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Table 4 Regression models with transformed and untransformed variables in ascending order of adjusted R-squared

From: The impact of additive or substitutive clinical study design on the negotiated reimbursement for oncology pharmaceuticals after early benefit assessment in Germany

Independent Variable

Coefficient

SE

95% CI

t statistic

P value

R2

adj R2

Additive premiums

(1) Basis regression model using all variables untransformed, and additive premiums as the dependent variable

  EU Prices

1.3141259

1.00407225

−1.1427504 – 3.77100219

1.30879616

0.23849493

0.654

0.309

  Comparable drugs

−0.1535998

0.23822837

−0.7365236 – 0.42932406

− 0.6447585

0.54293375

  Added benefit

9034.29827

10,716.7639

−17,188.678 – 35,257.275

0.84300618

0.4315413

  AnTC ACT

−0.0486107

0.28074618

−0.7355719 – 0.63835042

− 0.1731484

0.86822835

  Study design dichotomized

7356.39568

15,843.3671

−31,410.927 – 46,123.7184

0.46432022

0.65878822

  Target population

−1.6576633

1.20885101

−4.6156151 – 1.30028857

−1.3712718

0.21936371

  Constant

52,107.00377

20,198.79989

2682.320947–101,531.6866

2.579707906

0.04178586*

(2) Basis regression model using all variables untransformed, and log additive premiums as the dependent variable

  EU Prices

0.00001931

0.00001709

−0.00002252 – 0.00006114

1.12939086

0.30185338

0.705

0.410

  Comparable drugs

−0.00000257

0.00000406

−0.00001249 – 0.00000736

−0.63303948

0.55005850

  Added benefit

0.19608572

0.18245474

−0.25036495 – 0.64253639

1.07470883

0.32381185

  AnTC ACT

−0.00000076

0.00000478

−0.00001245 –0.00001094

−0.15849576

0.87926624

  Study design dichotomized

0.07529218

0.26973604

−0.58472812 – 0.73531249

0.27913283

0.78951472

  Target population

−0.00003937

0.00002058

−0.00008973 – 0.00001099

−1.91280535

0.10430143

  Constant

10.84596964

0.34388803

10.00450596–11.68743333

31.53924778

0.00000007*

(3) Basis regression model with interaction AnTC ACT*Target population, and log additive premiums as the dependent variable

  EU Prices

0.00002490

0.00001697

−0.00001871 – 0.00006852

1.46787027

0.20206636

0.775

0.460

  Comparable drugs

−0.00000580

0.00000467

−0.00001781 – 0.00000620

−1.24238121

0.26918568

  Added benefit

0.04432483

0.21293062

−0.50303075 – 0.59168041

0.20816559

0.84331349

  AnTC ACT

−0.00000367

0.00000514

−0.00001688 – 0.00000954

− 0.71446967

0.50689617

  Target population

−0.00013334

0.00007798

−0.00033380 – 0.00006712

−1.70982331

0.14799077

  AnTC ACT*Tar. pop

0.00000000

0.00000000

0.00000000–0.00000001

1.24538235

0.26817087

  Study design dichotomized

−0.04186251

0.27475003

−0.74812996 – 0.66440493

− 0.15236582

0.88485596

  Constant

11.71190494

0.76927118

9.73443041–13.68937947

15.22467656

0.00002217*

(4) Bivariate regression model using statistical significant variables, and additive premiums as the dependent variable

  EU-prices

1.00815416

0.49637946

−0.09784821 – 2.11415654

2.031015043

0.069686298

0.554

0.465

  Target population

−1.80975847

0.78477917

−3.55835544 – −0.06116149

−2.306073507

0.043799202*

  Constant

61,129.98695

7879.338538

43,573.72662788–78,686.24727887

7.7582638

0.00001539*

(5) Bivariate regression model using statistical significant variables, and log additive premiums as the dependent variable

  EU-prices

0.00001578

0.00000860

−0.00000338 – 0.00003494

1.83493479

0.09639450

0.606

0.528

  Target population

−0.00003976

0.00001360

−0.00007005 – − 0.00000946

−2.92431420

0.01518788*

  Constant

11.02820319

0.13649721

10.72406846–11.33233792

80.79435053

0.00000000*

(6) Bivariate Regression model using log EU-prices and target population, and log additive premiums as dependent variable

  Log EU-prices

0.14680259

0.06653394

−0.00144427 – 0.29504945

2.20643159

0.05187319

0.646

0.575

  Target population

−0.00003672

0.00001317

−0.00006606 – --0.00000738

−2.788982

0.0191532*

  Constant

9.90990728

0.57996394

8.61766708–11.20214748

17.08710928

0.00000001

(7) Multivariate regression model using statistical significant variables, study design, and log additive premiums as the dependent variable

  EU-prices

0.00000695

0.00000928

−0.00001405 – 0.00002794

0.74851855

0.47325401

0.707

0.610

  Target population

−0.00004912

0.00001344

−0.00007953 – − 0.00001870

−3.6531866

0.00529125*

  Study design trichotomized

0.18888016

0.10707861

−0.05334849 – 0.43110881

1.76393916

0.11156758

  Constant

10.71083426

0.21852857

10.21648828–11.20518023

49.01342718

0.00000000*

(8) Basis regression model with interaction AnTC*target population, trichotomized study design, and log additive premiums as the dependent variable

  EU Prices

0.00001430

0.00001280

−0.00001859 – 0.00004719

1.11734172

0.31464184

0.878

0.708

  Comparable drugs

−0.00000489

0.00000346

−0.00001379 – 0.00000400

−1.41398786

0.21649968

  Added benefit

−0.26610636

0.21675823

−0.82330113 – 0.29108840

−1.22766442

0.27421249

  AnTC ACT

−0.00000604

0.00000394

−0.00001616 – 0.00000409

−1.53330417

0.18577935

  Target population

−0.00019253

0.00005941

−0.00034526 – − 0.00003980

−3.24045751

0.02293760*

  AnTC ACT*Tar. pop

0.0000000029

0.00000000

0.00000000–0.00000001

2.50391081

0.05423011*

  Study design trichotomized

0.29015387

0.13996625

−0.06964081 – 0.64994856

2.07302748

0.09288142

  Constant

11.81575737

0.51914558

10.48125116–13.15026357

22.76000749

0.00000304*

Multiplicative premiums

(9) Basis regression model using all variables untransformed, and multiplicative premiums as the dependent variable

  EU Prices

0.01863379

0.03046329

−0.0559072 – 0.09317478

0.61167992

0.56319335

0.708

0.417

  Comparable drugs

−0.0170363

0.00722779

−0.0347221 – 0.00064944

−2.3570588

0.05651068

  Added benefit

318.494844

325.143866

−477.10353 – 1114.09322

0.97955052

0.36513746

  AnTC ACT

0.00768265

0.00851777

−0.0131596 – 0.02852487

0.90195532

0.40183525

  Study design dichotomized

−606.94617

480.68369

− 1783.1368 – 569.244448

−1.2626727

0.25356019

  Target population

−0.0694163

0.03667623

−0.1591598 – 0.02032722

−1.8926775

0.10725321

  Constant

1329.140422

612.8264012

−170.39176 – 2828.67261

2.168869389

0.073175976

(10) Basis regression model using all variables untransformed, and log multiplicative premiums as the dependent variable

  EU Prices

0.00004607

0.00009979

0.12277548–9.94718239

0.46161051

0.66062263

0.815

0.630

  Comparable drugs

−0.00005089

0.00002368

−0.00019812 – 0.00029025

−2.14954836

0.07515311

  Added benefit

2.23125516

1.06511407

−0.00010883 – 0.00000704

2.09485090

0.08105271

  AnTC ACT

−0.00000966

0.00002790

−0.37498507 – 4.83749539

−0.34604099

0.74112304

  Study design dichotomized

−2.19341764

1.57463515

−0.00007793 – 0.00005862

−1.39296880

0.21305128

  Target population

−0.00025771

0.00012014

−6.04641104 – 1.65957577

−2.14498038

0.07562852

  Constant

5.03497894

2.00751141

−0.00055169 – 0.00003628

2.50806990

0.04602317*

(11) Basis regression model using all variables untransformed, trichotomized study design, and log multiplicative premiums as the dependent variable

  EU Prices

0.00002793

0.00010268

−0.00022332 – 0.00027919

0.27202759

0.79471928

0.822

0.646

  Comparable drugs

−0.00004310

0.00002491

−0.00010406 – 0.00001786

−1.72989859

0.13437373

  Added benefit

0.81020226

1.23677559

−2.21607858 – 3.83648311

0.65509238

0.53669959

  AnTC ACT

−0.00001518

0.00002732

−0.00008202 – 0.00005167

− 0.55547716

0.59865283

  Study design trichotomized

1.51393827

1.00119466

−0.93589681 – 3.96377335

1.51213179

0.18125773

  Target population

−0.00021019

0.00010064

−0.00045646 – 0.00003607

−2.08848182

0.08176979

  Constant

2.41624100

2.26119548

−3.11670503 – 7.94918702

1.06856794

0.32635841

(12) Univariate regression model using log AnTC ACT, and log multiplicative premiums as the dependent variable

  Log AnTC ACT

−0.931522444

0.036401089

−1.0116407 – − 0.8514042

−25.59051002

0.000000000037*

0.983

0.981

  Constant

10.68460638

0.326107398

9.96684884–11.4023639

32.76407232

0.000000000003*

(13) Univariate regression model using log AnTC ACT, trichotomized study design, and log multiplicative premiums as the dependent variable

  Log AnTC ACT

−0.9010848

0.04282724

−0.9965099 – − 0.8056598

−21.03999339

0.0000000013*

0.985

0.983

  Study design trichotomized

0.2069238

0.16343973

−0.1572426 – 0.57109022

1.266055713

0.234191404

  Constant

9.947609983

0.663086674

8.4701608–11.4250592

15.00197541

0.0000000349*

  1. adj adjusted, AnTC ACT Annual therapeutic costs of appropriate comparative therapy, CI confidence interval, SE standard error
  2. * ≤ 0.05