Table 3.
A. Three variable model for predicting graft failure in BKVN patientsa.
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Variable | Coefficient | Odds Ratio (95% Confidence Intervals) | P Value |
Constant | −10.59 | ||
Urinary cell PAI-1 mRNA | 1.01 | 2.8 (1.12 – 6.78) | 0.03 |
Serum Creatinine | 0.59 | 1.8 (0.55 – 6.02) | 0.33 |
Biopsy B/C | 1.65 | 5.2 (0.38 – 70.38) | 0.22 |
| |||
Model pseudo-R2 valueb: 0.4142, P=0.0015. | |||
Composite Score Equation: −10.59 + 1.01Ln(PAI-1/18S) + 0.59(serum creatinine mg/dL) + 1.65(biopsy BKVN stage B/C[1] or A[0]). |
B. Two variable model for predicting graft failure in BKVN patientsc.
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Variable | Coefficient | Odds Ratio (95% Confidence Interval) | P value |
Constant | −10.61 | ||
Urinary cell PAI-1 mRNA | 1.14 | 3.1 (1.28 – 7.54) | 0.01 |
Serum Creatinine | 0.72 | 2.1 (0.63 – 6.77) | 0.23 |
| |||
Model pseudo-R2 valueb: 0.3682, P=0.001. | |||
Composite Score Equation: −10.61 + 1.14Ln(PAI-1/18S) + 0.72(serum creatinine mg/dL). |
Multivariable logistic regression models were constructed including variables associated (P<0.1) with graft failure by bivariate analysis (SDC Table S2). Since Spearman’s rank-order correlation analysis showed that the mRNAs are highly related with each other (SDC, Table S4), only one mRNA measure was added to each logistic model that included serum creatinine level and BKVN biopsy stage. Among the 7 models created with the addition of different mRNAs to serum creatinine and biopsy stage (SDC Table S5), the combination of creatinine, biopsy stage and PAI-1mRNA was the best predictor. The coefficient, odds ratio and the P value for each variable included in this optimum model are provided in Table 3A.
R2 value indicates the percent of variation in the dependent variable (graft failure) that can be explained by the predictor variables (e.g., PAI-mRNA level) in the model. It ranges from 0 to 1.0 with a value of 1.0 indicating the perfect predictor. The equivalent terminology for the term R2 used in the linear regression model is pseudo-R2 in the logistic regression model;
Table 3B shows the coefficient, odd ratios and P values for the noninvasive prediction model comprised of serum creatinine level and urinary cell PAI-1 mRNA level and without the biopsy results. None of the other mRNAs included in the prediction models shown in SDC Table S5 was an independent predictor (P<0.05) in the multivariable logistic regression analysis.