These requests were filed by MuckRock journalists Michael Nolan and Dillon Bergin.
Adverse events are medical errors and their consequences, an idea that captured the field of health care’s attention after the Institute of Medicine’s 1999 report that laid the problem of patient harm bare. The report sparked decades of nationwide efforts, but a recent Office of Inspector General report still found that “patient harm events in hospitals remain a serious concern.”
In 2005, the Patient Safety and Quality Improvement Act created a new system for health care organizations to report adverse events through the Agency for Health Care Research and Quality . AHRQ also created “common formats” that aim to standardize types of adverse events so that reporting across the country uses similar terms and definitions. Federal rules and policies like these outline how providers can report events that eventually make it into federal patient safety databases. The challenge is that this federal reporting is voluntary and can leave gaps in the types and amount of harm reported. A 2025 OIG report found that, similar to a study the office conducted in 2012, hospitals reported few patient harm events to Centers for Medicare & Medicaid Services or their state.
In 2018, the OIG surveyed state requirements for reporting adverse events and found that 26 states and the District of Columbia had reporting requirements. The type of requirements and reporting are different in each state. OIG found that requirements often focus on reporting the most serious types of harm and not all events. Some states, like Pennsylvania or California, have more robust reporting requirements. Pennsylvania created an independent state agency called the Patient Safety Authority, and describes itself as “the only state that requires health care facilities to report all instances of harm (i.e., serious events) or potential for harm (i.e., incidents).”
As of September 2026, the Data Liberation Project has received four state datasets in the form we requested and filed requests to 30 states. We’d like help requesting more data or appealing requests. You can get plugged in by joining MuckRock’s #public-data-liberation-project Slack channel.