• Seyed-Mohammad Fereshtehnejad, Silvia Rios Romenets, Julius B M Anang, Véronique Latreille, Jean-François Gagnon, and Ronald B Postuma.
• Division of Clinical Geriatrics, Department of Neurobiology, Care Sciences, and Society, Karolinska Institutet, Stockholm, Sweden.
• JAMA Neurol. 2015 Aug 1;72(8):863-73.

ImportanceThere is increasing evidence that Parkinson disease (PD) is heterogeneous in its clinical presentation and prognosis. Defining subtypes of PD is needed to better understand underlying mechanisms, predict disease course, and eventually design more efficient personalized management strategies.ObjectivesTo identify clinical subtypes of PD, compare the prognosis and progression rate between PD phenotypes, and compare the ability to predict prognosis in our subtypes and those from previously published clustering solutions.Design, Setting, And ParticipantsProspective cohort study. The cohorts were from 2 movement disorders clinics in Montreal, Quebec, Canada (patients were enrolled during the period from 2005 to 2013). A total of 113 patients with idiopathic PD were enrolled. A comprehensive spectrum of motor and nonmotor features (motor severity, motor complications, motor subtypes, quantitative motor tests, autonomic and psychiatric manifestations, olfaction, color vision, sleep parameters, and neurocognitive testing) were assessed at baseline. After a mean follow-up time of 4.5 years, 76 patients were reassessed. In addition to reanalysis of baseline variables, a global composite outcome was created by merging standardized scores for motor symptoms, motor signs, cognitive function, and other nonmotor manifestations.Main Outcomes And MeasuresChanges in the quintiles of the global composite outcome and its components were compared between different subtypes.ResultsThe best cluster solution found was based on orthostatic hypotension, mild cognitive impairment, rapid eye movement sleep behavior disorder (RBD), depression, anxiety, and Unified Parkinson's Disease Rating Scale Part II and Part III scores at baseline. Three subtypes were defined as mainly motor/slow progression, diffuse/malignant, and intermediate. Despite similar age and disease duration, patients with the diffuse/malignant phenotype were more likely to have mild cognitive impairment, orthostatic hypotension, and RBD at baseline, and at prospective follow-up, they showed a more rapid progression in cognition (odds ratio [OR], 8.7 [95% CI, 4.0-18.7]; P < .001), other nonmotor symptoms (OR, 10.0 [95% CI, 4.3-23.2]; P < .001), motor signs (OR, 4.1 [95% CI, 1.8-9.1]; P = .001), motor symptoms (OR, 2.9 [95% CI, 1.3-6.2]; P < .01), and the global composite outcome (OR, 8.0 [95% CI, 3.7-17.7]; P < .001).Conclusions And RelevanceIt is recommended to screen patients with PD for mild cognitive impairment, orthostatic hypotension, and RBD even at baseline visits. These nonmotor features identify a diffuse/malignant subgroup of patients with PD for whom the most rapid progression rate could be expected.

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