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Figure 5 | BMC Neurology

Figure 5

From: A retrospective analysis of hand tapping as a longitudinal marker of disease progression in Huntington’s disease

Figure 5

Number of patients required for various effect sizes and follow-up times. Since patients decrease (on average) at rate of 5.1 taps per year, a therapeutic intervention that results in a 20% improvement would have a rate of decline of 4.06 taps per year. For a two group experiment, this effect could be detected with 80% power after one year if 727 patients are recruited, or after four years with 48 patients. These estimates are approximate and depend on the proportion of individuals with long versus short CAG repeats, the number of patients lost to follow up, and the design of the study.

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