March 21 (HealthDay News) -- Medication errors are common and often difficult to detect in patients receiving outpatient care after an organ transplant, U.S. researchers find.

Reporting in the March issue of the journal Archives of Surgery, a team at the Yale University School of Medicine identified 149 medication errors in 93 liver, kidney and pancreas transplant patients who were taking an average of about 11 medications each.

Patient error was the most common type of medication error (56 percent), followed by: prescription errors and delivery errors (both 13 percent); availability errors -- patients did not have at least a 24-hour supply of medication (10 percent); and reporting errors -- the patient could not give researchers enough information to identify the type, dosage or frequency of a medication (8 percent).

The study also found that 48 (32 percent) of the errors resulted in adverse events, including 17 hospitalizations, three outpatient procedures, nine episodes of rejection, and six failed transplants.

The root causes of the medication errors were the patient (68 percent); health care providers (27 percent, including 10 percent by transplant team); and financial issues (five percent).

The study authors noted that medication errors are often the result of communication breakdowns.

"We should strive to continue to eliminate health care system-based errors through centralized records and other streamlining methods to improve processes. In doing so, it seems likely that our patients will gain confidence in us and our ability to help them navigate a complex and confusing system," the study authors wrote.

This would improve patient safety and promote a shift from a culture of blame to a culture of prevention, they noted.