Skip to main content

Table 2 Random forests performance measures in the development and validation data across all outcomes

From: Predicting patient-reported outcomes following lumbar spine surgery: development and external validation of multivariable prediction models

 

Classification outcomes

Regression outcomes

 

COMI MCID

Back pain MCID

Leg pain MCID

COMI change

Back pain change

Leg pain change

Development

 AUC (95% CI)

0.62 (0.60, 0.64)

0.66 (0.64, 0.68)

0.67 (0.64, 0.69)

   

 Sensitivity / Specificity (optimal cut-off)

0.51 / 0.68 (0.58)

0.67 / 0.56 (0.53)

0.71 / 0.53 (0.67)

   

 OOB error / RMSE

39.84%

38.72%

29.77%

2.89

2.94

3.33

 pseudo-R2

   

0.112

0.207

0.186

 Calibration intercept (95% CI)

0.11 (0.04, 0.18)

0.01 (-0.08, 0.10)

0.01 (-0.12, 0.14)

0.04 (-0.46, 0.54)

-0.06 (-0.33, 0.22)

-0.18 (-0.64, 0.28)

 Calibration slope (95% CI)

0.83 (0.71, 0.95)

1.00 (0.83, 1.16)

0.95 (0.76, 1.13)

0.98 (0.84, 1.13)

1.02 (0.92, 1.13)

1.05 (0.93, 1.17)

 Calibration-in-the-large

0.01

 < 0.01

-0.03

-0.02

-0.01

 < 0.01

 E/O

0.98

0.99

1.04

   

 Brier score

0.23

0.22

0.20

   

 ECI

0.07

0.09

0.16

   

 Pearson's r (observed vs. predicted)

   

0.33

0.45

0.43

Validation

 AUC (95% CI)

0.62 (0.60, 0.65)

0.68 (0.66, 0.71)

0.66 (0.63, 0.69)

   

 Sensitivity / Specificity (optimal cut-off)

0.56 / 0.64 (0.56)

0.86 / 0.39 (0.47)

0.75 / 0.50 (0.66)

   

 RMSE

   

2.94

3.04

3.33

 pseudo-R2

   

0.152

0.252

0.220

 Calibration intercept (95% CI)

0.06 (-0.07, 0.18)

-0.06 (-0.17, 0.06)

0.01 (-0.16, 0.19)

-0.26 (-0.96, 0.45)

-0.04 (-0.42, 0.35)

-0.25 (-0.72, 0.22)

 Calibration slope (95% CI)

0.94 (0.71, 1.16)

1.20 (0.99, 1.41)

0.96 (0.72, 1.21)

1.12 (0.91, 1.33)

1.14 (1.00, 1.29)

1.14 (1.02, 1.25)

 Calibration-in-the-large

0.02

0.05

-0.01

0.14

0.28

0.25

 E/O

0.96

0.92

1.02

   

 Brier score

0.23

0.22

0.20

   

 ECI

0.07

0.38

0.17

   

 Pearson's r (observed vs. predicted)

   

0.39

0.5

0.47

  1. AUC Area Under the Receiver-Operating Characteristic Curve, CI Confidence interval, E/O Expected-to-observed events ratio, ECI Estimated calibration index, MCID Minimal Clinically Important Difference, OOB error Out-of-bag misclassification rate, RMSE Root mean square error