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Table 1 Patient demographics and hospital characteristics

From: Development and validation of a bedside risk score for MRSA among patients hospitalized with complicated skin and skin structure infections

  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
  1. * Rheumatoid arthritis, multiple sclerosis, psoriasis, Crohn's disease.
  2. ** Includes cystic fibrosis, bone marrow transplant, pulmonary tuberculosis, abnormalities of spleen.
  3. Abbreviations: ESRD, end-stage renal disease; HIV/AIDS, human immunodeficiency virus/acquired immune deficiency syndrome; ICD-9, International Classification of Disease; MRSA, methicillin-resistant Staphylococcus aureus; SD, standard deviation.