Doctors in the United States fail to tell patients about abnormal test results 7 percent of the time, or a rate of about 1 out of every 14 tests, U.S. researchers said on Monday.

They said electronic medical records -- touted by President Barack Obama and many experts as a way of reducing errors -- did not reduce and, in some cases, slightly increased the chances for these kinds of mistakes, they said.

The electronic medical record doesn't magically fix the problem, said Dr. Lawrence Casalino of Weill Cornell Medical College in New York, whose study appears in the Archives of Internal Medicine.

Not telling patients about abnormal test results can delay treatment of cancers or heart disease, hurting the patient's chances of survival and exposing doctors to malpractice lawsuits.

Failure to diagnose is one of the most common causes of malpractice suits, Casalino said in a telephone interview.

Casalino and colleagues analyzed more than 5,000 patient records from 23 physician practices across the country, looking at screening tests for conditions such as high cholesterol, diabetes, blood tests for colon cancer and mammograms.

They found doctors failed to inform patients 7.1 percent of the time. Performance at individual practices varied widely. Some practices always informed patients, and some failed to inform patients 26 percent of the time.

Physician offices that used a combination of paper and electronic records -- a so-called partial electronic medical record -- had the highest failure rates, while there was no significant difference between practices that only used electronic medical records or paper records.

Casalino said doctors should have explicit rules for informing patients of test results. He said all results should be sent back to the doctor who ordered them, and patients should be told the results of all tests, even if they are normal.

He said patients should make sure they ask their doctors for the results of all tests. Don't ever assume that no news is good news, Casalino said.