Comparison of clinical features among Parkinson's disease subtypes: A large retrospective study in a single center

Introduction: Tremor dominant (TD), postural instability/gait difficulty (PIGD), and akinetic-rigid (AR) subtypes are widely used in classifying patients with Parkinson's disease (PD). Methods: We compared clinical characteristics between PD subtypes in a large retrospective cohort. Between 1998 and 2016, we included a total of 1003 patients with PD in this retrospective study. Six hundred ninety-four patients had more than one visit. Data were collected regarding motor/non-motor symptoms at the initial/final visits. Based on the prominent symptom at the initial visit, we classified patients into one of the four subtypes: TD, AR, gait difficulty, and mixed. Rapid progression was defined by emergence of falls, dementia, or dependency within 5 years after onset. Results: TD was the most prevalent subtype (44%), followed by AR (29%), mixed (18%), and gait difficulty (9%). Rapid progression was observed more frequently in gait difficulty compared to AR (OR: 3.59 P < 0.001). Hallucinations at the final visit were more likely to occur in AR (OR: 2.36, P = 0.005) and mixed (OR: 3.28, P < 0.001) compared to TD. Conclusions: Our findings provide support for a distinction of four different PD subtypes: TD, AR, gait difficulty, and mixed. The gait difficulty subtype was distinguishable from the AR subtype.