Which statement best defines an adverse event in patient safety?

• A. An event that could have harmed but did not.
• B. An event that results in harm to the patient.
• C. An event outside the healthcare setting.
• D. An event that is planned and beneficial.

Answer: (B)

An adverse event is harm to a patient that results from the medical care they receive, not from the patient’s underlying illness. This harm is unintentional and can arise from treatment, procedures, medications, or systemic failures in care, and it may require extra treatment, extend hospital stay, cause disability, or lead to worse outcomes. This distinguishes it from a near miss—an event that could have caused harm but did not due to luck or timely intervention. It also differs from events outside the healthcare setting or from planned, beneficial interventions, which do not represent harm from medical care.