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Adverse Events

Last Updated: 06-16-2022

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Key Terms

Patient Harm - Harm to a patient as a result of medical care or in a health care setting, including the failure to provide needed care. Patient harm refers collectively to adverse events and temporary harm events.

Adverse Event - An event in which care resulted in an undesirable clinical outcome-an outcome not caused by underlying disease-that prolonged the patient stay, caused permanent patient harm, required life-saving intervention, or contributed to death.

Temporary Harm Event - An event in which care resulted in patient harm and required medical intervention but did not prolong the patient stay, cause lasting harm, or require life-sustaining intervention.

All-Cause Harm - Patient harm, regardless of preventability or cause. OIG captures all-cause harm in its adverse event reports.

Every year, millions of Medicare patients experience adverse events and temporary harm events as a result of medical care or in a health care setting. These events can be the result of errors, substandard care, known side effects, or unexpected complications that may not have been preventable. Although most harm events resolve quickly, some have long-term and serious implications for patient health. Despite nationwide efforts to improve patient safety, reducing patient harm remains a challenge for the Department of Health and Human Services (HHS) and our Nation's health care providers. OIG is committed to helping HHS agencies determine the impact of harm events in Federal programs and supports new and existing efforts with recommendations to improve patient safety.

Initially prompted by a mandate in the Tax Relief and Health Care Act of 2006, OIG has produced a body of work related to patient safety and adverse events. This work includes publishing, in 2010, the first national incidence rate of adverse events among Medicare patients—27 percent of patients experienced some type of harm. To date, OIG has published 18 reports addressing topics ranging from the use of hospital incident reporting systems to labor and delivery in Indian Health Service hospitals. HHS agencies have implemented numerous OIG recommendations to broaden their patient safety efforts, including enhancing surveillance of adverse events and refining payment incentives to reduce the incidence of adverse events.

Patient Harm Is Common Among
Medicare Patients

In our most recent report, OIG released an updated national incidence rate of harm, finding that a quarter of Medicare patients (25 percent) experienced adverse events and temporary harm events during their hospital stays in October 2018. Many of these events (43 percent) could have been prevented through better care, and nearly a quarter of patients who experienced such events required care that resulted in additional costs to the Medicare program. Although changes to the methodology and to the Medicare population preclude a direct comparison to our earlier work, these findings show that patient harm remains a significant challenge in hospitals across the Nation.

Earlier reviews also raised concerns about the prevalence of harm in post-acute care facilities and in Indian Health Service hospitals, with harm rates ranging between 13 and 43 percent. In each setting, OIG found that harm events were often preventable and were costly to the Medicare program. In light of these findings and in response to our recommendations, HHS agencies took additional steps to further promote and incentivize patient safety.

OIG most recently recommended that HHS agencies reassess and update their efforts related to the National Strategy for Quality Improvement in Health Care, optimize national patient harm surveillance tools, and expand efforts to disseminate information about best practices and national clinical guidelines. OIG also recommended that HHS agencies take additional steps to align payment more effectively with quality and to provide guidance to surveyors that assess hospital compliance to track harm events.

Additionally, OIG is developing a toolkit to assist hospitals and other researchers working to identify adverse events and temporary harm events through medical record reviews. The toolkit will serve as a technical resource to assist the health care community, government agencies, and researchers in identifying and measuring adverse events and temporary harm events in hospitals.