TUESDAY, Nov. 29 (HealthDay News) -- Nearly 40 percent of American seniors who receive medical care from a home health agency take at least one prescription drug that is potentially unsafe or ineffective for them, according to a new study.

That rate is nearly three times higher than for seniors who get their prescriptions when visiting a medical office, said study leader Dr. Yuhua Bao, an assistant professor of public health at Weill Cornell Medical College, and colleagues.

The researchers also found that home health care patients aged 65 and older take an average of 11 medications and that this use of multiple drugs is a strong indicator of the presence of potentially inappropriate medications.

For the study, the researchers analyzed data from more than 3,100 home health care patients aged 65 and older who were included in the 2007 National Home and Hospice Care Survey and found that 38 percent of those patients took at least one potentially inappropriate medication.

Patients taking 15 or more medications were five to six times more likely to be prescribed potentially inappropriate medications than those taking seven or fewer drugs. Of the patients taking at least one potentially inappropriate medication, 21 percent took 15 or more medications.

"Elderly patients receiving home health care are usually prescribed medications by a variety of physicians, and it's a great challenge for home health care nurses to deal with prescriptions from many sources," Bao said in a medical college news release.

However, she said home health care also offers a potential solution.

"Having a medical professional enter an elderly patient's home is an opportunity to do a proper medication review and reconciliation," Bao explained.

The study was released online in advance of publication in an upcoming print issue of the Journal of General Internal Medicine.

More information

The AGS Foundation for Health in Aging offers advice about the safe use of medicines at home.