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Table 4 Severity-specific algorithms for converting SF-36 data into AQoL scores

From: Can we derive an 'exchange rate' between descriptive and preference-based outcome measures for stroke? Results from the transfer to utility (TTU) technique

Model

Predictor

β

SE

t

Sig.

SF-36 Subscale

     

NIHSS = 0–5

(Constant)

0.0364

0.0423

0.86

0.390

 

Physical Function (PF)

0.0074

0.0014

5.24

0.000

 

Bodily Pain (BP)

0.0006

0.0004

1.81

0.072

 

Social Function (SF)

0.0022

0.0007

3.12

0.002

 

PF*PF

-5.25*10-5

1.22*10-5

-4.29

0.000

 

PF*Mental Health (MH)

2.90*10-5

1.36*10-5

2.13

0.034

 

Vitality (VI)*VI

-1.69*10-5

7.20*10-6

-2.35

0.019

 

VI*Role Physical (RP)

3.79*10-5

9.47*10-6

4.00

0.000

 

General Health (GH)*MH

2.49*10-5

8.61*10-6

2.89

0.004

 

GH*RP

-3.07*10-5

7.89*10-6

-3.89

0.000

 

SF*MH

-1.61*10-5

9.71*10-6

-1.66

0.097

 

0.6346

 

F566,364 = 2.14

0.000

  

Obs = 941

Ids = 567

F10,364 = 22.34

0.000

   

R2 within = 0.38

R2 between = 0.69

R2 overall = 0.67

NIHSS ≥ 6

(Constant)

0.0744

0.0781

0.95

0.343

 

BP*SF

-2.23*10-5

7.60*10-6

-2.93

0.004

 

PF

0.0081

0.0023

3.52

0.001

 

RP

-0.0030

0.0013

-2.29

0.024

 

MH*MH

-2.80*10-5

1.29*10-5

-2.17

0.032

 

VI

-0.0053

0.0031

-1.68

0.096

 

SF*PF

7.89*10-5

2.41*10-5

3.27

0.002

 

PF*PF

-0.0001

1.49*10-5

-8.38

0.000

 

PF*RP

-7.79*10-5

1.86*10-5

-4.20

0.000

 

MH*RP

6.49*10-5

2.82*10-5

2.30

0.000

 

SF*SF

1.84*10-5

6.65*10-6

2.77

0.007

 

VI*MH

8.90*10-5

4.27*10-5

2.09

0.040

 

GH*MH

1.85*10-5

9.26*10-6

1.99

0.049

 

-

-

-

ns

  

Obs = 117

Ids = 96

F12,95 = 35.12

0.000

     

R2 overall = 0.50

SF-36 Item

     

NIHSS = 0–5

(Constant)

-0.2424

0.0757

-3.20

0.001

 

Item 2 (general health change)

-0.0408

0.0153

-2.67

0.008

 

Item 3b (moderate activities)

0.0584

0.0156

3.74

0.000

 

Item 3d (several flights stairs)

0.0321

0.0154

2.09

0.038

 

Item 3h (walking 1/2 km)

0.0384

0.0159

2.42

0.016

 

Item 3j (bathing/dressing)

0.0934

0.0175

5.35

0.000

 

Item 4a (other activities)

0.0590

0.0215

2.74

0.006

 

Item 4b (accomplished less)

-0.0386

0.0220

-1.75

0.080

 

Item 9b (nervous)

0.0195

0.0072

2.70

0.007

 

Item 9f (felt down)

0.0159

0.0085

1.88

0.061

 

Item 9i (tired)

0.0250

0.0069

3.60

0.000

 

Item 10 (social activities, time)

0.0224

0.0068

-3.20

0.001

 

0.6378

 

F567,363 = 2.05

0.000

  

Obs = 942

Ids = 568

F11,363 = 20.68

0.000

   

R2 within = 0.39

R2 between = 0.69

R2 overall = 0.67

NIHSS ≥ 6

(Constant)

0.0331

0.0427

0.77

0.441

 

Item 3a (vigorous activities)

-0.1897

0.0497

-3.82

0.000

 

Item 3b (moderate activities)

-0.2940

0.1393

-2.11

0.037

 

Item 3d (several flights stairs)

0.1462

0.0623

2.35

0.021

 

Item 3g (walking > 1 km)

0.2080

0.0828

2.51

0.014

 

Item 3j (bathing/dressing)

0.0901

0.0251

3.58

0.001

 

Item 6 (social activities, extent)

-0.0139

0.0082

-1.69

0.094

 

Item 9c (down in dumps)

0.0135

0.0068

1.99

0.050

 

Item 11c (expect worse health)

0.0163

0.0066

2.46

0.016

 

-

-

-

ns

  

Obs = 117

Ids = 96

F8,95 = 15.44

0.000

     

R2 overall = 0.37