Table 1.

Prevalence of drooling in Parkinson's disease

Year	Reference	Screening tools	Number surveyed	Prevalence (%)
2012	Damian et al. [16]	SCOPA-AUT	62	81
2012	Ozdilek et al. [15]	UPDRS part II: salivation subscore	50	84
2012	Rana et al. [14]	UPDRS part II: salivation subscore	307	40
2012	Perez-Lloret et al. [13]	UPDRS part II: salivation subscore	419	37
2011	Müller et al. [12]	UPDRS part II: salivation subscore	207	42
2010	Leibner et al. [11]	Questionnaire: 7-item drooling survey questionnaire	58	59
2008	Cheon et al. [10]	PD-NMSQuest	74	32
2008	Nicaretta et al. [9]	UPDRS part II: salivation subscore	134	10
2007	Martinez-Martin et al. [8]	PD-NMSQuest	525	42
2007	Verbaan et al. [7]	SCOPA-AUT	420	73
2007	Kalf et al. [6]	Questionnaire: “Do you suffer from involuntary loss of saliva (drooling)?”	216	49
2002	Siddiqui et al. [5]	Questionnaire: rating 0-4 point for detecting severity of symptoms 0 = normal 1 = rare (one per month) 2 = occasional (one per week) 3 = frequent (one per day) 4 = constant.	44	52
2002	Volonté et al. [4]	Questionnaire: Present or absent nocturnal sialorrhea	65	15
2000	Scott et al. [3]	Questionnaire: present or absent drooling	943	40
1991	Edwards et al. [2]	Questionnaire: rating 0-4 point for detecting severity of symptoms 0 = normal 1 = rare (one per month) 2 = occasional (one per week) 3 = frequent (one per day) 4 = constant.	96	70

UPDRS: Unified Parkinson's Disease Rating Scale; SCOPA-AUT: Scales for Outcome in Parkinson's disease; autonomic; PD-NMSQuest: Parkinson's disease non-motor symptoms questionnaire