Acute heart failure patients are more likely to die within two years of hospitalization if they have trouble understanding and using health information, according to a new study.

“Heart failure is a complicated condition,” said lead author Dr. Candace D. McNaughton of Vanderbilt University in Nashville, Tennessee. “Patients often have to take multiple medications, monitor (and count) their salt intake, and monitor their symptoms and weight daily. In some cases they even have to change the dosing of the medications in response to these.”

To do this, patients need to understand and use complicated medication information and numbers, she said.

In general, more than 30 percent of patients hospitalized for heart failure are rehospitalized or die within three months, the authors note in the Journal of the American Heart Association.

Researchers followed 1,379 patients who were hospitalized for acute heart failure and completed a brief health literacy screen at hospital admission between 2010 and 2013.

“To our knowledge, this is the first study in which health literacy was measured by nurses when patients were admitted to the hospital for heart failure,” McNaughton said.

“Nurses asked patients three questions: whether they have problems learning about their medical condition, their confidence filling out medical forms, and how often they have someone help them read hospital materials,” she said.

Almost 24 percent scored low enough on the screen to qualify for “low health literacy,” and almost 30 percent died during follow-up.

After accounting for the patients’ age, gender, race, insurance, education, other medical conditions and hospital length of stay, the researchers found that those with low health literacy were over 30 percent more likely to die than those who scored higher based on their self-reports.

Screen scores were not tied to rehospitalizations or ER visits.

“What we don´t know, and this study does not clarify either, is if this relationship is causal,” said Dr. Hector Bueno of the cardiology department at Hospital General Universitario Gregorio Marañón in Madrid, Spain.

Bueno was not involved in the new research.

About 5.1 million people in the U.S. have heart failure, when the heart cannot pump enough blood to support the rest of the body. Heart failure contributed to one of every nine deaths in the country in 2009, according to the Centers for Disease Control and Prevention.

“In general, the level of understanding of the causes, mechanism and course of the disease, triggers of decompensation and the role drugs and how these should be adjusted according to different situations required for an optimal self-care needs to be higher than for other chronic diseases,” Bueno told Reuters Health by email.

“One other important factor is that, compared with other chronic diseases –i.e. diabetes mellitus– heart failure is more frequent in elderly patients and we know that the level of general literacy is lower in older individuals,” he noted.

Patients should talk with their healthcare providers until they have a good understanding of how to take their medications, what the goals are for salt and water intake, as well as water weight, and how to balance all of this with other conditions such as diabetes, McNaughton said.

“Healthcare providers often overestimate their patients’ health literacy,” she said. “For many healthcare providers, it is often difficult to know which patients have low health literacy – for example, patients with graduate degrees can have difficulty understanding healthcare information because the information and language can be quite specialized.”

Healthcare providers can easily assess their heart failure patients’ health literacy with just three questions, McNaughton said by email.

“Really, though, all medical conditions require health literacy – everything from allergies to high blood pressure,” she said. “Health literacy, or the ability to use and understand healthcare information, is important for all patients, but the stakes are very high for patients with heart failure.”