Objective:

To conduct a literature review using real-world evidence on the most common pharmacotherapies used in treating essential tremor (ET).

Background:

ET is among the most common movement disorders in the US. Current treatments include pharmacological treatments and surgical interventions, though many patients continue to lack adequate tremor control. Syntheses of published real-world evidence on ET pharmacotherapies are lacking.

Design/Methods:

We conducted a comprehensive literature review of English-language studies published between 1966-2022 using PubMed. The review targeted non-clinical trial studies of adults with ET evaluating propranolol, primidone, gabapentin, and/or topiramate, and reporting at least upper limb tremor efficacy, safety/adverse events, tolerability, and/or treatment patterns. Studies reporting ≤10 subjects were excluded.

Results:

We identified 236 studies. Following title and abstract screening, 75 full-text studies were assessed, with 15 included in data extraction. Patient- or clinician-validated scales were used in 2/15 studies. Activities of daily living and quality of life outcomes were not commonly reported. Up to 81% and 55% of patients used propranolol and primidone, respectively. Gabapentin (30%) and topiramate (20%) were used less frequently. Though clinical response definitions varied, propranolol demonstrated response in 37-56% of patients, and primidone in 43-55% of patients among studies with ≥50 evaluable patients. Approximately one-quarter of patients reported responding to gabapentin or topiramate. Discontinuation rates varied widely across studies, from 10-70% for both propranolol and primidone. Gabapentin and topiramate had discontinuation rates from 26-86% and 26-58%, respectively. Usage, efficacy, and discontinuation were not characterized by line of therapy (i.e. initial vs subsequent treatments) in the assessed studies.

Conclusions:

Currently available ET pharmacotherapies may not provide adequate efficacy for many patients, highlighting substantial unmet need. We identified several gaps in the published evidence base, including evaluation of commonly-used ET medications by line of therapy and reporting on validated measures to enable comparisons to new ET pharmacotherapies.