Table 1

Demographic and other cohort characteristics

Entire cohort
N=8,127,182*
No gout
N=7,895,812*
Gout
N=2 31 470*
  N (%), unless specified otherwise
Age, mean (SE); median66.4 (0.03); 66.566.5 (0.02); 66.568.1 (0.05); 68.0
 Age category
  <50430 140 (5.3%)423 713 (5.4%)6427 (2.8%)
  50–642 872 619 (35.3%)2 800 798 (35.5%)71 821 (31.0%)
  65–793 969 942 (48.8%)3 842 081 (48.7%)127 861 (55.2%)
  ≥80850 132 (10.5%)824 780 (10.4%)25 352 (11.0%)
 Gender
  Female5 126 808 (63.1%)5 050 791 (64.0%)76 017 (32.8%)
  Male2 985 796 (36.7%)2 830 384 (35.8%)155 412 (67.1%)
 Race
  White5 507 281 (67.8%)5 346 818 (67.7%)160 463 (69.3%)
  Black472 392 (5.8%)453 237 (5.7%)19 155 (8.3%)
  Hispanic340 292 (4.2%)333 934 (4.2%)6358 (2.7%)
  Other/missing1 807 102 (22.2%)1 761 613 (22.3%)45 489 (19.7%)
 Primary diagnosis
  Rheumatoid arthritis64 126 (0.8%)63 330 (0.8%)796 (0.3%)
  Aseptic bone necrosis21 031 (0.3%)20 698 (0.3%)333 (0.1%)
  Osteoarthritis7 866 436 (96.8%)7 640 179 (96.8%)226 257 (97.7%)
  Other173 672 (2.1%)169 632 (2.1%)4040 (1.7%)
  Fracture1904 (0.0%)1865 (0.0%)39 (0.0%)
 Hospital location/teaching
  Rural1 041 160 (12.8%)1 012 017 (12.8%)29 143 (12.6%)
  Urban3 665 765 (45.1%)3 564 877 (45.1%)100 888 (43.6%)
  Urban teaching3 398 113 (41.8%)3 297 365 (41.8%)100 748 (43.5%)
 Insurance
  Medicaid226 917 (2.8%)222 499 (2.8%)4418 (1.9%)
  Medicare4 631 192 (57.0%)4 485 862 (56.8%)145 330 (62.8%)
  Other267 624 (3.3%)261 284 (3.3%)6340 (2.7%)
  Private2 947 675 (36.3%)2 873 513 (36.4%)74 162 (32.0%)
  Self36 588 (0.5%)35 831 (0.5%)757 (0.3%)
 Income category
  0-25th percentile1 511 692 (18.6%)1 464 907 (18.6%)46 785 (20.2%)
  25-50th percentile2 156 223 (26.5%)2 094 636 (26.5%)61 587 (26.6%)
  50-75th percentile2 158 011 (26.6%)2 097 245 (26.6%)60 766 (26.3%)
  75-100th percentile2 151 430 (26.5%)2 093 366 (26.5%)58 064 (25.1%)
 Hospital bed size
  Small1 408 128 (17.3%)1 366 931 (17.3%)41 197 (17.8%)
  Medium2 107 250 (25.9%)2 047 151 (25.9%)60 099 (26.0%)
  Large4 589 661 (56.5%)4 460 177 (56.5%)129 484 (55.9%)
 Hospital region
  Northeast1 359 230 (16.7%)1 321 311 (16.7%)37 919 (16.4%)
  Midwest2 269 799 (27.9%)2 207 287 (28.0%)62 512 (27.0%)
  South2 957 629 (36.4%)2 869 525 (36.3%)88 104 (38.1%)
  West1 540 624 (19.0%)1 497 690 (19.0%)42 934 (18.5%)
 Deyo-Charlson Score
  04 104 090 (50.5%)4 019 384 (50.9%)84 706 (36.6%)
  12 064 888 (25.4%)2 005 515 (25.4%)59 373 (25.7%)
  ≥21 958 304 (24.1%)1 870 913 (23.7%)87 391 (37.8%)
 Gout231 470 (2.8%)231 470 (100.0%)
In-hospital post-TKA complications
 Transfusion1 288 544 (15.9%)1 251 071 (15.8%)37 473 (16.2%)
 Revision15 310 (0.2%)14 843 (0.2%)467 (0.2%)
 Infection8165 (0.1%)7938 (0.1%)227 (0.1%)
 Died during hospitalisation7875 (0.1%)7709 (0.1%)166 (0.1%)
Post-TKA healthcare utilisation
 Length of stay, mean (SE); median3.53 (0.01); 2.703.54 (0.01); 2.703.59 (0.01); 2.69
 Length of stay category
  ≤35 218 769 (64.2%)5 068 813 (64.2%)149 956 (64.8%)
  >32 908 513 (35.8%)2 826 999 (35.8%)81 514 (35.2%)
 Discharge status
  Home4 965 279 (61.1%)4 827 422 (61.1%)137 857 (59.6%)
  Rehabilitation facility†3 130 289 (38.5%)3 037 405 (38.5%)92 884 (40.1%)
  • *U.S. National estimates were based on the following in the 20% NIS sample: All, N=1,690,531; No gout, N=1,642,585; gout, N=47 946.

  • †Rehabilitation facility included short- or long-term care hospital, skilled nursing facility (SNF), intermediate care facility, or a certified nursing facility.

  • LOS, length of stay; TKA, total knee arthroplasty.