Table 3. Adjusted Incidence Rate Ratios (IRRs) of Prosthetic Joint Infections (PJIs) After Primary Total Knee Arthroplasty (TKA) in the Veterans Affairs Surgical Quality Improvement Project Complete Case Cohort (n = 61 701).
| Characteristic | Adjusted IRR (95% CI)a | ||
|---|---|---|---|
| Early PJI: ≤3 mo | Delayed PJI: >3 and ≤12 mo | Late PJI: >12 mo | |
| No. of PJIs | 513 | 286 | 500 |
| Age, y | |||
| <60 | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| 60-69 | 0.9 (0.7-1.1) | 0.8 (0.6-1.1) | 0.9 (0.7-1.2) |
| ≥70 | 0.8 (0.6-1.0) | 0.8 (0.6-1.2) | 0.6 (0.5-0.9) |
| Urban vs rural center | |||
| Rural | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Urban | 2.3 (1.1-4.9) | 1.3 (0.7-2.6) | 1.6 (0.8-3.3) |
| BMI | |||
| <25.0 | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| 25.0-29.9 | 0.8 (0.6-1.2) | 1.7 (0.9-2.9) | 0.8 (0.6-1.2) |
| 30.0-39.9 | 0.8 (0.6-1.2) | 1.7 (1.0-2.7) | 0.9 (0.7-1.3) |
| ≥40 | 0.9 (0.6-1.4) | 2.7 (1.5-4.9) | 1.3 (0.8-1.9) |
| AUD | |||
| No | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Yes | 1.1 (0.8-1.6) | 2.0 (1.4-2.9) | 1.5 (1.1-2.0) |
| Tobacco use | |||
| Former or never | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Current | 1.3 (1.0-1.6) | 0.9 (0.7-1.2) | 1.0 (0.8-1.3) |
| Heart failure | |||
| No | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Yes | 1.8 (1.3-2.4) | 0.8 (0.5-1.3) | 1.9 (1.3-2.8) |
| Hypertension | |||
| No | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Yes | 1.5 (1.2-2.0) | 1.2 (0.8-1.7) | 1.1 (0.8-1.4) |
| PAD | |||
| No | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Yes | 1.6 (1.1-2.2) | 1.6 (1.0-2.4) | 1.9 (1.3-2.7) |
| HCV infection | |||
| No | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Yes | 1.9 (1.3-2.8) | 1.7 (1.0-2.9) | 2.1 (1.5-3.0) |
| Autoimmune inflammatory arthritis | |||
| No | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Yes | 2.3 (1.5-3.5) | 1.7 (1.0-2.9) | 1.9 (1.2-3.0) |
| Anemia | |||
| No | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Yes | 1.4 (0.9-1.9) | 1.8 (1.3-2.7) | 2.2 (1.5-3.1) |
| Anesthesia type | |||
| Regional | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| General | 1.1 (0.9-1.4) | 1.3 (1.0-1.6) | 1.1 (0.8-1.3) |
| Operative time, h | |||
| <2 | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| ≥2 | 1.3 (1.0-1.6) | 1.3 (1.0-1.7) | 1.1 (0.9-1.4) |
Abbreviations: AUD, alcohol use disorder; BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); HCV, hepatitis C virus; PAD, peripheral artery disease; VA, US Department of Veterans Affairs.
a
The IRR for each variable was adjusted for all other variables as well as by VA center and year of TKA (categorized in 5-year periods from 1999 to 2019).