CHICAGO -- A substantial proportion of patients may not be able to name the medications they take, which could affect both inpatient and outpatient care, researchers here found.
CHICAGO, Oct. 15 -- A substantial proportion of patients may not be able to name the medications they take, which could affect both inpatient and outpatient care, researchers here found.
Among even patients with adequate health literacy, 31.7% could not provide the name of a single antihypertensive drug in their records, Michael S. Wolf, Ph.D., M.P.H., of Northwestern here, and colleagues, reported in the November issue of the Journal of General Internal Medicine.
That inability rose to 59.6% among patients with poor health literacy, the investigators added.
Being unable to list medications and doses may complicate care for patients during treatment in the emergency department, inpatient, or safety-net setting, they said. An Institute of Medicine report found that medication errors in ambulatory care contribute the half a million adverse drug events that occur every year.
In the current study, the Northwestern researchers conducted interviews on medication use with 119 consecutive adults with diagnosed hypertension. They were seen at three primary care clinics from July 2005 through March 2006.
The average age was 55.3, and most of the patients were women (69.5%) and black (60.5%). Nearly 40% had completed less than a high school education, but only 31.1% of patients had inadequate health literacy as evaluated with the short version of the Test of Functional Health Literacy in Adults.
Nearly all the patients had at least one blood pressure lowering medication listed in their medical record-- 31.1% one, 32.8% two, and 29.4% three or more.
Overall, 40.3% of patients could not name any of the antihypertensive medicines in their chart, 37.0% could correctly name only one of the drugs, and only 22.7% of patients could name two or more.
Those with poor health literacy were able to name significantly fewer of their blood pressure lowering medications overall (P=0.03).
There was a 3.2-fold (95% confidence interval 1.4 to 7.1) difference between the ability patients with inadequate health literacy to name any of their antihypertensive medications and those with adequate health literacy (59.5% versus 31.7%).
The association with health literacy persisted after adjustment for age and income (OR 2.9, 95%CI 1.3 to 6.7) and was not changed substantially by further controlling for race and education.
Agreement between antihypertensive medications reported by patients and the medical record was relatively low with no medications in common between lists in 46.2% of cases and partial agreement in 24.4%.
Again, patients with poor health literacy were more likely to be completely at odds with their chart than those with adequate health literacy (64.9% versus 37.8%).
Although no significant differences were seen in blood pressure by health literacy, those with poor health literacy tended to be less likely to have blood pressure below 140/90 mm Hg (59.1% versus 70.7%, P=0.096).
"Our finding that inadequate health literacy was associated with having two or more antihypertensive medications recorded in the medical record but not with the number of antihypertensive medications patients reported taking
The number of antihypertensive medications patients reported taking was not correlated with health literacy overall (P=0.34) or for those who reported taking two or more (P=0.35).
However, patients with poor health literacy were more likely to be prescribed two or more drugs (P=0.004), which "could indicate a relationship between inadequate health literacy and nonadherence in this population," Dr. Wolf and colleagues wrote.
Doctors may prescribe more medications because patients incorrectly remember or report what medicine they are already taking, the investigators suggested.
"Future research should examine in detail the relationship between health literacy, medication discrepancies, and chronic disease outcomes," they concluded.
Dr. Wolf reported having received research funding from Target Corp., and Pfizer Pharmaceuticals for health literacy-related intervention studies.