Supplementary Material for: Prevalence of essential tremor among Greeks aged 65 years or older: Results from the HELIAD study

Introduction
The prevalence of essential tremor (ET) demonstrates substantial differences across study populations and has been assessed in more than 40 population-based studies, but never in Greece. We directly estimated the prevalence of ET in community-dwelling adults aged 65 years and older, which was the age group expected to have the highest prevalence.
Methods
Participants in a population-representative cohort aged ≥65 years underwent a neurological evaluation. ET was operationally defined as a Bain and Findley scale score ≥4 on the Archimedes’ spirals drawn with the more affected arm, excluding alternative causes of tremor. In a subset of participants, we validated this against diagnoses of ET assigned based on videotaped neurological examination. Logistic regression models were performed to assess independent effects of age and sex on prevalence.
Results
172 of 1,926 participants were classified as having ET, corresponding to a crude prevalence of 8.9% (95% Confidence interval [CI] = 7.7%, 10.2%). The prevalence of ET increased with increasing age (65-69: 6.4%; 70-74: 6.6%; 75-79: 12.1%; ≥80: 14.1%, X2 test, p<0.001) and was higher in male than female participants (11.7% vs 7.0%, X2 test, p<0.001). Both age and sex were significant predictors of ET, when assessed simultaneously using logistic regression - odds ratio (95% CIs) = 1.07 (1.04, 1.10) and 1.54 (1.11, 2.12), respectively.
Discussion
Our study provides the first estimate of ET prevalence in Greece and shows that ET is highly prevalent, as it affects 8.9% of Greeks aged ≥65.