Doctors discuss the cost of drugs only about a third of the time when they prescribe them to patients, U.S. researchers reported on Wednesday.

Doctors also failed to discuss important issues like getting refills, options for generics and insurance coverage, the researchers report in The American Journal of Managed Care.

"These can be important barriers to patient medication adherence," said Dr. Derjung Tarn of the University of California Los Angeles, who led the study.

Tarn's team looked at patient and doctor surveys and transcripts of 185 audiotaped patient visits at two health-care systems in California from January 1999 to November 1999.

These visits involved 15 family physicians, 18 internists and 11 cardiologists, who among them prescribed 243 new drugs.

In only 33 percent of the cases did the doctors talk about cost, insurance, generic or brand name, logistics, supply or refills. Patients asked about costs or insurance in only 2 percent of the cases.

Discussions about costs were more likely when the patient earned less than $20,000 a year, Tarn's team reported. Most of the patients had health insurance and more than three-fourths paid less than half of their prescription drug costs out-of-pocket.