Model number | Covariate model | ΔOFV |
Comparison model | |||||
1 | Basic model | 0.0 | ||||||
2 | Does weight influence CL | 77.8 | 1 | Yes | ||||
(CL = θ_{1} × weight, V = θ_{2}) | ||||||||
3 | Is an intercept required? | 0.0 | 2 | No | ||||
(CL = θ_{1} + θ_{2} × weight, V = θ_{3}) | ||||||||
4 | Does PCA influence CL? | 98.0 | 1 | Yes | ||||
(CL = θ_{1} × PCA^{θ2}, V = θ_{3}) | ||||||||
5 | Does creatinine concentration influence CL? | 100.1 | 1 | Yes | ||||
(CL = θ_{1} × creatinine^{θ2}, V = θ_{3}) | ||||||||
6 | Can 1/creatinine be substituted for creatinine^{θ2}? | −4.9 | 5 | Yes | ||||
(CL = θ_{1} / creatinine, V = θ_{2}) | ||||||||
7 | Does adding weight to CL improve model 6? | 57.3 | 6 | Yes | ||||
(CL = θ_{1} × weight / creatinine, V = θ_{2}) | ||||||||
8 | Does adding PCA improve model 7? | 0.0 | 7 | No | ||||
(CL = θ_{1} × weight / creatinine × PCA^{θ2}, V = θ_{3}) | ||||||||
9 | Does weight influence V? | 73.5 | 7 | Yes | ||||
(CL = θ_{1} × weight / creatinine, V = θ_{2} × weight) | ||||||||
10 | Does adding IV nutrition improve model 9? | 8.2 | 9 | Yes3-150 | ||||
(CL = θ_{1} × weight / creatinine × (1 + θ_{2}(NT)), V = θ_{3} × weight) | ||||||||
11 | Does adding gestational age <35 weeks improve model 9? | 7.9 | 9 | Yes3-150 | ||||
(CL = θ_{1} × weight / creatinine × (1 + θ_{2} (GA)), V = θ_{3} × weight) |
ΔOFV = difference in objective function value (>7.9 is significant at p<0.005 for the addition of 1 parameter); θ_{1...5} = parameter to be estimated; V = volume of distribution; CL = clearance; PCA = postconceptual age; NT = 1 if patient given IV nutrition or 0 otherwise; GA = 1 if gestational age is less than 35 weeks or 0 otherwise;
↵3-150 Borderline significance, omitted from the final model.