Characteristics of advanced Parkinson’s disease patients seen in movement disorder clinics - Australian results from the cross-sectional OBSERVE study

Abstract Objectives To evaluate the proportion of Parkinson’s disease (PD) patients identified as having advanced Parkinson’s disease (APD) according to physician’s judgement in Australia. Methods This cross-sectional, non-interventional observational study was performed in movement disorder clinics from 18 countries. Results from Australia are presented. Participants included consecutive adults with PD attending routine clinical visits, or inpatients, who could speak English. The primary outcome was the proportion of patients diagnosed with APD via physician judgement. Results 100 patients were recruited in Australia: 61.0% (95% CI 51.4-70.6%) diagnosed with APD by physician judgement. Patients were 66.6±8.5 years, 65% were male, were living at home (97%), and diagnosed with PD for median 10.7 years (0-30.5 years). Motor fluctuations were present in 68%. For those with APD, referral was predominantly to enable access to device assisted therapies (DAT) (49%), while for non-APD, referral was largely for diagnostic purposes (41%). Patients had a median follow-up at the movement disorder clinic of 4.8 years for those with APD, or 3.6 years for non-APD. While 62% were eligible for DAT, only two-thirds of these received them. The most commonly used DAT was deep brain stimulation (64.3%). There was fair agreement between physician’s judgement and the APD criteria by Delphi method (Cohen’s kappa) 0.325 (95% CI 0.150-0.500) in the Australian subset. Conclusions The definition of APD requires refinement in order to facilitate greater agreement among movement disorder specialists. A third of APD patients eligible for DAT remain untreated. Better referral and education of patients with APD is needed.