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Table 4 Statistical models for adjusted per-infusion total (administration and drug) costs (€2011)

From: Administration costs of intravenous biologic drugs for rheumatoid arthritis

Parametera

OLS (full)

OLS (sign.)

LN-OLS (full)

LN-OLS (sign.)

GLM (full)b

GLM (sign.)b

 

Coef. 95% CI

Coef. 95% CI

Coef. 95% CI

Coef. 95% CI

Coef. 95% CI

Coef. 95% CI

University hospital

5.35

NR

0.0243

NR

0.0100

NR

-537.73–548.42

-0.2525–0.3011

-0.1683–0.1882

District hospitalc

155.44

NR

0.1171

NR

0.0614

NR

-277.97–588.84

-0.0767–0.3109

-0.0774–0.2003

Rituximab

807.61***

773.22***

0.2943*

0.2815*

0.3502***

0.3340***

434.58–1180.64

398.34–1148.10

0.0545–0.5339

0.0492–0.5139

0.1974–0.5030

0.1834–0.4847

Abataceptd

-619.85

-713.33

-0.1826

-0.2440

-0.2158

-0.2553

-1836.24–596.54

-1920.71–494.05

-0.6012–0.2360

-0.6516–0.1635

-0.5026–0.0710

-0.5337–0.0231

Tocilizumabd

70.29

9.43

0.0897

0.0548

0.0248

-0.0034

-332.87–473.44

-395.93–414.79

-0.1444–0.3238

-0.1630–0.2715

-0.1447–0.1942

-0.1622–0.1553

Pool of bDMARDs

359.77

NR

0.1167

NR

0.1603

NR

-747.32–1466.86

-0.2955–0.5290

-0.1443–0.4650

Low dose

-1449.67***

-1477.90***

-0.7999***

-0.8005***

-0.7217***

-0.7325***

-1776.25–-1123.09

-1799.91–-1155.89

-1.0147–-0.5852

-1.0041–-0.5968

-0.8763–-0.5671

-0.8823–-0.5828

High dose

2000.45***

1979.89***

0.5459***

0.5586***

0.5873***

0.5762***

1415.46–2585.45

1453.46–2506.33

0.3814–0.7104

0.4225–0.6947

0.4546–0.7200

0.4546–0.6979

Constant

2511.29***

2626.89***

7.7763***

7.8403***

7.7980***

7.8491***

2232.45–2790.13

2416.33–2837.45

7.6524–7.9000

7.7534–7.9273

7.7070–7.8891

7.7716–7.9266

Tests

      

N

86

86

86

86

86

86

R2

0.76

0.76

0.71

0.71

NR

NR

Prob

0.00***

0.00***

0.00***

0.00***

NR

NR

LL

-688.32

-689.07

-25.83

-26.91

-758.35

-758.42

AIC

1394.65

1390.14

69.66

65.81

1534.70

1528.84

BIC

1416.74

1404.86

91.75

80.54

1556.78

1543.56

  1. OLS = ordinary least squares regression model. Sign. = significant model. LN-OLS = OLS regression model with logarithmic transformation in dependent parameter. GLM = generalized linear model regression. Coef. = coefficient. 95%CI = 95% confidence interval. * p-value < 0.050. ** p-value < 0.010. *** p-value < 0.001. NR = not reported. bDMARD = biologic antirheumatic drug. N = number of observations. R2 = coefficient of determination. Prob = model p-value. LL = log likelihood. AIC = Akaike information criteria. BIC = Bayesian information criteria. a Contrast is central district hospital, infliximab and indicated common adult rheumatoid arthritis dose. b Gamma distribution and log link function in GLM provided the best fit among GLMs. c Few costs were obtained from (non-university or non-central) district hospitals. d Can be biased upwards due to low number of observations.