Impact of complications and comorbidities on treatment costs and health-related quality of life of patients with Parkinson's disease

Background: Data regarding both drug-related and non-drug-related costs in patients with Parkinson's disease (PD) are scarce, mainly due to the difficulties in data acquisition in experimental designs. Likewise, the reported impact of drug costs on total direct costs varies across different studies. In addition, the influence of comorbidities on both treatment costs and health-related quality of life has not been adequately evaluated. Methods: A sample of office-based neurologists (n = 315) in Germany was asked to examine up to five consecutive patients with PD (n = 1449) on a specified day during the study period. Patients of all ages were eligible and their evaluation was performed using standardized questionnaires. Results: PD-specific therapy costs increased with the stage of the disease, early onset of the disease and disease duration. The major costs were due to PD-related therapy, whereas other medications only resulted in minor costs. Disease stage mainly influenced direct therapy costs, with an observed increase of total daily costs from €7.3 to €11.3/day. In addition, disease onset at age < 65 years resulted in total daily costs of €11.2 compared to late onset of disease (> 75 years) with daily therapy costs of €5.3. In this patient group neuropsychiatric comorbidities such as dementia and depression were only insufficiently treated. In addition, these comorbidities severely affected health-related quality of life. Conclusion: Therapy costs were influenced by disease stage, disease onset as well as present comorbidities. Furthermore, comorbidities such as depression and dementia were diagnosed but were not adequately treated