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Table 2 Comparison of results from three methods of regression analysis of costs per patient

From: Do the methods used to analyse missing data really matter? An examination of data from an observational study of Intermediate Care patients

 

GLM on complete cases n = 592[[1]]a

GLM on MI dataset n = 717[[2]]b

Heckman on complete cases n = 717, 125 obs censored[[3]]c

 

Variables

Exp (Coeff)

S.E.

Exp (Coeff)

S.E.

Exp (Coeff)

S.E.

Episode Characteristics

Age in 2003

0.996

0.003

0.997

0.002

1.000

0.012

Gender

0.982

0.063

1.009

0.060

1.085

0.281

Lives alone

1.052

0.059

1.047

0.056

1.106

0.275

Barthel score at admission

0.973

0.009**

0.984

0.008*

0.884

0.061*

EQ5D score at admission

0.973

0.090

0.935

0.087

1.400

0.435

Descriptors of IC Service

Acute Admission Avoidance Service

0.930

0.129

0.812

0.092*

6.723

0.960*

Type of IC

3.181

0.079**

3.150

0.070**

5.146

1.274

Transferred before end of IC episode

1.144

0.310

1.259

0.258

1.316

1.422

Completed IC episode

2.094

0.300*

2.396

0.248**

4.611

1.318

Other IC Outcome

2.703

0.337**

2.796

0.287**

4.374

1.475

Patient Died (Reference. Group)

      

Descriptorsof IC-related Services

Referral – Primary

0.777

0.123*

0.764

0.121*

0.936

0.576

Referral – Hospital

0.914

0.158

0.777

0.134

4.523

0.930

Referral – Other

1.001

0.212

0.935

0.195

2.240

0.984

Referral – Social Workers (Reference Group)

      

Alternative to IC – Other

1.053

0.079

1.058

0.077

0.508

0.451

Alternative to IC – Home

1.121

0.074

1.058

0.070

1.112

0.329

Alternative to IC – Hospital (Reference Group)

      

Interactions

Barthel score at admission*Type of IC

1.031

0.018

1.017

0.097

1.131

0.092

Acute Admission Avoidance Service* Type of IC

1.214

0.163

1.217

0.136

0.579

0.752

Transfer before IC end*Type of IC

1.145

0.185

1.176

0.169

1.145

0.825

Completed Episode*Type of IC

1.152

0.195

1.112

0.162

0.240

0.952

Other IC Outcome*Type of IC

0.717

0.708

0.583

0.534

0.773

2.846

Patient died*Type of IC (Reference group)

      

_constant

1140.3

0.421**

951.5

0.360**

345.3

1.866**

N

 

592

717

  

717

Censored obs

     

125

R-Squared

 

0.359

   

0.634

Rho

     

0.950

  1. * 5% level of significance, ** 1% level of significance; Dependent variable: cost per patient for GLM and log of cost per patient for Heckman Selection model;
  2. IC = Intermediate care; aMethod 1 assumes that missing data are MCAR;
  3. bMethod 2 assumes that missing data are MAR; cMethod 3 assumes that missing data are MNAR.