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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.