Objectives: Parkinson’s disease (PD) is associated with significant patient quality of life and economic burden. Motor symptoms include bradykinesia, rigidity, and tremor, and non-motor symptoms include psychosis, dementia, depression, anxiety, and sleep disturbances. Many treatments focus on reducing motor symptoms. There is a lack of treatment options addressing non-motor symptoms even though non-motor symptoms such as psychosis and dementia have a direct impact on caregiver distress, nursing home placement and mortality. The objective of this study was to characterize published cost-effectiveness models, and to understand the extent to which they handle motor and nonmotor symptoms.
Methods: We conducted a targeted review of cost-effectiveness models for PD treatments, published in English since 2000. Information on model objective, structure, health states, population characteristics, time horizon, country and symptoms considered were extracted and summarized.
Results: Fifteen cost-effectiveness models published since 2000 were identified and analyzed. Thirteen used a Markov model structure; one used a decision-tree; and one was a simple cost-minimization calculation. Six of the Markov models basing their health states on the Hoehn and Yahr (HY) scale – a 5-stage scale that considers only motor symptoms. Time horizons for the models ranged from one to 25 years. Ten countries were represented; three models focused on the US. All but two models (for cell replacement therapy and deep brain stimulation) evaluated drug treatments. All models evaluated treatments’ effects in terms of motor complications or motor fluctuations (on/ off periods). Only one model considered the effect of treatment on a non-motor symptom (dementia).
Conclusions: Although PD is associated with both motor and non-motor symptoms, there is a lack of cost-effectiveness models capturing treatment’s effects on non-motor symptoms. This may be due to a lack of standard assessment tools as well as limited treatment options for non-motor symptoms of PD. Further research is needed in this area.
