Define Population of Interest
Parameters to consider:
- Encounter type (for research questions limited to patient location)
- Type of admission (e.g. inpatient, outpatient, surgery)
- Patient characteristics
- Patient demographics (e.g. age)
- Time frame
- All available records
- Within a specific timeframe (YYYY-MM-DD to YYYY-MM-DD)
- For variables that may have multiple entries per patient (e.g. multiple glucose measurements per hospitalization), you can request: only the last entry, the first entry, or all entries for the visit
- An index event
- All patients with a specific ICD9 code
- CPT procedure code
- Lab entry (e.g. fasting glucose)
- Supply codes (when possible) for medical entities requested.
- For example, if requesting all patients with a diagnosis of hypertension, supply the ICD9 code “401.”
- The following are appropriate terminologies for various entities:
- Diagnoses: ICD9
- Procedures: ICD9 or CPT code
- Labs: MED codes if possible
- The East, West, and Allen campuses all use separate codes for labs, so you may need to clarify your request with a programmer once one has been assigned to you.
- For any request, MED codes are also highly encouraged to be included.
Tip: Using the RedX query combiner tool can get you a rough idea on sample size within the CDW. Since RedX is a 5% random sample, your eventual sample size would be approximately the sample size from RedX times 20.