Table 2.
Summary of estimates from final model using NONMEM and a nonparametric bootstrap
| NONMEM | Bootstrap | |||||
|---|---|---|---|---|---|---|
| Estimate | % RSEa | Median | % RSEa | 2.5th | 97.5th | |
| QTcAbs (ms) | 400 | 0.2 | 400 | 0.4 | 396 | 403 |
| Alpha | 0.333 | Fixed | 0.333 | Fixed | — | — |
| Sex on QTcAbs b | 0.0189 | 13.7 | 0.01911 | 13.8 | 0.0140 | 0.0241 |
| COWS on alpha (slope) | 0.00151 | 52.1 | 0.00151 | 51.5 | −0.0000274 | 0.00307 |
| Hydroxyzine on QTcAbs b | 0.00423 | 35.7 | 0.00422 | 36.3 | 0.00115 | 0.00715 |
| Methadone on QTcAbs b | 0.0153 | 18.4 | 0.01522 | 17.4 | 0.0101 | 0.0210 |
| Age on QTcAbs (ms/year) | 0.324 | 7.0 | 0.32158 | 12.9 | 0.232 | 0.406 |
| Holter vs. computerized on QTcAbs b | −0.00423 | 24.6 | −0.00421 | 25.2 | −0.00624 | −0.00206 |
| Central vs. noncentral reading on QTcAbs b | −0.021 | 11.5 | −0.02097 | 13.1 | −0.0266 | −0.0158 |
| Concentration‐related slope (ms/ng/mL)b | −0.0507 | 168.8 | −0.04617 | 181.1 | −0.225 | 0.110 |
| Codeine on QTcAbs b | 0.00327 | 35.2 | 0.00333 | 33.7 | 0.00102 | 0.00551 |
| Oxycodone on QTcAbs b | −0.00378 | 43.4 | −0.00381 | 42.9 | −0.00694 | −0.000448 |
| Phencyclidine on QTcAbs b | 0.00861 | 44.1 | 0.00902 | 42.3 | 0.000451 | 0.0159 |
| Barbiturates on QTcAbs b | 0.0124 | 38.9 | 0.01223 | 40.4 | 0.00205 | 0.0219 |
| Cocaine on QTcAbs b | 0.00428 | 28.0 | 0.00427 | 28.0 | 0.00193 | 0.00651 |
| IIV on QTcAbs (ms) | 14.3 | 5.2 | 14.2 | 5.2 | 13.5 | 15 |
| IIV on concentration‐related slope (ms/ng/mL) | 0.767 | 33.1 | 0.748 | 34.8 | 0.5 | 1 |
| RE (ms) | 10.6 | 3.3 | 10.6 | 3.1 | 10.3 | 11 |
COWS, Clinical Opioid Withdrawal Scale; IIV, interindividual variability; QTc, heart rate‐corrected QT; QTcAbs, base model for QTc using the reduced dataset included a parameter describing the QTc in the absence of buprenorphine.
aRSE = relative standard error (100 × SE divided by the estimate). bFractional change in QTcAbs.