Half of all heart patients made at least one medication-related mistake after leaving the hospital, and guidance from a pharmacist didn't seem to reduce those errors, in a new study.

Consequences of mistakes - such as forgetting to take certain drugs or taking the wrong dose - can range from side effects like constipation to more serious drops in blood pressure. Two percent of errors were life-threatening.

Not all of the problems, however, were the fault of the patients. Some may have resulted from medication side effects or other factors beyond patients' control.

Hospitals involved in the study were already taking steps to prevent medication mistakes in addition to the extra pharmacist intervention, said Dr. Sunil Kripalani, the study's lead author from the Vanderbilt University Medical Center in Nashville, Tennessee.

"We were surprised to see that in spite of these efforts that 50 percent (of patients) were still having these medication errors," he told Reuters Health.

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Although the pharmacist visits didn't help the average patient, he added, certain ones seemed to benefit - such as patients who were on multiple drugs or had trouble understanding health information.

As for traditionally lower-risk patients, he said other strategies to prevent errors may be needed.

One-on-one meetings

For their study, Kripalani and his fellow researchers followed patients who had been hospitalized for heart conditions at Vanderbilt University Hospital and Brigham and Women's Hospital in Boston.

Half of the patients were randomly assigned to attend two visits with a pharmacist, who looked at which medications patients were taking and instructed them on what to do once they left the hospital to manage their prescriptions and reduce side effects.

The patients also received tools, such as a medication chart and pillbox, to use at home.

After leaving the hospital, the patients received a phone call within a few days from one of the study's coordinators who was able to identify medication-related problems over the phone. If any were found, a pharmacist made a follow-up call.

The other heart patients did not receive any special treatment outside of normal hospital procedure, which is for a nurse or doctor to spend a few minutes with patients before they leave the hospital to discuss their medications.

One month later, 432 out of the 851 patients had made at least one harmful or potentially-harmful medication error, including missing doses, taking the incorrect dose, stopping a drug too early or continuing it for too long.

Just under one-quarter of those errors were judged to be serious and about two percent were life-threatening. And there was no difference in the number of errors made by patients who did or didn't get extra pharmacist advice.

One limitation, the researchers note in their Annals of Internal Medicine report, is that not all patients in the intervention group had two pharmacist visits or a follow-up call as intended. It's also unclear whether the findings would apply to patients being treated for other, non-heart conditions.

Keep a list

Kevin Boesen, director of the Medication Management Center at the University of Arizona College of Pharmacy in Tucson, told Reuters Health he's not surprised that many people are confused after leaving the hospital.

"To me, I think (the finding) highlights the challenge for the transition from hospital to home," he said.

Boesen added that it's important for patients to meet with their regular pharmacist and primary care doctor after they get out of the hospital or fill a prescription somewhere else.

"I think there is the assumption that when a patient goes to a pharmacy the pharmacist will have a list of all the medication they're on," he said. But that's not always the case.

A key safety step patients can take, Boesen and Kripalani agreed, is to keep track of all of the drugs they're taking and carry a list.

"The single most important thing patients and families can do to promote safety with their medications is to always keep a medication list with them," Kripalani said. That list should include drug doses and patients' reason for taking each medication, he added.

"If a patient simply carries that medication list, so everyone is working off of one list, that definitely helps," said Boesen.