Global assessment measures for assessing efficacy in dementia drug trials.

The use of judgment-based global measures of clinical treatment effects has a long history in the regulatory approval of drugs for the treatment of dementia. This paper reviews current use of these measures, noting several practical difficulties with their implementation. Importantly, global measures have usually yielded general estimates of drug effects similar to psychometric test batteries, even though correlations between global and psychometric measures at the individual patient level is modest. Like psychometric tests, global measures can tell us that some clinically detectable effect is present but often yield only limited evidence about what those effects might be. Steps should be taken to improve the specificity of treatment effect description and to incorporate patient/caregiver preferences in global measures about disease treatment in dementia.