Table 4. Variables used in the analysis.
| Variable name | Mean | Standard deviation |
|---|---|---|
| Patient age | 73.56 | 10.94 |
| Sex1 | 1.533 | 0.498 |
| Disabled beneficiary2 | 0.104 | 0.305 |
| Chronic renal disease beneficiary1 | 0.004 | 0.066 |
| PPS exempt unit1 | 0.013 | 0.114 |
| Transferred to another hospital1 | 0.033 | 0.178 |
| Length of stay | 7.633 | 8.57 |
| Intensive care days | 0.625 | 2.59 |
| Coronary care days | 0.250 | 1.44 |
| Number of diagnoses2 | 3.73 | 1.37 |
| Surgery | 0.533 | 0.499 |
| Number of procedures2 | 1.059 | 1.18 |
| DRG weight | 1.248 | 0.807 |
| Craniotomy and spinal procedures (DRGs 1-4)1 | 0.003 | 0.056 |
| Major head and neck procedures (DRG 49)1 | 0.0005 | 0.023 |
| Miscellaneous ear, nose and throat procedures (DRG 55)1 | 0.0009 | 0.030 |
| Cardiovascular procedures (DRGs 103-112, 117, 124, 125)1 | 0.044 | 0.205 |
| Kidney and urinary tract procedures (DRG 315)1 | 0.002 | 0.045 |
| Hysterectomy (DRG 353)1 | 0.0002 | 0.013 |
| Splenectomy and other operation room procedures for blood forming organs (DRGs 392, 393, 394)2 | 0.0004 | 0.020 |
| Neoplasms (DRGs 406, 407, 408)1 | 0.002 | 0.040 |
| Radiotherapy (DRG 409)1 | 0.0008 | 0.029 |
| Chemotherapy (DRG 410)1 | 0.011 | 0.104 |
| Injury procedures (DRG 442)1 | 0.004 | 0.062 |
| Rehabilitation (DRG 462)1 | 0.003 | 0.055 |
1
Coding for dichotomous variables: sex—male = 1, female = 2; disabled beneficiary, chronic renal disease beneficiary, PPS exempt unit, transferred from another hospital—yes = 1, no = 0; specific procedures—procedure performed = 1, procedure not performed = 0.
2
International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM).
NOTE: DRG is diagnosis-related group.
SOURCE: Health Care Financing Administration, Bureau of Data Management and Strategy: Data are from the Medicare Provider Analysis Survey, 1987.