1. A widely used scale in PD research for quantification of functional activities is the Schwab and England ADL scale

 http://www.rehabmeasures.org/Lists/RehabMeasures/DispForm.aspx?ID=1012 

2. Another functional health scale that is validated in PD and provides a linear outcome based on Item Response Theory clinimetrics is the ALDS (AMC Linear Disabilty Scale). The linearity of the scores makes it very useful for calculations. Also, it is not disease specific.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1327691/

Good luck!

To my knowledge there are no true surrogates of the Hoehn & Yahr scale. Alternatives are cited in the answer above. Other suggestion can come by the first (hoehnyahr) of the two papers attached. 

Regarding patient reported outcome the second paper (Reddy et al) attached might provide interesting insights.

Kind M. Sardina,

I repeatedly had problems downloading the attachment by Reddy [message of damaged file]: it would be interesting

thank you in advance [[email protected]]

Thank you for the references, they've proved to be an interesting read (especially the Reddy paper). 

I'm finding movement disorders specialists using the UPDRS (United Parkinson's Disease Rating Scale) or MDS-UPDRS (Movement Disorders Society UPDRS)  http://onlinelibrary.wiley.com/doi/10.1002/mds.22340/full

My patients with PD and their caregivers have benefitted from learning about this scale since it's much more detailed than H&Y, and shows them all kinds of different symptoms, so they can clearly see their strengths and weaknesses.  

Goetz, C. G., Tilley, B. C., Shaftman, S. R., Stebbins, G. T., Fahn, S., Martinez‐Martin, P., ... & LaPelle, N. (2008). Movement Disorder Society‐sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS‐UPDRS): Scale presentation and clinimetric testing results. Movement disorders, 23(15), 2129-2170.

You can find a nice description here of all three scales mentioned in this thread.  I've used it for savvy patients and caregivers.  http://neurosurgery.mgh.harvard.edu/functional/pdstages.htm

Best of luck with your focus groups!

The MDS-UPDRS is indeed a widely used and helpful scale, but it mostly measures symptomatic outcome. The H&Y is meant mostly for measuring functional outcome.

Carrie and Vincent, thanks for your replies.  Given the "focus group" setting in which we will be querying our participants, completion of the UPDRS or MDS-UPDRS isn't going to be the best option- albeit a great suggestion.  But the suggestion did stir an interest in determining the value of using just the ADL component of the scale, as it is primarily an interview method of questioning.  Looking further into the option, I came across a nice study that analyzed the longitudinal metric attributes of three PD disability scales, using the H&Y as the reference measure of PD progression (http://onlinelibrary.wiley.com/doi/10.1111/j.1524-4733.2006.00131.x/pdf).  The basic conclusion of the study states the three scales (SES, UPDRS-ADL, and ISAPD) proved adequate for assessment of PD disability; the scores of the three scales - taken over two time points - showed a similar trend of "disease worsening" as the H&Y.  So, it would appear that either of these three "interview-based" assessments may provide a reasonable sense of disease severity in place of the H&Y.

Dear David,

would you please post directly the paper ?

I wasn't able do run the link: thank you in advance, Mauro Colombo

Here is the article by Martinez-Martin, et al. 2006.

just downloaded: thank you so much, Mauro

An alternative is using the NIH toolbox and selecting the criteria that would be appropriate to use.  The NIH toolbox allows you to customize a measure and collect the data.  Its purpose is to standardize measures across illnesses.