Table 3.
The results of pharmacodynamic model building and selection.*
| Active moiety | Model | Number of model parameters | Model description | -LL | AIC† |
|---|---|---|---|---|---|
| Placebo | PD (1) | 6 | Only placebo effect, with variable scale and shape | 1294 | 2.198 |
| PD (2) | 9 | As above with variable baseline | 1245 | 2.126 | |
| PD (3) | 12 | As above with variable tlag | 1240 | 2.128 | |
| DEX | PD (4) | 3 | Emax with effect compartment | 1235 | 2.351 |
| PD (5) | 4 | Sigmoidal Emax | 1233 | 2.350 | |
| PD (6) | 7 | As above with variable baseline placebo effect§ | 1247 | 2.344 | |
| PD (7) | 10 | As above with variable extent of placebo effect§ | 1218 | 2.344 | |
| PD (8) | 13 | As above with variable tlag of placebo effect§ | 1208 | 2.337 | |
| DOR | PD (9) | 4 | As (5) | 1397 | 2.365 |
| PD (10) | 7 | As (6) | 1268 | 2.158 | |
| PD (11) | 10 | As (7) | 1315 | 2.247 | |
| PD (12) | 13 | As (8) | 1250 | 2.151 | |
| DEX/DOR | PD (13) | 4 | As (4) with competitive effect between DEX and DOR | 1332 | 2.263 |
| PD (14) | 5 | As (5) with competitive effect between DEX and DOR | 1315 | 2.230 | |
| PD (15) | 6 | As above with variable ke0 for DEX and DOR | 1318 | 2.238 | |
| PD (16) | 12 | As above with variable baseline and effect of placebo§ | 1214 | 2.066 |
*
For more details see Appendix.
†
The best-fit model with the lowest AIC value is indicated in italics. ‡ P-value for the statistical significance of improvement in -LL compared with the previous model on the list.
§
These variable effects refer to inter-occasion (IOV) (intra-individual) differences in placebo parameter values between different study arms.