Table 2.
Univariate Analysis for predictors of length of stay following total hip and total knee arthroplasty in patients with rheumatoid arthritis.
| Univariate variable | Level | Estimated model coefficient (standard error) |
Percentage change in the original scale of length
of stay with 1 unit increase of a continuous predictor, or a
comparison of one category to the reference category for a
categorical predictor* (95% CI) |
P value |
|---|---|---|---|---|
| Age | 0.002 (0.002) | 0.2% (−0.19%, 0.59%) | .47 | |
| Sex | Female vs. Male | 0.22 (0.07) |
24.61% (8.63%, 42.93%) | .001 |
| Race | Asian vs White | −0.10 (0.17) |
−9.51% (−35.16%, 26.26%) | .56 |
| Black vs. White | 0.11 (0.09) | 11.63% (−6.42%, 33.16%) | .19 | |
| Other vs. White | −0.03 (0.08) | −2.96% (−17.03%, 13.52%) | .75 | |
| Ethnicity | Hispanic or Latino vs Not Hispanic nor Latino | 0.06 (0.10) | 6.18% (−12.72%, 29.18%) | .55 |
| BMI | 0.008 (0.004) |
0.8% (0.02%, 1.60%) | .03 | |
| Have you ever smoked cigarettes | No vs. Yes | 0.03 (0.05) | 3.05% (−6.58%, 13.66%) | .56 |
| Highest level of education completed | College or above vs. Less than college | −0.02 (0.08) | −1.98% (−16.21%, 14.66%) | .74 |
| Employment status | Employed vs. Unemployed or Disabled or Retired | −0.11 (0.05) | −10.42% (−18.77%, −1.19%) | .04 |
| Other vs. Unemployed or Disabled or Retired | 0.08 (0.13) | 8.33% (−16.04%, 39.77%) | .53 | |
| RA Criteria | criteria 1987 vs Meets BOTH criteria | −0.02 (0.09) | −1.98% (−17.83%, 16.93%) | .83 |
| criteria 2010 vs Meets BOTH criteria | −0.02 (0.07) | −1.98% (−14.55%, 12.43%) | .79 | |
| TXA | No vs. Yes | −0.014 (0.06) |
−1.39% (−12.33%, 10.92%) | .81 |
| Type of Surgery | Hip vs. Knee | −0.22 (0.05) |
−19.75% (−27.24%, −11.49%) | .0001 |
| NSAIDs | No vs. Yes | 0.09 (0.05) | 9.42% (−0.79%, 20.68%) | .10 |
| Opioid | No vs. Yes | −0.19 (0.05) | −17.3% (−25.02%, −8.79%) | .001 |
| Methotrexate | No vs. Yes | 0.09 (0.05) | 9.42% (−0.80%, 20.68%) | .10 |
| Steroids | No vs. Yes | −0.09 (0.06) | −8.60% (−18.74%, 2.80%) | .09 |
| Biologic | No vs. Yes | −0.002 (0.05) | −0.20% (−9.52%, 10.08%) | .96 |
| Other DMARD | No vs. Yes | 0.01 (0.06) | 1.01% (−10.20%, 13.61%) | .85 |
| Prior Transfusion | No vs. Yes | 0.004 (0.14) | 0.40% (−23.69%, 32.10%) | .98 |
| Postoperative Transfusion | No vs. Yes | −0.24 (0.08) | −21.34% (−32.75%, −7.98%) | .01 |
| Prior DVT | No vs. Yes | −0.23 (0.13) | −20.54% (−38.42%, 2.51%) | .06 |
| History of PE | No vs. Yes | −0.24 (0.21) | −21.33% (−47.88%, 18.72%) | .25 |
| History of CVA | No vs. Yes | 0.10 (0.13) | 10.52% (−14.34%, 42.59%) | .46 |
| History of Stroke | No vs. Yes | 0.14 (0.16) | 15.03% (−15.94%, 57.40%) | .37 |
| History of Malignancy | No vs. Yes | −0.05 (0.09) | −4.88% (−20.26%, 13.47%) | .59 |
| History of Hormone Therapy | No vs. Yes | −0.07 (0.10) |
−6.76% (−23.36%, 13.43%) | .49 |
| History of Myocardial Infraction | No vs. Yes | −0.18 (0.29) | −16.47% (−52.59%, 47.46%) | .53 |
| Hemoglobin at baseline | −0.03 (0.02) | −2.96% (−6.69%, 0.92%) | .11 | |
| Platelet count | 0.0002 (0.0003) |
0.02% (−0.04%, 0.08%) | .51 | |
| Estimated blood loss | 0.0004 (0.0004) |
0.04% (−0.04%, 0.12%) | .42 | |
| 0.0007 (0.0005) |
0.07% (−0.03%, 0.17%) | .19 | ||
| −0.0002 (0.0002) | −0.02% (−0.06%, 0.02%) | .44 | ||
| Duration of Surgery | 0.003 (0.001) |
0.30% (0.10%, 0.50%) | .01 | |
| HOOs/KOOS pain at baseline | −0.003 (0.001) | −0.30% (−0.49%, −0.10%) | .02 | |
| HOOs/KOOS function at baseline | −0.004 (0.001) |
−0.40% (−0.59%, −0.20%) | .003 | |
| Duration of disease | 0.005 (0.002) | 0.5% (0.11%, 0.90%) | .03 | |
| MD−Haq at baseline | 0.04 (0.02) | 4.08% (0.08%, 8.24%) | .01 | |
| DAS28_esr at baseline | 0.05 (0.02) | 5.13% (1.09%, 9.33%) | .02 | |
| CDAI at baseline | 0.004 (0.003) | 0.4% (−0.19%, 0.99%) | .11 | |
| CRP result at baseline | −0.007 (0.01) |
−0.70% (−2.62%, 1.27%) | .58 | |
| ESR result at baseline | 0.003 (0.001) | 0.3% (0.1%, 0.50%) | .03 | |
| 0.0001 (0.0001) |
0.01% (−0.01%, 0.03%) | .34 | ||
| 0.0001 (0.0001) |
0.01% (−0.01%, 0.03%) | .20 |
CI confidence interval, BMI body mass index, RA rheumatoid arthritis, TKA total knee arthroplasty, TXA tranexamic acid, DMARD disease modifying anti-rheumatic drugs, DVT deep vein thrombosis, PE pulmonary embolus, CVA cerebrovascular accident, CDAI Clinical Disease Activity Index, CRP C-reactive protein, ESR erythrocyte sedimentation rate.
*
Percentage change in the original scale of length of stay with 1 unit increase of a continuous predictor, or a comparison of one category to the reference category for a categorical predictor: (exponential [estimated model coefficient]-1)*100. Multivariate analysis included all characteristics found significant in the univariate analysis.