Table 1 Characteristics of the study population (n = 1,724,042), comparing patients who did or did not develop postoperative UTI.

Age, years (mean ± SD)*

71.5 ± 8.4

74.8 ± 9.3

< 0.001

Frailty index score

< 0.001

 0

469,709 (27.6%)

4,965 (22.2%)

 1

783,652 (46.1%)

9,813 (43.9%)

 2

381,880 (22.4%)

6,006 (26.9%)

 3

58,447 (3.4%)

1,320 (5.9%)

 4

7,329 (0.4%)

222 (1.0%)

 5

669 (< 0.1%)

30 (0.1%)

Male gender

782,689 (46.0%)

7,977 (35.7%)

< 0.001

Diabetes

377,027 (22.2%)

5,661 (25.3%)

< 0.001

Hypertension

1,133,974 (66.6%)

15,691 (70.2%)

< 0.001

Congestive heart failure

276,062 (16.2%)

5,826 (26.1%)

< 0.001

Chronic obstructive pulmonary disease

131,430 (7.7%)

2,385 (10.7%)

< 0.001

Preoperative anemia

276,062 (16.2%)

5,826 (26.1%)

< 0.001

Disseminated cancer

52,061 (3.1%)

1,267 (5.7%)

< 0.001

Steroid use

79,416 (4.7%)

1,633 (7.3%)

< 0.001

Weight loss: >10% body weight in the past 6 months

30,348 (1.8%)

729 (3.3%)

< 0.001

Transferred from nursing home

31,898 (1.9%)

882 (4.0%)

< 0.001

Impaired preoperative functional status

84,613 (5.0%)

2,414 (10.8%)

< 0.001

Inpatient (vs. outpatient) surgery

1,274,941 (74.9%)

20,364 (91.1%)

< 0.001

Elective (vs. urgent or emergent) surgery

1,277,038 (75.1%)

13,415 (60.0%)

< 0.001

Wound “clean-contaminated” or “contaminated”

523,839 (30.8%)

8,856 (39.6%)

< 0.001