Table 2. Subgroup analysis of body mass index and post-cardiac operation atrial fibrillation.

Items		Number of studies	RR	I2	P
					Within subgroup	Between subgroup
Result of primary analysis		30	1.09 [1.05, 1.12]	82	<0.001	NA
Effect model	Random effect	30	1.04 [1.03, 1.04]	82	<0.001	NA
	Fixed effect	30	1.03 [1.03,1.04]	82	<0.001
Age	≥65	11	1.12 [1.05, 1.20]	78	<0.001	0.15
	<65	15	1.06 [1.02, 1.12]	78	0.002
Region	Northern America	16	1.07 [1.04, 1.10]	84	<0.001	0.25
	Europe	7	1.23 [1.04, 1.45]	75	0.01
	Asia	2	0.95 [0.71, 1.27]	70	0.53
	Oceania	4	1.11[1.06, 1.17]	0	<0.001
NOS scores	<7 scores	7	1.03 [1.00, 1.05]	69	0.05	<0.001
	≥7 scores	20	1.12 [1.08, 1.16]	64	<0.001
Publication year	1999-2010	10	1.12 [1.06, 1.17]	58	<0.001	0.25
	2011-2020	20	1.08[1.04, 1.11]	85	<0.001
AF Diagnosis	ECG	26	1.14 [1.09, 1.19]	67	<0.001	0.33
	Others	4	1.03 [0.97, 1.09]	81	0.37
Sample size	<1000	8	1.20 [0.93, 1.53]	87	0.16	0.37
	≥ 1000	22	1.07 [1.04, 1.09]	75	<0.001
Cases	Case <100	4	1.48 [1.11, 1.99]	33	0.008	0.06
	Case ≥100	26	1.08 [1.05, 1.11]	82	<0.001
Operation type	CABG	17	1.07 [1.03, 1.11]	82	0.001	0.23
	Valve	2	1.34 [0.81, 2.22]	84	0.25
	Mixed	11	1.13 [1.06, 1.19]	78	<0.001
Adjusted factors	Age (+)	26	1.09 [1.05, 1.12]	85	<0.001	0.64
	Age (-)	4	1.33 [0.95, 1.86]	53	<0.001
	Sex (+)	18	1.07 [1.04, 1.11]	86	<0.001	0.28
	Sex (-)	12	1.12 [1.04, 1.21]	65	0.003
	DM (+)	17	1.09 [1.05, 1.13]	86	<0.001	0.89
	DM (-)	13	1.08 [1.02, 1.15]	75	0.01
	Hypertension (+)	14	1.07 [1.04, 1.11]	85	<0.001	0.77
	Hypertension (-)	16	1.09 [1.02, 1.16]	85	<0.001
	COPD (+)	10	1.13 [1.09, 1.17]	33	<0.001	0.14
	COPD (-)	20	1.08 [1.05, 1.12]	83	<0.001
	CAD (+)	10	1.09 [1.03, 1.15]	86	<0.001	0.60
	CAD (-)	17	1.07 [1.03, 1.11]	81	<0.001

Notes.

Abbreviation

NA

not available

ECG

electrocardiograph

CABG

coronary artery bypass grafting

CAD

coronary artery disease

COPD

chronic obstructive pulmonary disease

DM

diabetes mellitus