But the bill didn't gain traction and drew opposition from the Maryland Hospital Association.

Releasing the raw data for each hospital would discourage reporting, as the hospitals most aggressive about reporting would appear the least safe, said Carmela Coyle, president and CEO of the industry group. Instead, the information should be kept confidential and used to identify vulnerabilities in the system, she said.

"Hospitals work diligently on harm prevention," she said. "We know, and research shows, errors can and do happen. … But we need to move away from a culture of blame."

Del. Michael G. Summers, the Prince George's County Democrat who sponsored the bill, said he believes better reporting would reduce errors and empower patients when choosing a hospital. He said that he wanted to give hospitals more time to make progress behind the scenes and has not decided if he will reintroduce the bill.

Colorado and Minnesota are among the states that report hospital-level data publicly. Officials in those states believe the extra transparency has reduced errors and informed the public.

Minnesota's program was launched a decade ago to some hospital resistance, but Rachel Blake Jokela, the state's adverse health events program director, said that "as time goes on they see that this is an even playing field and all facilities are doing it."

On the federal level, Medicare has made limited data available on its website Hospital Compare to help consumers decide where to get care and encourage hospitals to improve.

But Dr. Martin Makary, a Hopkins associate professor of surgery who wrote the book "Unaccountable: What Hospitals Won't Tell You and How Transparency Can Revolutionize Healthcare," said that system isn't particularly useful for consumers.

"People should expect some measure of performance accountability from their hospitals, but too often performance is unmeasured, unavailable or unreliable," he said.

As part of the Affordable Care Act, Medicare and Medicaid officials began using billing data to penalize hospitals in 2012 for too many readmissions of heart and other patients. And in October, the hospitals will be fined when their patients obtain certain infections, bedsores, post-operative complications or other preventable conditions.

Meanwhile, Maryland hospitals are working to reduce medical errors and improve reporting. And the state has set a goal for them to reduce dozens of types of complications by 30 percent in the next five years as part of an arrangement with federal regulators.

The decision of when to notify hospital and state authorities is often difficult and less than straightforward, said Larry Raymond, clinical program manager of Howard County General Hospital's Center for Wound Healing, where most patients have complications, including those resulting from a mistake. He said the hospital has begun encouraging staff to report potential errors.

"We don't want to jump to any conclusions," he said. "We try and talk to doctors, and if we determine something is missed, we have a liaison in the hospital to help go through the events that could have caused direct harm to the patient. In most cases, there isn't obvious negligence."

Teaching the nuances of reporting medical errors at Greater Baltimore Medical Center is patient safety officer Carolyn Candiello's job. The hospital, cited in 2009 by regulators for failing to report that a 50-year-old patient developed a severe bedsore within 10 days of being admitted, has taken measures to step up disclosure, including hiring Candiello.

Two years ago, the hospital instituted an online incident-reporting system so staff could report concerns more easily and the information could be used to identify trends and improve hospital standards.

Last year the hospital also decided to voluntarily disclose some information about mistakes on its website each month, including charting the rate of "serious safety events." CEO John B. Chessare contends that while hospitals have been reluctant to share the data, disclosure can lead to improved care, and in turn, lower the risk of lawsuits and loss of business.

At Hopkins, Pronovost directs a hospital institute on patient safety and is working with institutions around the country to develop better reporting systems. But that will take time.

"For now, the data is squishy," he said.


Reporting an error

The public can report an error or complain about a facility by calling the state Office of Health Care Quality at 877-402-8218 or using an online form at dhmh.maryland.gov/ohcq