Gerry thanks for this. I find it interesting that this study used primarily non motor symptoms as its categories and was able to predict progression. It seems a good start but somehow incomplete as a categorisation system, perhaps more like a symptom cluster for predicting outcomes.

Here is an earlier article which gives a review of other classification systems that have been developed. I wonder what system will become the standard of the future.
http://www.medscape.com/viewarticle/781510