Table 1. Demographic, Baseline Clinical, and Perioperative Characteristics of the Overall Cohort (n = 79 367).
| Characteristic | Patients, No. (%) | Person-months of follow-up |
|---|---|---|
| Follow-up, median (IQR), mo | 58.0 (22.4-108.2) | 5 647 008 |
| Age, y | ||
| Median (IQR) | 65 (60-71) | NA |
| <60 | 19 682 (24.8) | 1 606 579 |
| 60-69 | 34 632 (43.6) | 2 394 754 |
| ≥70 | 25 053 (31.6) | 1 645 674 |
| Sex | ||
| Female | 4093 (5.2) | 274 224 |
| Male | 75 274 (94.8) | 5 372 783 |
| Race and ethnicitya | ||
| Hispanic | 3484 (4.4) | 243 900 |
| Non-Hispanic Black | 10 642 (13.4) | 734 945 |
| Non-Hispanic White | 58 307 (73.5) | 4 160 585 |
| Otherb | 4181 (5.3) | 328 922 |
| Unknown | 2753 (3.5) | 178 655 |
| Year of TKA | ||
| 1999-2004 | 12 599 (15.9) | 1 503 698 |
| 2005-2009 | 18 767 (23.6) | 1 742 641 |
| 2010-2014 | 23 475 (29.6) | 1 598 900 |
| 2015-2019 | 24 526 (30.9) | 801 767 |
| Urban vs rural center | ||
| Rural | 2551 (3.2) | 205 065 |
| Urban | 76 808 (96.8) | 5 441 347 |
| Missing data | 8 (<0.1) | NA |
| BMI | ||
| <25.0 | 5595 (7.0) | 396 666 |
| 25.0-29.9 | 22 114 (27.9) | 1 591 410 |
| 30.0-39.9 | 43 315 (54.6) | 2 984 255 |
| ≥40 | 5387 (6.8) | 412 417 |
| Missing data | 2956 (3.7) | NA |
| Tobacco use | ||
| Never or former | 56 851 (71.6) | 4 066 693 |
| Current | 21 434 (27.0) | 1 516 583 |
| Missing data | 1082 (1.4) | NA |
| Baseline comorbiditiesc | ||
| AUD | 6436 (8.1) | 409 380 |
| Heart failure | 3839 (4.9) | 220 875 |
| Hypertension | 68 054 (86.0) | 4 767 230 |
| PAD | 3815 (4.8) | 232 108 |
| HIV infection | 133 (0.2) | 9246 |
| HCV infection | 2509 (3.2) | 188 743 |
| HBV infection | 120 (0.2) | 9655 |
| Autoimmune inflammatory arthritis | 2226 (2.8) | 149 622 |
| Anemia | 4009 (5.2) | 247 181 |
| Missing data | 1546 (1.9) | NA |
| Diabetes | 5602 (7.1) | 433 175 |
| CKD | 14 403 (18.4) | 1 018 159 |
| Missing data | 1186 (1.5) | NA |
| Perioperative characteristics obtained from VASQIP cohortd | ||
| Corticosteroids use in prior 30 d | 1114 (1.7) | 72 682 |
| Missing data | 1 (<0.1) | NA |
| ASA score | ||
| 1 | 100 (0.2) | 10 098 |
| 2 | 15 314 (23.5) | 1 244 416 |
| 3 | 48 000 (73.6) | 3 206 147 |
| 4 | 1773 (2.7) | 105 895 |
| Missing data | 1 (<0.1) | NA |
| Anesthesia type | ||
| General | 41 383 (63.5) | 2 980 363 |
| Regionale | 23 805 (36.5) | 1 586 289 |
| Operative time, h | ||
| Median (IQR) | 2.0 (1.7-2.5) | |
| <2 | 31 030 (47.6) | 2 149 297 |
| ≥2 | 34 156 (52.4) | 2 417 239 |
| Missing data | 2 (<0.1) | NA |
| Intraoperative transfusion of packed RBCs | 359 (0.6) | 32 226 |
Abbreviations: ASA, American Society of Anesthesiologists Physical Status Classification System (score range: 1 [indicating a healthy patient] to 4 [indicating a patient with incapacitating severe disease that is a constant threat to life]); AUD, alcohol use disorder; BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; HBV, hepatitis B virus; HCV, hepatitis C virus; ICD-9, International Classification of Diseases, Ninth Revision; ICD-10, International Statistical Classification of Diseases and Related Health Problems, Tenth Revision; NA, not applicable; PAD, peripheral artery disease; RBC, red blood cell; TKA, total knee arthroplasty; VASQIP, Veterans Affairs Surgical Quality Improvement Project.
Race and ethnicity were self-reported.
Included Asian, American Indian or Alaska native, Native Hawaiian or Other Pacific Islander, and multiracial.
Comorbidities of AUD, heart failure, hypertension, diabetes, PAD, HIV infection, HBV infection, and HCV infection were defined by 1 inpatient or 2 outpatient ICD-9 or ICD-10 diagnosis codes. Autoimmune inflammatory arthritis was defined as 1 inpatient or 2 outpatient ICD-9 or ICD-10 diagnosis codes among those with at least 1 outpatient rheumatologic clinic visit during the baseline period. The ICD-9 or ICD-10 diagnosis codes used to identify comorbidities are provided in eTable 2 in Supplement 1. Anemia was defined as hemoglobin level less than 12 g/dL (to convert to grams per liter, multiply by 10.0), and CKD was defined as an eGFR less than 60 mL/min/1.73 m2; eGFR was calculated using the Modified Diet in Renal Disease equation: 175 × (serum creatinine)–1.154 × (age)–0.203 × (0.742, if female) × (1.212, if Black patient).
Perioperative characteristics were available for only a subset of patients in the VASQIP cohort (n = 65 188). Percentages reflect this subset of patients.
Included epidural, spinal, or monitored anesthesia.