'Disturbing' Rate of Adverse Events During Hospital Stays: Report

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Jan. 12, 2023 – Nearly 1 in 4 people admitted to the hospital have an adverse event during their stay, and the events were less likely to happen at smaller hospitals compared to large ones, a new study shows. 

The findings were published today in the New England Journal of Medicine.

The report is “disturbing” and is a call to action for hospital leadership to prioritize patient safety, wrote Donald M. Berwick, MD, in an editorial accompanying the study. Berwick is president emeritus and a senior fellow at the Institute for Healthcare Improvement and a former administrator of the Centers for Medicare & Medicaid Services.

He noted that “‘first, do no harm’ remains a sacred obligation for all in health care.”

Adverse events were defined as “unintended physical injury resulting from or contributed to by medical care that requires additional monitoring, treatment, or hospitalization, or that results in death.” Seven deaths occurred among the cases studied, “one of which was deemed to be preventable,” the researchers reported.

Of the adverse events that occurred, 23% were preventable and 32% were categorized as serious.

For the study, researchers analyzed a random sample of 2,809 cases of people admitted to 11 Massachusetts hospitals in 2018. Trained nurses reviewed the records to identify adverse events using detailed criteria, including what are called “trigger” events, which previous research has shown often result in adverse events. Doctors then reviewed the adverse event summaries compiled by the nurses.

The most common events were:

  • Drug events, defined as “injuries resulting from drugs that were taken” (39%)
  • Surgical or other procedural events (30%)
  • Events related to nursing care such as falls and pressure ulcers (15%)
  • Health-care associated infections (12%)

The researchers found patterns in who was most likely to experience adverse events. Older patients were more likely to have adverse events than younger patients. Male patients were more likely to experience adverse events than female patients. 

Racial and ethnic differences were also observed. Patients who were Asian were less likely to have adverse events than Black or white patients, and Hispanic patients were less likely to have adverse events than non-Hispanic patients.

“These numbers are disappointing but not shocking,” study author David Bates, MD, told NBC News. “They do show we still have lots of work to do.”

The authors said limitations of their study included under-representation of patients whose primary insurance was Medicaid, and that their approach likely missed some adverse events.

The 11 hospitals that supplied data for the study all carried the same malpractice insurance carrier, which the authors reported “provided support” for the study as part of the company’s mission.

Show Sources


New England Journal of Medicine: “The Safety of Inpatient Health Care,” “Constancy of Purpose for Improving Patient Safety — Missing in Action.”

NBC News: “Nearly 1 in 4 U.S. hospitalized patients experience harmful events, study finds.”

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