The perceived advantages and disadvantages of presymptomatic testing for Machado-Joseph disease: development of a new self-response inventory.

This study describes the construction of a self-response inventory to evaluate the perception of advantages and disadvantages of the Machado-Joseph disease presymptomatic testing, in 44 individuals at-risk for this disease. The results showed that the reliability of this inventory was satisfactory. Factor analysis revealed a bidimensional structure: perceived advantages (pros) and perceived disadvantages (cons) of presymptomatic testing. Social desirability was found unrelated to the total scores of our inventory. Additional correlation studies, with other scales, confirmed the convergent validity of the instrument. These results suggest adequate construct validity. This inventory thus seems to be a proper instrument to assess expectations involved in the decision-making process of Machado-Joseph disease presymptomatic testing.