Multi-state and Time-varying Covariate Survival Models for Multiple Knee Contractures in People with Cerebral Palsy

Abstract: Cerebral palsy is an umbrella term for a group of neurological disorders, affecting motor function, movement and posture. Contractures, restrictions in the range of motion of joints, are a common problem affecting people living with cerebral palsy. In the present thesis, the effect of having a contracture on one knee, on the hazard for developing a contracture on the other knee, is explored. This is done through various kinds of survival analysis, incorporating multi-state modeling and time-varying covariates respectively. While all models seem to suggest an increased hazard, direct interpretation is cautioned against, since all models suffer from various simplifications and flaws. Suggestions for further research, and improvements to the models, are also given.