Unified Parkinson Disease Rating Scale Calculator

Part III of the Unified Parkinson Disease Rating Scale is the examiner-administered motor section. Each item is rated 0 for normal, 1 slight, 2 mild, 3 moderate, and 4 severe, and the items are simply summed, which treats an ordinal set of anchors as if it were an interval measure. The tasks are chosen to isolate the cardinal parkinsonian signs: passive range-of-motion testing of the neck and four limbs for lead-pipe or cogwheel rigidity, repetitive finger tapping, hand opening and closing, pronation-supination, toe tapping and leg agility for bradykinesia, and separate ratings of rest, postural, and kinetic tremor. The bradykinesia items are graded not only on speed but on decrement, the progressive loss of amplitude over about ten repetitions that separates parkinsonian slowness from spasticity or depression. Subscores matter clinically. A high tremor score with a low axial score suggests the tremor-dominant phenotype, which progresses more slowly than the postural instability and gait difficulty phenotype, and marked asymmetry supports idiopathic Parkinson disease over multiple system atrophy or progressive supranuclear palsy. Most untreated early-stage patients score roughly 10 to 30 points, and a change of about 3 points is generally taken as the minimal clinically important difference. The main caveats are inter-rater variability at adjacent anchors, the strong dependence of the total on medication timing, and the fact that postural stability rests on a single pull test that is difficult to standardize.

Before the UPDRS existed, clinicians used a scatter of incompatible instruments: the staging system published by Margaret Hoehn and Melvin Yahr in Neurology in 1967, the Schwab and England activities of daily living percentage, the Webster rating scale of 1968, the Columbia University Rating Scale, and the Northwestern University Disability Scale. Results from different centers could not be pooled because they were not measuring the same thing. In the mid-1980s a committee including Stanley Fahn and C. David Marsden merged the more useful features of these scales into a single four-part instrument, published in 1987 in the volume Recent Developments in Parkinson's Disease. The UPDRS then served as the default outcome measure for essentially every Parkinson drug trial for two decades. A Movement Disorder Society task force reviewed it in 2003 and concluded that although its clinimetric properties were broadly sound, several items had ambiguous or missing anchor descriptions, non-motor symptoms were underrepresented, and no officially validated translations existed. The society commissioned a revision led by Christopher Goetz, and the MDS-UPDRS appeared in Movement Disorders in 2008. Its Part III expands to 18 items yielding 33 scores and a maximum of 132 points, with explicit wording for every rating level. The older version remains in use because so much historical trial data is expressed in its units.