Clinical variables associated with treatment changes in Parkinson's disease: results from the longitudinal phase of the REASON study.

To assess over a period of 9 months in a sample of Italian Parkinson's disease (PD) patients reasons leading the neurologist to modify dopaminergic treatment and patients' causes of dissatisfaction with ongoing therapy. To evaluate the influence of disease severity on therapy persistence. A disease severity balanced sample of PD patients with stable anti-parkinsonian drugs (APD) treatment was enrolled and evaluated every 3 months. Patients requiring APD treatment modifications were discontinued from the study. The probability to modify APD treatment is greater for higher motor (UPDRS scores) and non-motor symptoms (NMSS score) severity. Both from neurologist's and patient's perspective, motor symptoms were the main determinants underlying APD treatment modifications. Non-motor symptoms were cause of dissatisfaction with ongoing APD treatment for 52 % of the patients, while only 36 % of the neurologists considered these as valid reasons for therapy change. REASON is the first study in PD patients that prospectively examined reasons driving APD treatment changes. Results show that the disease severity significantly increases the probability of APD treatment change. Patients attribute greater relevance than neurologists to non-motor symptoms as reason requiring treatment changes. This confirms that patient and neurologist perceptions only partially overlap.