Indicator of whether or not the patient has symptomatic orthostasis as part of Unified Parkinsons Disease Rating Scale (UPDRS).
Fahn S, Elton RL, Members of the UPDRS Development Committee. The Unified Parkinson's Disease Rating Scale. In Fahn S, Marsden CD, Calne DB, Goldstein M, eds: Recent Developments in Parkinson's Disease, Vol. 2. Florham Park, NJ: Macmillan Healthcare Information, 1987. pp. 153 163, 293 304.