Table 1.

Baseline Characteristics of the Study Population by Location of Amputation

CharacteristicAll Patients (N=17 463)Foot (n=7343)Below Knee (n=4804)Above Knee (n=5316)P Value*
Age, mean (SD), y73.8 (12.0)73.1 (11.9)71.5 (12.4)76.8 (11.3)<0.001
Age group, n (%)<0.001
 <50772 (4.4)356 (4.8)286 (6.0)130 (2.4)
 50–54569 (3.3)251 (3.4)210 (4.4)108 (2.0)
 55–59854 (4.9)376 (5.1)313 (6.5)165 (3.1)
 60–641108 (6.3)460 (6.3)365 (7.6)283 (5.3)
 65–692131 (12.2)946 (12.9)669 (13.9)516 (9.7)
 70–742880 (16.5)1286 (17.5)818 (17.0)776 (14.6)
 75–793095 (17.7)1328 (18.1)819 (17.0)948 (17.8)
 80–842871 (16.4)1181 (16.1)659 (13.7)1031 (19.4)
 85–892003 (11.5)778 (10.6)443 (9.2)782 (14.7)
 ≥901180 (6.8)381 (5.2)222 (4.6)577 (10.9)
Women, n (%)8570 (49.1)3539 (48.2)2118 (44.1)2913 (54.8)<0.001
Race, no. (%)<0.001
 Black3993 (22.9)1128 (15.4)1227 (25.5)1638 (30.8)
 White12 535 (71.8)5835 (79.5)3289 (68.5)3411 (64.2)
 Other935 (5.4)380 (5.2)288 (6.0)267 (5.0)
Comorbid conditions, n (%)
 Cancer1887 (10.8)827 (11.3)512 (10.7)548 (10.3)0.22
 Cerebrovascular disease5033 (28.8)1790 (24.4)1317 (27.4)1926 (36.2)<0.001
 Chronic obstructive pulmonary disease4920 (28.2)1999 (27.2)1335 (27.8)1586 (29.8)0.004
 Congestive heart failure6184 (35.4)2391 (32.6)1819 (37.9)1974 (37.1)<0.001
 Ischemic heart disease8249 (47.2)3349 (45.6)2390 (49.8)2510 (47.2)<0.001
 Dementia1397 (8.0)360 (4.9)262 (5.5)775 (14.6)<0.001
 Diabetes mellitus10 971 (62.8)4746 (64.6)3308 (68.9)2917 (54.9)<0.001
 Hypertension13 933 (79.8)5841 (79.5)3852 (80.2)4240 (79.8)0.69
 Peripheral arterial disease
  ICD-9-CM or revascularization9447 (54.1)3807 (51.8)2732 (56.9)2908 (54.7)<0.001
  ICD-9-CM only9412 (53.9)3796 (51.7)2718 (56.6)2898 (54.5)<0.001
  Revascularization only924 (5.3)283 (3.9)324 (6.7)317 (6.0)<0.001
 Peripheral vascular disease7706 (44.1)2966 (40.4)2230 (46.4)2510 (47.2)<0.001
 Renal disease4832 (27.7)1906 (26.0)1673 (34.8)1253 (23.6)<0.001
US Census region, n (%)<0.001
 Northeast
  New England763 (4.4)380 (5.2)193 (4.0)190 (3.6)
  Middle Atlantic2310 (13.2)1027 (14.0)574 (11.9)709 (13.3)
 South
  South Atlantic4070 (23.3)1489 (20.3)1162 (24.2)1419 (26.7)
  East South Central1581 (9.1)544 (7.4)410 (8.5)627 (11.8)
  West South Central2389 (13.7)917 (12.5)674 (14.0)798 (15.0)
 Midwest
  East North Central2971 (17.0)1347 (18.3)825 (17.2)799 (15.0)
  West North Central1221 (7.0)628 (8.6)302 (6.3)291 (5.5)
 West
  Mountain684 (3.9)356 (4.8)213 (4.4)115 (2.2)
  Pacific1474 (8.4)655 (8.9)451 (9.4)368 (6.9)
 Rural location, n (%)5092 (29.2)2065 (28.1)1392 (29.0)1635 (30.8)0.005
 Outpatient evaluation and management visit, n (%)5477 (31.4)2437 (33.2)1627 (33.9)1413 (26.6)<0.001
  Cardiologist4649 (26.6)2138 (29.1)1382 (28.8)1129 (21.2)<0.001
  Interventional radiologist20 (0.1)0.90
  Peripheral vascular disease specialist69 (0.4)26 (0.4)21 (0.4)22 (0.4)0.75
  Vascular surgeon1421 (8.1)549 (7.5)437 (9.1)435 (8.2)0.006
Year of index amputation, n (%)<0.001
  20022323 (13.3)824 (11.2)693 (14.4)806 (15.2)
  20032217 (12.7)848 (11.5)658 (13.7)711 (13.4)
  20042130 (12.2)836 (11.4)633 (13.2)661 (12.4)
  20052042 (11.7)812 (11.1)582 (12.1)648 (12.2)
  20061789 (10.2)752 (10.2)493 (10.3)544 (10.2)
  20071713 (9.8)746 (10.2)436 (9.1)531 (10.0)
  20081765 (10.1)833 (11.3)437 (9.1)495 (9.3)
  20091776 (10.2)826 (11.2)437 (9.1)513 (9.7)
  20101708 (9.8)866 (11.8)435 (9.1)407 (7.7)
  • ICD-9-CM indicates International Classification of Diseases, Ninth Revision, Clinical Modification.

  • * We tested for differences by location (foot, below the knee, or above the knee) using χ2 tests for categorical variables and Kruskal–Wallis tests for continuous variables.

  • Data not shown for cells with <11 observations.