Responsiveness - slopes of change (mean ± SD) of the NNIPPS-PPS scores by Strata.

PSP and MSA columns: NNIPPS-PPS dimensional and total scores slopes of change (mean ± SD points per year) by strata; N: number of patients with at least two usable assessments over the three year follow-up. Maximum (most severe) theoretical scores are indicated in the far left column (brackets).Strata p value column: p value from ANOVA comparing slope of change between strata.Slope test columns: p value from within-group t test comparing slopes of change within strata (PSP, MSA) to 0 (no change).*Total score-2:Cerebellar and Orthostatic scores at follow-up visits were found to be highly biased by interference with walking ability (some items becoming impossible to rate when the patient was unable to stand), and/or motor disability (eg, rigidity), their respective scorings were removed from this Total score calculation with minor alteration in the overall PPS slope of change in both groups.