Background: Chronic stimulation of the ventral intermediate nucleus of the thalamus with deep brain stimulation has been a mode of treatment for tremor in both Parkinson’s Disease (PD) and Essential Tremor (ET) (Koller 2000). This mechanistic hypothesis suggests ET and PD action tremor may have similar central origins. There are also similar comorbid conditions that emerge within the first 2 years of diagnosis of the respective diseases. This study analyzed comorbidities among patients diagnosed with ET and PD using claims data from Truven Health Analytics MarketScan® Commercial, and Medicare Supplemental databases (2013-2019).

Methods: Using the Truven Health Analytics MarketScan database, 3 cohorts of adult patients (40+) with ET (N=13,559), PD (N=18,193) and those without ET or PD (N=633,066) were identified.

Results: In the 24 months following index date, patients 65 years or older in the ET and PD cohorts had a higher prevalence of the following disorders compared to those without ET or PD. Accidental Falls: 14.1% vs. 24.5% vs. 2.0%; Bradykinesia: 14.9% vs. 10.0% vs. 0.3%; Depression: 22.4% vs. 25.1% vs. 14.4%; Fatigue: 28.1% vs. 35.7% vs. 17.4%; Sleep Disorders: 30.3% vs. 30.5% vs. 14.3%; Additionally, of those patients who had pharmacy and medical records ≥12-months prior to and ≥24-months following the index date, only 10.7% of ET patients did not have a diagnosis claim at any point for PD in their history, and 20.4% of PD patients did not have a diagnosis claim at any point for ET in their history.

Conclusion: There are similarities in central origins for both ET and PD relating to action tremor of the hands along with several overlapping comorbidities within 2 years following diagnosis. These shared characteristics may explain why many patients often have a diagnosis of both ET and PD within 2 years of their index date.