To create a convenient staging system for PSP and to use those stages and other disease milestones as outcomes in a prognostic tool useful at the individual patient level.

The existing PSP Rating Scale, published in 2007 by authors LG and PO-S, performs well in quantifying disability but may be inconvenient in ordinary clinical care settings.  We therefore saw need for a quick staging system.  We also lacked a convenient bedside prognostic model to assist patients and families in anticipating important disease milestones and possibly to serve as a comparator in epidemiologic or disease modification studies.

We used PSPRS data gathered from all 273 patients diagnosed from 1995 to 2016 by author LG according to NINDS-SPSP Criteria (Litvan 1996) for possible or probable PSP who made at least 3 visits to our clinic spanning at least 12 months.  We devised multiple convenient candidate staging systems and tested each for correlation with time since symptom onset.  After choosing the best-performing staging system, we used baseline PSPRS and progression velocity in points/month to calculate time to attain each stage and 7 other milestones relating to PSPRS score; advanced scores on PSPRS items relating to dysphagia, dysarthria, gaze palsy and gait difficulty; and death. 

The candidate system with highest r² correlation with time since onset, 0.62, has 5 stages calculated by summing the scores on PSPRS Items #3 (dysphagia for solids by history), #13 (dysphagia for liquids), #26 (gait) and #28 (returning to seat).  This scale correlates closely with total PSPRS (r²= 0.98).  A sum of 1-4=Stage 1, 5-8=Stage 2, 9-12=Stage 3, 13-15=Stage 4 and 16=Stage 5.  Tables showing the prognostic tool will be presented.

This PSP Staging System and the retrospectively validated prognostic tool based on it may prove useful to clinicians, patients and families facing PSP.  Prospective validation is planned.