Reduced Risk of Parkinson’s Disease in Users of Calcium Channel Blockers: A Meta-Analysis

Table 2

Characteristics of case-control studies included in meta-analysis.

Author, year (country)^a	Period of recruitment	Source of study population	Study size	Number of PD patients	Assessment of CCB usage	Assessment of PD	Quality rating (NOC)
Ritz et al. [18] 2010 (Denmark)	2001–2006	Population based	11,582	1,931	National pharmacy database	Hospital register	8^c
Becker et al. [19] 2008 (UK)	1994–2005	Population based	7,274	3,637	General practice research database	General practice research database	8^c
Ton et al. [20] 2007 (USA)	1992–2002	Population based	556	191	Medical records	Medical records and cardinal signs	9^b

Country of study conducted.
^bHigh quality.
^cMedium quality.
UK: United Kingdom, USA: United States of America, CCB: calcium channel blockers, PD: Parkinson’s disease, and NOC: Newcastle-Ottawa Scale.