Table 2.
Summary Description of All Model Covariates in Study of CDI as a Proxy for Length of Stay
| Variable | Description/specification |
|---|---|
| Hospital characteristics | |
| Bed size | Small, medium, or large |
| Control/ownership | Public, private (nonprofit), private (for profit) |
| Region | Northeast, Midwest, South, West |
| Teaching status/location | Rural, urban nonteaching, urban teaching |
| RN percent | Percentage of RNs among all licensed nurses |
| Nurse to patient ratio | Number of total licensed nurse full-time equivalents per 100 inpatient-days |
| Patient characteristics | |
| Age group | 21 indicators for 5-year age ranges |
| Sex | Female or male |
| Race | White, black, Hispanic, Asian or Pacific Islander, Native American, or other |
| Admission type | Emergency, urgent, elective, newborn, trauma center, other |
| Disposition | 6 indicators for routine, transfer to short-term hospital, other transfer, home healthcare, against medical advice, or unknown |
| OR procedure | Indicator of major OR procedure |
| Neonatal or maternal diagnosis/procedure | Indicators for maternal, neonatal, or both maternal and neonatal records |
| Admission month | 12 monthly indicators |
| Admission weekend | Indicator of weekend admission |
| Died | Indicator of hospital death |
| Comorbidities | 29 comorbid disease indicatorsa |
| Number of procedures | 30 indicators for the total number of procedures coded on discharge record |
| Number of diagnoses | 30 indicators for the total number of diagnoses coded on discharge record |
| Number of chronic conditions | 30 indicators for the total number of unique chronic diagnoses reported on the discharge |
| APR DRGsb | 316 APR DRG indicators |
| APR DRG risk mortalityb | 4 indicators for likelihood of dying: minor, moderate, major, or extreme |
| APR DRG severityb | 4 indicators for severity of illness (loss of function): minor, moderate, major, or extreme |
| Primary expected payer | Medicare, Medicaid, private insurance, self-pay, no charge, or other |
| ZIP code median income | 4 quartile indicators for estimated median household income in patient’s ZIP code |
Note. APR, All Patient Refined; CDI, Clostridium difficile infection; DRG, diagnosis-related groups; OR, operating room; RN, registered nurse.
a
The 29 comorbidity indicators were assigned by the Agency for Healthcare Research and Quality Comorbidity Software, version 3.7.
b
The variables for APR DRGs along with APR DRG severity and APR DRG risk mortality were created using software developed by 3M Health Information Systems, version 27.0, for year 2009 and version 28.0 for years 2010 and 2011.