Research Article

A Two-Stage Joint Model for Nonlinear Longitudinal Response and a Time-to-Event with Application in Transplantation Studies

Table 2

Parameter estimates, SE, and 95% confidence/credibility intervals from proportional hazards Cox model for graft survival for plug-in method (a), sampled covariates (b), and fully Bayesian approach (c, d, e).
(a) Graft survival, plug-in

Effect Parameter log(HR) SE (95% CI)

e x p ( 𝜙 1 ) 𝛾 1 0.052 0.022 (0.009; 0.095)
e x p ( 𝜙 2 ) 𝛾 2 −0.005 0.005 (−0.015; 0.005)
e x p ( 𝜙 3 ) 𝛾 3 0.053 0.158 (−0.257; 0.363)

(b) Graft survival, sampling two-stage

Effect Parameter log(HR) SE (95% CI)

e x p ( 𝜙 1 ) 𝛾 1 0.053 0.024 (0.006; 0.100)
e x p ( 𝜙 2 ) 𝛾 2 −0.006 0.008 (−0.022; 0.010)
e x p ( 𝜙 3 ) 𝛾 3 0.055 0.185 (−0.308; 0.418)

(c) Graft survival, fully Bayesian, Weibull

Effect Parameter log(HR) SE (95% HPD)

e x p ( 𝜙 1 ) 𝛾 1 0.058 0.023 (0.013; 0.103)
e x p ( 𝜙 2 ) 𝛾 2 −0.005 0.008 (−0.020; 0.011)
e x p ( 𝜙 3 ) 𝛾 3 0.056 0.180 (−0.299; 0.411)

(d) Graft survival, fully Bayesian, Cox

Effect Parameter log(HR) SE (95% HPD)

e x p ( 𝜙 1 ) 𝛾 1 0.056 0.023 (0.010; 0.101)
e x p ( 𝜙 2 ) 𝛾 2 −0.006 0.008 (−0.022; 0.010)
e x p ( 𝜙 3 ) 𝛾 3 0.055 0.171 (−0.280; 0.390)

(e) Graft survival, fully Bayesian, piecewise constant hazard

Effect Parameter log(HR) SE (95% HPD)

e x p ( 𝜙 1 ) 𝛾 1 0.054 0.024 (0.007; 0.102)
e x p ( 𝜙 2 ) 𝛾 2 −0.005 0.009 (−0.022; 0.012)
e x p ( 𝜙 3 ) 𝛾 3 0.054 0.179 (−0.297; 0.405)