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Table 1 Patient demographics and hospital characteristics
| Total sample (N= 7183) | MRSA (N = 2387) | Non- MRSA (N = 4796) | P-Value | |
|---|---|---|---|---|
| Frequency (%) | Frequency (%) | Frequency (%) | ||
| Age in years, mean (SD) | 56.5 (19.4) | 51.5 (19.6) | 59.0 (18.8) | <0.001 |
| 18-44 | 2066 (28.8%) | 956 (40.1%) | 1110 (23.1%) | |
| 45-54 | 1285 (17.9%) | 463 (19.4%) | 822 (17.1%) | |
| 55-64 | 1275 (17.8%) | 335 (14%) | 940 (19.6%) | |
| 65-74 | 971 (13.5%) | 229 (9.6%) | 742 (15.5%) | |
| 75-84 | 947 (13.2%) | 258 (10.8%) | 689 (14.4%) | |
| >85 | 639 (8.9%) | 146 (6.1%) | 493 (10.3%) | |
| Gender | ||||
| Male | 3966 (55.2%) | 1364 (57.1%) | 2602 (54.3%) | 0.013 |
| Female | 3216 (44.8%) | 1022 (42.8%) | 2194 (45.7%) | |
| Unknown | 1 (0%) | 1 (0%) | 0 (0%) | |
| Race | ||||
| Caucasian | 5314 (74%) | 1709 (71.6%) | 3605 (75.2%) | <0.001 |
| African American | 1507 (21%) | 572 (24%) | 935 (19.5%) | |
| Other/Unknown | 362 (5%) | 106 (4.4%) | 256 (5.3%) | |
| Insurance type | ||||
| Commercial | 963 (13.4%) | 331 (13.9%) | 632 (13.2%) | <0.001 |
| Medicare | 1741 (24.2%) | 444 (18.6%) | 1297 (27.0%) | |
| Medicaid | 456 (6.3%) | 161 (6.7%) | 295 (6.2%) | |
| Self-paid | 203 (2.8%) | 86 (3.6%) | 117 (2.4%) | |
| Other/Unknown | 3820 (53.2%) | 1365 (57.2%) | 2455 (51.2%) | |
| Patient type | ||||
| Surgical | 1983 (27.6%) | 613 (25.7%) | 1370 (28.6%) | 0.010 |
| Medical | 5200 (72.4%) | 1774 (74.3%) | 3426 (71.4%) | |
| Year of discharge | ||||
| 2005 | 875 (12.2%) | 265 (11.1%) | 610 (12.7%) | 0.380 |
| 2006 | 1648 (22.9%) | 552 (23.1%) | 1096 (22.9%) | |
| 2007 | 1935 (26.9%) | 660 (27.6%) | 1275 (26.6%) | |
| 2008 | 2250 (31.3%) | 750 (31.4%) | 1500 (31.3%) | |
| 2009 | 475 (6.6%) | 160 (6.7%) | 315 (6.6%) | |
| Hospital Characteristics | ||||
| Census region | ||||
| Northeast | 2887 (40.2%) | 818 (34.3%) | 2069 (43.1%) | <0.001 |
| Midwest | 1897 (26.4%) | 573 (24.0%) | 1324 (27.6%) | |
| South | 2123 (29.6%) | 923 (38.7%) | 1200 (25%) | |
| West | 276 (3.8%) | 73 (3.1%) | 203 (4.2%) | |
| Urban setting (vs. rural) | 7171 (99.8%) | 2385 (99.9%) | 4786 (99.8%) | 0.358 |
| Hospital bed size | ||||
| 6-99 | 371 (5.2%) | 166 (7.0%) | 205 (4.3%) | <0.001 |
| 100-199 | 980 (13.6%) | 316 (13.2%) | 664 (13.8%) | |
| 200-299 | 1751 (24.4%) | 557 (23.3%) | 1194 (24.9%) | |
| 300-499 | 2116 (29.5%) | 663 (27.8%) | 1302 (27.1%) | |
| ≥500 | 1965 (27.4%) | 685 (28.7%) | 1431 (29.8%) | |
| Teaching (vs. non-teaching) | 4412 (61.4%) | 1406 (58.9%) | 3006 (62.7%) | 0.002 |
| Charlson comorbidity index, mean (SD) | 1.8 (2.1) | 1.5 (2.0) | 2.0 (2.1) | <0.001 |
| Risk factors for healthcare-associated infection (any) | 2543 (35.4%) | 777 (32.6%) | 1766 (36.8%) | <0.001 |
| Recent hospital discharge (within 180 days) or recent outpatient surgery | 2,255 (31.4%) | 702 (29.4%) | 1,553 (32.8%) | 0.011 |
| Outpatient hemodialysis within 90 days or ESRD patient | 591 (8.2%) | 176 (7.4%) | 415 (8.7%) | 0.063 |
| Admission from a chronic care facility | 369 (5.1%) | 105 (4.4%) | 264 (5.5%) | 0.046 |
| Mechanical ventilation/Dependence on respirator | 48 (0.7%) | 12 (0.5%) | 36 (0.8%) | 0.224 |
| Immunosuppression Factors (any below), N (%) | 1931 (26.9%) | 546 (22.9%) | 1385 (28.9%) | <0.001 |
| ESRD (current or prior) | 868 (12.1%) | 247 (10.3%) | 621 (12.9%) | 0.001 |
| Received systemic corticosteroid/immunosuppressive/chemotherapy | 590 (8.2%) | 177 (7.4%) | 413 (8.6%) | 0.082 |
| Leukemia, lymphoma, metastasis | 388 (5.4%) | 80 (3.4%) | 308 (6.4%) | <0.001 |
| Autoimmune diseases* | 266 (3.7%) | 75 (3.1%) | 191 (4%) | 0.076 |
| Aplastic anemia and pancytopenia | 144 (2.0%) | 22 (0.9%) | 122 (2.5%) | <0.001 |
| Organ transplantation | 116 (1.6%) | 32 (1.3%) | 84 (1.8%) | 0.193 |
| HIV/AIDS | 55 (0.8%) | 31 (1.3%) | 24 (0.5%) | <0.001 |
| Neutropenia | 46 (0.6%) | 6 (0.3%) | 40 (0.8%) | 0.004 |
| Other immunosuppression factors** | 17 (0.2%) | 4 (0.2%) | 13 (0.3%) | 0.395 |
| Comorbidity (current or 12 months prior to admission unless noted), N (%) | ||||
| Hypertension | 3585 (49.9%) | 1071 (44.9%) | 2514 (52.4%) | <0.001 |
| Diabetes mellitus by diagnosis code or medications | 3440 (47.9%) | 936 (39.2%) | 2504 (52.2%) | <0.001 |
| Diabetic lower extremity infection (current encounter) | 1746 (24.3%) | 458 (19.2%) | 1288 (26.9%) | <0.001 |
| Renal dysfunction at baseline | 1348 (18.8%) | 332 (13.9%) | 1016 (21.2%) | <0.001 |
| Heart failure | 1221 (17.0%) | 330 (13.8%) | 891 (18.6%) | <0.001 |
| Coronary artery disease | 1139 (15.9%) | 328 (13.7%) | 811 (16.9%) | 0.001 |
| Complication of electronic internal device (ICD-9 Code = 996.6, current encounter) | 1087 (15.1%) | 259 (10.9%) | 828 (17.3%) | <0.001 |
| Chronic obstructive pulmonary disease | 815 (11.3%) | 250 (10.5%) | 565 (11.8%) | 0.100 |
| Cardiac dysrhythmias (prior to index encounter) | 569 (7.9%) | 166 (7%) | 403 (8.4%) | 0.032 |
| Acute coronary syndrome/angina | 534 (7.4%) | 144 (6%) | 390 (8.1%) | 0.001 |
| Cancer | 521 (7.3) | 110 (4.6%) | 411 (8.6%) | <0.001 |
| Cerebrovascular disease | 283 (3.9%) | 81 (3.4%) | 202 (4.2%) | 0.093 |
| Hematologic dysfunction at baseline | 265 (3.7%) | 87 (3.6%) | 215 (4.5%) | 0.096 |
| Cirrhosis/chronic liver disease | 198 (2.8%) | 45 (1.9%) | 153 (3.2%) | 0.001 |
| Laboratory values, mean (SD) | ||||
| Hematocrit (%) | 36.7 (6.0) | 37.4 (5.7) | 36.4 (6.1) | <0.001 |
| White blood cell count (k/mm3) | 12.8 (8.4) | 12.5 (8.3) | 12.9 (8.4) | 0.048 |
| Serum creatinine (mg/dL) | 2.0 (2.3) | 1.7 (2.1) | 2.1 (2.4) | <0.001 |
| Platelet count (k/mm3) | 266.8 (119.2) | 272.2 (109.3) | 264.1 (123.7) | 0.015 |
