Table 2. Risk Factors for Aseptic and for Septic TKR Revision: Results of Multivariable Cox Proportional Hazards Regression Analysis.
| Variable | Aseptic revision | Septic revision | ||
|---|---|---|---|---|
| HR (95% CI) | P value | HR (95% CI | P value | |
| Age 5 y | 0.78 (0.77-0.79) | <.001 | 0.85 (0.83-0.86) | <.001 |
| Male sex | 1.03 (1.00-1.06) | .046 | 1.61 (1.55-1.68) | <.001 |
| Black race | 1.39 (1.33-1.46) | <.001 | 1.11 (1.03-1.20) | .004 |
| Insurance | ||||
| Medicare | 1 [Reference] | NA | 1 [Reference] | NA |
| Medicaid | 0.94 (0.86-1.03) | .17 | 1.17 (1.04-1.31) | .009 |
| Private | 0.91 (0.88-0.95) | <.001 | 0.76 (0.72-0.80) | <.001 |
| Workers’ compensation | 1.61 (1.51-1.72) | <.001 | 0.95 (0.85-1.06) | .33 |
| Other | 0.92 (0.83-1.01) | .09 | 0.93 (0.81-1.07) | .30 |
| Comorbidities | ||||
| Diabetes | 1.02 (0.98-1.07) | .24 | 1.24 (1.17-1.30) | <.001 |
| Obesity | 0.81 (0.77-0.84) | <.001 | 1.13 (1.07-1.19) | <.001 |
| Kidney disease | 0.86 (0.77-0.95) | .003 | 1.42 (1.29-1.57) | <.001 |
| COPD | 1.05 (0.99-1.10) | .09 | 1.22 (1.15-1.30) | <.001 |
| Inflammatory arthritisa | 0.76 (0.70-0.84) | <.001 | 1.53 (1.39-1.69) | <.001 |
| Surgical complication at index admissionb | 1.15 (0.99-1.34) | .07 | 2.19 (1.87-2.56) | <.001 |
| US Census community variables | ||||
| No college | 0.91 (0.81-1.02) | .11 | 1.14 (0.97-1.35) | .11 |
| Below poverty | 0.98 (0.93-1.03) | .48 | 1.01 (0.94-1.09) | .74 |
| Hospital annual TKR volume | ||||
| ≥645 | 1 [Reference] | NA | 1 [Reference] | NA |
| 236-644 | 1.04 (0.98-1.07) | .23 | 1.13 (1.06-1.21) | <.001 |
| 90-235 | 1.05 (1.00-1.10) | .06 | 1.33 (1.24-1.42) | <.001 |
| ≤89 | 1.14 (1.07-1.22) | <.001 | 1.54 (1.41-1.68) | <.001 |
| Hospital bed capacity | ||||
| ≥400 | 1 [Reference] | NA | 1 [Reference] | NA |
| 200-399 | 1.04 (1.00-1.08) | .07 | 0.99 (0.94-1.05) | .75 |
| 6-199 | 1.03 (0.98-1.08) | .22 | 1.01 (0.94-1.08) | .79 |
| Hospital type | ||||
| Nongovernment (not-for-profit) | 1 [Reference] | NA | 1 [Reference] | NA |
| Government, nonfederal | 1.03 (0.98-1.09) | .21 | 1.08 (1.00-1.16) | .04 |
| Investor-owned (for-profit) | 1.10 (1.05-1.15) | <.001 | 1.12 (1.05-1.20) | <.001 |
| Rural | 0.98 (0.91-1.05) | .51 | 0.86 (0.77-0.96) | .005 |
| Teaching hospital | 0.94 (0.90-0.98) | .001 | 1.14 (1.08-1.20) | <.001 |
| US state | ||||
| New York | 1 [Reference] | NA | 1 [Reference] | NA |
| California | 1.12 (1.08-1.17) | <.001 | 1.16 (1.10-1.23) | <.001 |
| Florida | 1.06 (1.01-1.11) | .009 | 0.92 (0.86-0.98) | .008 |
| Calendar year | 1.02 (1.01-1.03) | <.001 | 1.03 (1.02-1.03) | <.001 |
Abbreviations: COPD, chronic obstructive pulmonary disease; HR, hazard ratio; NA, not applicable; TKR, total knee replacement.
a
Includes rheumatoid arthritis, psoriatic arthritis, and spondyloarthropathy.
b
Includes hemorrhage, wound disruption, and retained foreign body.