Association of Health Literacy with Elevated Blood Pressure in Hospitalized Patients

Background:

Undiagnosed and uncontrolled hypertension are prevalent public health issues. Their relationship with low health literacy, which affects approximately 36% of adult Americans, is not well studied. We evaluated the relationship between low health literacy and elevated blood pressure at hospital presentation.

Methods:

We conducted a cross‐sectional evaluation of adult patients hospitalized at Vanderbilt University Hospital between November 1, 2010 and April 30, 2012. Health literacy was assessed routinely by clinical nursing staff using the Brief Health Literacy Screen (BHLS), which consists of 3 self‐report questions. Low health literacy was defined as a BHLS score ≤ 9. Blood pressure was assessed using clinical measurements. The primary outcome was elevated blood pressure (≥ 140/90 mmHg, or ≥ 130/80 mmHg for patients with diabetes or renal disease) at the time of hospital presentation. A secondary outcome was extremely elevated blood pressure (≥ 160/100 mmHg). Logistic regression was performed, adjusting for age, gender, race, insurance type, co‐morbid conditions, prescribed antihypertensive medications, and patient‐level clustering. Pre‐planned subgroup analyses based on prior diagnosis of hypertension were performed.

Results:

Of the 46,263 hospitalizations included, 23% had low health literacy on the BHLS. Low health literacy hospitalizations occurred among patients who were older (61 vs. 54 years), less educated (28.4% vs. 11.2% had not completed high school), and more often admitted through the emergency department (54.3% vs. 48.1%) than those with a BHLS > 9. Among those with low health literacy, 40.0% had an elevated blood pressure compared to 35.5% among those with a BHLS > 9 (adjusted Odds Ratio [aOR] 1.06, 95% CI 1.01, 1.12). Low health literacy was also associated with extremely elevated blood pressure at presentation (aOR 1.08, 95% CI 1.01, 1.16). The relationship of low health literacy with elevated blood pressure was primarily seem among those without a previous diagnosis of hypertension (aOR 1.09, 95% CI 1.02, 1.16).

Conclusions:

More than 1/3 of patients had an elevated blood pressure at hospital presentation. Low health literacy was independently associated with elevated blood pressure, particularly among patients without a previous diagnosis of hypertension.