Table 2.
Characteristics of patients in the study hospitals (N = 76,036).
| Variable | n (%) | |
|---|---|---|
| Age (in years): mean (SD) | 54.99 | (15.66) |
| Male | 38,072 | (50.1) |
| Transfer a | 2,422 | (3.4) |
| Emergency admission a | 16,321 | (22.6) |
| Major Diagnostic Categories (MDCs) | ||
| General surgery | ||
| Diseases and disorders of the digestive system (MDC 6) | 10,962 | (14.4) |
| Diseases and disorders of the hepatobiliary system (MDC 7) | 13,539 | (17.8) |
| Diseases and disorders of the skin, subcutaneous tissue, or breast (MDC 9) | 8,475 | (11.2) |
| Endocrine, nutritional, or metabolic diseases and disorders (MDC 10) | 7,016 | (9.2) |
| Orthopedic surgery | ||
| Diseases and disorders of the musculoskeletal system (MDC 8) | 21,362 | (28.1) |
| Vascular surgery | ||
| Diseases and disorders of the circulatory system (MDC 5) | 14,682 | (19.3) |
| Comorbiditiesb | ||
| Congestive heart failure | 1,053 | (1.4) |
| Arrhythmia | 4,009 | (5.3) |
| Aortic stenosis | 826 | (1.1) |
| Pulmonary circulation disorders | 249 | (0.3) |
| Peripheral vascular disorders | 939 | (1.2) |
| Hypertension | 17,813 | (23.4) |
| Paralysis | 275 | (0.4) |
| Neurodegenerative disorders | 419 | (0.6) |
| Chronic obstructive pulmonary disease | 3,700 | (4.9) |
| Diabetes mellitus | 11,518 | (15.2) |
| Hypothyroidism | 1,280 | (1.7) |
| Renal failure | 805 | (1.1) |
| Liver disease | 6,822 | (9.0) |
| Peptic ulcer disease, no bleeding | 4,411 | (5.8) |
| Cancer | 5,586 | (7.4) |
| Rheumatoid arthritis/collagen vascular diseases | 200 | (0.3) |
| Coagulopathy | 1,800 | (2.4) |
| Weight loss | 3,105 | (4.1) |
| Fluid and electrolyte disorders | 1,481 | (1.9) |
| Deficiency anemia | 1,786 | (2.3) |
| Alcohol abuse | 258 | (0.3) |
| Psychoses | 179 | (0.2) |
| Depression | 543 | (0.7) |
| Death within 30 days of admission | 514 | (0.7) |
Notes: M = mean; SD = standard deviation; n = number; MDC = major diagnostic category.
a
Information was missing on transfer or emergency admission status for 3,751 of the 76,036 patients (4.9%).
b
The comorbidities listed are from Elixhauser (1998). We excluded, in the table and in our analyses, HIV/AIDS, obesity, blood loss anemia, and drug abuse, which were extremely uncommon (n < 10 in all cases), and we combined Elixhauser’s three cancer types (lymphoma, metastatic cancer, and solid tumors without metastisis).