Ordering and getting results from medical tests is a problem in many family practice clinics, according to a new study, and the problem is especially bad for minority patients.

Researchers took anonymous reports from eight practices for 32 weeks. They received nearly 1,000 reports of problems with lab work, imaging and heart monitoring.

About one-quarter of the mistakes were a failure to get results to doctors. A failure to get the test and administrative errors each accounted for more than 17 percent of the problems.

The rate of what are called test implementation errors was nearly double for minority groups, at 32 percent versus 18 percent for whites. The authors of the study said this may reflect difficulties with transportation to the testing site or lack of insurance.

One-quarter of the errors resulted in delays in care for patients, and 13 percent caused pain or suffering. Eighteen percent resulted in harm.

"One of the most striking and disturbing findings was that minority patients were nearly three times more likely to experience adverse consequences," Dr. John Hickner said. They were also twice as likely to experience physical harm.

He also pointed out that the study was not meant to determine the real error rate, just to get a sense of the problem.

"Since many errors are undetected or unreported, we can assume this is an extreme lower bound," Hickner said.