The present study aims to evaluate the effectiveness and safety of opicapone in a real-world setting at centers for Parkinson's disease located in Italy.

This is a multicenter, prospective, observational cohort study of patients with Parkinson's Disease and early motor fluctuations treated with opicapone in Italy.

Treatment with opicapone will be independent from participation in this observational study and must not be initiated for the purpose of participating in it. Opicapone will be administered according to the local Summary of Product Characteristics (SmPC).

Data on patients will be collected in accordance with routine clinical visits and examinations starting from the date when patient consent is obtained, and for up to two years after start of treatment with opicapone. The collection of the patient-reported outcomes (PRO) and clinician-reported outcomes (ClinRO) will be dictated by the routine clinical practice at each center; thus, scales left blank will not be considered protocol deviations.

Patients will be followed up for a maximum of 2 years (±2 months). Because of the observational design of the study, there are no imposed visits beyond those performed as per clinical practice. Visits are however planned closest to 6 months (±2 months), 12 months (±2 months), 18 months (±2 months), and 24 months (±2 months) after inclusion.

The overall duration of the study will be of approximately 5 years, with 24 months of recruitment and 24 months (±2 months) of follow-up from the last patient in. The End of Study (EOS) is defined as the time when the last enrolled patient has completed 24 months (±2 months) of assessments (unless early termination) after enrolment.

In the event that a patient discontinues opicapone, he/she will be discontinued from the study. Patients discontinued from the study will not be replaced.

Inclusion Criteria:

1. The patient is able to comprehend and willing to provide written informed consent to participate in this study.
2. Patients aged 30 years or older.
3. The patient has a clinical diagnosis of PD according to the diagnostic criteria of United Kingdom (UK) PD Society Brain Bank (2006) or Movement Disorder Society (MDS) Clinical Criteria (2015).
4. Disease severity stages I-III (Hoehn & Yahr Staging).
5. The patient is on treatment with levodopa/DOPA decarboxylase inhibitors (DDCI) for at least 1 year.
6. The patient has signs of wearing off phenomenon/end-of dose motor fluctuations for less than 2 years.
7. Patients starting treatment with opicapone as per local Summary of Product Characteristics (SmPC). Initiation of treatment with opicapone will be independent from participation in this observational study and must not be initiated for the purpose of study participation. The decision to treat patients with opicapone will occur before patients are enrolled in the study.

Exclusion Criteria:

1. The patient has any form of Parkinsonism other than PD.
2. The patient is participating in a clinical trial with an investigational drug or has concluded participation within 30 days.
3. The patient has any contraindication to opicapone according to SmPC.
4. The patient meets criteria for dementia in the Investigator's judgment.
5. The patient is currently treated with catechol-O-methyl transferase (COMT) inhibitors.

The study will be conducted at approximately 20 centers located in Italy and plans to enroll approximately 200 patients with Parkinson's Disease and early motor fluctuations.