ET is one of the most common adult-onset movement disorders; there has only been one other attempt to derive the number affected in the US. This is the first study to provide age-specific and overall estimates for the number of affected adults.

A targeted literature review was conducted to identify population-based studies from 2001-present that measured ET prevalence among adults based on an explicit diagnosis of ET. We identified seven studies reporting the number of ET patients and the total population by specified non-overlapping age groups. Crude age-group-specific prevalences were calculated for each study and an age-group specific weighted average across studies was used for estimation.  The weighted age-group specific prevalences were applied to 2018 US population estimates for adults.  The lowest and highest estimates in each age group were used to generate an age-specific prevalence range.  

This analysis, which estimates that 6.4M adults in the US have ET, is similar, but not identical, to a prior estimate of ~7M across all age groups. Furthermore, we provide the first estimates of prevalence within each decade of age. These data are valuable in understanding the burden of this disease on a population level and in planning therapeutic and public health initiatives.  Future studies should seek to understand the number of adults diagnosed and treated for ET, to assess the humanistic and economic burden for patients, their families, and society.