Table 2.
Variable Descriptions*
| Variable Name | Description |
|---|---|
| Curated Variables Based on Well Known Risk Factors (All Variables Collected During First 24 H of Admission) | |
| age_70 | (Time of Admission - Birthday) ≥70 years [8, 9, 11] |
| admission_source:TE | Transfer from nursing home [1] |
| day90_hospit | Recent hospitalization in the previous 90 days [7, 10] |
| hist_cdi | Previous CDI within the last year [11] |
| hemodialysis | Procedure code for dialysis [10] |
| gastro_tube | Procedure code associated with nasogastric or esophagostomy tube [16, 19] |
| ccsteroids | POE for corticosteroids [10] |
| immunosuppressants | POE for solid-organ transplant immunosuppressants |
| chemo_cdi | POE for chemotherapeutic agents associated with CDI |
| chemo_entero | POE for chemotherapeutic agents associated with enteropathy |
| antimicrobials_assoc | POE for antimicrobials frequently associated with CDI [9, 12–14, 20] |
| antimicrobials_rarely | POE for antimicrobials rarely associated with CDI [6] |
| ppi | POE for proton pump inhibitors [15, 17] |
| abdominal_surgery | Procedure codes for abdominal surgery associated with CDI [9, 18] |
| Variable Category | Description |
| Categories of Additional Variables Extracted From the EMR | |
| previous visits | Statistics on previous LOS (within 90 days) lengths (total, max, avg) |
| dxcodes | Highest level of ICD9 codes coded during most recent visit |
| labresults | Any laboratory test that was observed within 24 h with flag (high, low, critical) |
| vitals | All vitals with flags (high, low) collected during first 24 h |
| procedures | All procedure codes collected during first 24 h |
| medications | All POE for previous visit and during first 24 h of current visit |
| admission_type | Admission type |
| admission_source | Admission source |
| hospital_service | Hospital service |
| age | Discretized [15, 25, 45, 60, 70, 80, 100] |
| city | City where the patient resides |
| colonization_pressure | Unit and hospital-wide colonization pressure on day of admission |
Abbreviations: avg, average; CDI, Clostridium difficile infection; EMR, electronic medical record; LOS, length of stay; max, maximum; POE, physician order entry.
* We describe each patient admission using 2 sets of variables. We refer to the first set of variables as Curated. The second set of variables consists of all additional data procured from the structured fields of patients' electronic health records.