NEW YORK - Malpractice claims for medical errors are common outside hospitals, according to a US study that highlights safety problems at doctors' offices as well.

Previous studies have focused mainly on hospitals, some of which now have checklists in place to help prevent mistakes.

But researchers led by Tara Bishop, at Weill Cornell Medical College in New York, found that about half of all US malpractice payments from 2009 involved patients seen outside the hospital.

With "invasive and high-technology diagnostic and therapeutic procedures ... increasingly being performed in the outpatient setting", Bishop and her team decided to compare the number and seriousness of adverse events in inpatient and outpatient settings, as reflected by malpractice claims.

What they found, that the number of malpractice claims would be virtually the same for hospitals and doctors' offices, was unexpected.

"We were actually very surprised by that finding," Bishop said of their report, published in the Journal of the American Medical Association.

"I hope it's a wake-up call for the medical community and for patients, so we can start working on ways to solve these problems."

The researchers analyzed malpractice claim payments from the National Practitioner Data Bank from 2005 to 2009. Overall, the number of payments dropped slightly for patients treated both inside and outside hospitals.

But in 2009, the last year of the study, there were 4,910 payments due to inpatient errors, 4,448 due to outpatient errors, and 966 involving both settings. Together, these payments were worth more than $3.3 billion.

"These weren't trivial errors - death and major injuries were the most common reason for malpractice claims," said Bishop.

"It's nice to see this trend coming down, but we still don't know if it's due to better patient safety."

According to the report, there were 30 times as many outpatient visits as hospital discharges every year.

Bishop said the most common errors were different. Surgical mistakes dominating the claim for hospitalized patients and misdiagnosis was the biggest problem at the doctor's office.

That means fixing problems outside hospitals will take separate efforts, such as training doctors to communicate better with patients.

Other experts said that the malpractice claims were probably only a small part of medical errors and that, unfortunately, a good program for controlling the risk of outpatient errors doesn't yet exist.

Reuters