Figure 1. Organization of patient tracking information.

Each patient is identified by a unique integer: the

uniquePid

. For each

uniquePid

, a patient may have distinct hospitalizations denoted by

patientHealthSystemStayId

. Finally, for each hospitalization, a patient may have distinct unit stays, denoted by

patientUnitStayId

.

patientUnitStayId

is the primary identifier used for linking data across tables.