title: Evolution of association between renal and liver functions while awaiting heart transplant: An application using a bivariate multiphase nonlinear mixed effects model.
abstract: In many longitudinal follow-up studies, we observe more than one longitudinal outcome. Impaired renal and liver functions are indicators of poor clinical outcomes for patients who are on mechanical circulatory support and awaiting heart transplant. Hence, monitoring organ functions while waiting for heart transplant is an integral part of patient management. Longitudinal measurements of bilirubin can be used as a marker for liver function and glomerular filtration rate for renal function. We derive an approximation to evolution of association between these two organ functions using a bivariate nonlinear mixed effects model for continuous longitudinal measurements, where the two submodels are linked by a common distribution of time-dependent latent variables and a common distribution of measurement errors.
authors.affiliation: Department of Quantitative Health Sciences, and Heart and Vascular Institute, Cleveland Clinic, Cleveland, USA.
authors.forename: Jeevanantham
authors.initials: J
authors.lastname: Rajeswaran
authors.affiliation: Department of Quantitative Health Sciences, and Heart and Vascular Institute, Cleveland Clinic, Cleveland, USA.
authors.forename: Eugene H
authors.initials: EH
authors.lastname: Blackstone
authors.affiliation: Department of Quantitative Health Sciences, and Heart and Vascular Institute, Cleveland Clinic, Cleveland, USA.
authors.forename: John
authors.initials: J
authors.lastname: Barnard
mesh_terms: D000465:Algorithms; D005919:Glomerular Filtration Rate; D016027:Heart Transplantation; D006801:Humans; D007668:Kidney / Q000502:physiology*; D008099:Liver / Q000502:physiology*; D017711:Nonlinear Dynamics; D057234:Preoperative Period
keywords: Nonlinear model; additive regression; bivariate mixed effects model; evolution of correlation; mixed effects model; temporal decomposition