Sentinel Health Event

A sentinel health event is the occurrence of a specific health condition, or the occurrence of an adverse outcome to a medical intervention, which signals that (a) the incidence of a condition or disease has exceeded the threshold of expected cases, (b) changes are occurring in the health levels of a population, or (c) the quality of medical care may need to be improved. Each of these circumstances may indicate the presence of a broader public health problem, and each requires epidemiologic investigation and intervention.

For example, the occurrence of a single case of smallpox anywhere in the world would signal the recurrence of a disease that has been eradicated in the wild, indicating that a highly unusual and unexpected event has occurred that requires immediate [Page 950]investigation. Likewise, an increase in the incidence of birth defects in a community that has had a stable incidence over time also indicates that the health level of that population has changed, possibly due to a change in the environment or due to a common exposure, which also warrants investigation. And when physicians began seeing cases of Kaposi's sarcoma, a very rare cancer seen almost exclusively in older men of Mediterranean or eastern European extraction, occurring in young American men, this was the harbinger of the presence of an entirely new condition, human immunodeficiency virus infection.

Sentinel health events have also been defined for use in monitoring health care settings for potential problems in health care quality. In this setting, the sentinel health event is an illness, disability, or death that was otherwise preventable or avoidable, except for a problem in health care delivery or quality. An increase in postoperative infections in a particular hospital or specific ward may indicate a problem involving individual operating room staff, ventilation systems, sterilization equipment, or other systems involved in the treatment and care of surgical patients.

To be able to identify when conditions or occurrences are unusual, good baseline information is required. Public health surveillance systems are used to gather such baseline data for a given population and facilitate the monitoring of sentinel health events.