elsewhere.3
Briefly, participants completed a baseline interview while hospitalized, and follow-up phone calls were conducted within 1 week of discharge, at 30 days, and at 90 days. At 30 and 90 days postdischarge, healthcare utilization was ascertained by review of medical records and patient report. Clinical data about the index hospitalization were also abstracted. The Vanderbilt University Institutional Review Board approved the study.
Study Population
Patients hospitalized from 2011 to 2015 with a likely diagnosis of acute coronary syndrome and/or ADHF, as determined by a physician’s review of the medical record, were identified as potentially eligible. Research assistants assessed these patients for the presence of the following exclusion criteria: less than 18 years of age, non-English speaking, unstable psychiatric illness, a low likelihood of follow-up (eg, no reliable telephone number), on hospice, or otherwise too ill to complete an interview. Additionally, those with severe cognitive impairment, as assessed from the medical record (such as seeing a note describing dementia), and those with delirium, as assessed by the brief confusion assessment method, were excluded from enrollment in the study.18,19 Those who died before discharge or during the 30-day follow-up period were excluded. For this analysis, we restricted our sample to only include participants who were hospitalized for ADHF.
