Predictors of motor and non-motor complications of idiopathic Parkinson's disease in a hospital based outpatient clinic incident cohort of 1333 patient.

Objective: To compare the relative incidence rates of motor and non-motor clinical milestones in the disease course of Parkinson's disease (PD) patients with the same disease duration during a 12 years follow-up period.

Methods: We retrospectively identified an incident cohort of PD patients referred to our university hospital outpatient clinic between 2003 and 2015 and conducted independent survival analysis for multiple failures using marginal Cox regression methods to determine cause-specific hazard ratios for each outcome.

Results: 1333 patients experienced 1722 disease-related complications during the 12 years follow-up. Patients with younger age at diagnosis and women have increased relative incidence rates for motor fluctuations and dyskinesias. Men are more likely to experience impulse control disorders (ICD), whereas older patients at diagnosis are less likely to develop ICD. Older age at diagnosis is a strong predictor for the development of freezing of gait (HR (CI 95%) per year increase in age at diagnosis 1.02 (1.01-1.04)), postural hypotension (HR 1.06 (1.04-1.08)) and poor outcome defined as postural instability, hallucinations and dementia (HR 1.06 (1.05-1.07)).

Conclusion: In systematically comparing patients with the same disease duration, we confirm tremendous differences in the incidence rates of major motor and non-motor manifestations for patients with PD, independently for the age at diagnosis, gender and laterality of first signs at onset in an incident cohort of patients referred to a tertiary center. This approach is complementary to data-driven clustering methods and illustrates the effect of disease duration as well as baseline characteristics in the development of disease-related complications.