The data element is based on the hospital's initial identification of Medicare EOC records for a measure set, stratum, or sub-population. Initial Patient Population Size – Medicare Only includes all patients that are billed under Medicare or Title 18. Medicare can be listed as a primary, secondary, teritary or lower on the list of payment sources for the patient. In addition, patients who are participating as a member of a Medicare HMO/Medicare Advantage are included in the Medicare counts, e.g., Medicare Blue, Humana Gold, Secure Horizons, AARP, Coventry Advantra, etc. This initial data pull utilizes administrative data such as ICD-9-CM diagnosis and procedure codes, admission date, and birthdate.

For the discharge measures (eg. HBIPS-1, 4, PC-01), refer to the Initial Patient Population discussion in the Measure Information section of this manual for more information.

For the HBIPS event measures (HBIPS-2 and 3), the Initial Patient Population Size – Medicare Only is equal to those EOC records in the census data identified as being Medicare EOC records. The HBIPS census data are calculated by (Psychiatric Inpatient Days-Medicare Only - Total Leave Days-Medicare Only). Initial Patient Population Size – Medicare Only is not derived from those cases that pass through the Initial Patient Population algorithm.

Note:
If the hospital’s data has been sampled, this field contains the population from which the sample was originally drawn, NOT the sample size.

Not Applicable