Table 1.

Characteristics of the studies included in the meta-analysis.

Author	Date	Country	Type	BMI ≥ 30		25 ≤ BMI < 30		BMI < 25
				Number of PD	Number of observation objects	Number of PD	Number of observation objects	Number of PD	Number of observation objects
Morales-Briceno et al. [18]	2012	Mexico	Case-control	34	102	83	156	60	96
Ragonese et al. [21]	2008	Italy	Case-control	101	208	104	212	107	205
Savica et al. [22]	2012	USA	Case-control	52	95	87	173	57	124
Hu et al. [23]	2006	Finland	Cohort study	112	122292	255	333535	159	405402
Palacios et al. [19]	2011	USA	Cohort study	79	255341	286	693150	274	772443
Chen et al. [17]	2004	USA	Cohort study	31	246927	158	768691	262	2065803
Driver et al. [20]	2008	USA	Cohort study	20	919	216	8344	320	12578

BMI indicates body mass index (kg/m²); PD indicates Parkinson's disease.