Table 3.

Subgroup analysis of plasma/serum adiponectin levels in obstructive sleep apnea syndrome cases versus controls.

Subgroup	Variable (N)	SDM	95% CI		Z	p-Value	I2, %	Ph
			Min	Max
Ethnicity	Asian (15)	−0.91	−1.27	−0.56	5.07	<0.00001	84	<0.00001
	Caucasian (13)	−0.63	−0.94	−0.32	4.00	<0.0001	74	<0.00001
	Mixed (8)	−0.41	−0.82	−0.01	2.01	0.04	65	0.006
Country (region)	China (11)	−1.10	−1.54	−0.67	4.98	<0.00001	85	<0.00001
	Turkey (7)	−0.61	−0.81	−0.42	6.09	<0.00001	10	0.35
	USA (5)	−0.15	−0.60	0.30	0.65	0.52	59	0.04
	Brazil (3)	−0.91	−1.33	−0.49	4.27	<0.0001	0	0.93
Adiponectin Source	Serum (23)	−0.85	−1.15	−0.55	5.58	<0.00001	82	<0.00001
	Plasma (13)	−0.47	−0.73	−0.22	3.61	0.0003	64	0.0009
Assay approach	ELISA (25)	−0.69	−0.92	−0.45	5.81	<0.00001	75	<0.00001
	RIA (11)	−0.76	−1.25	−0.28	3.08	0.002	58	<0.00001
Sample size	≥50 (23)	−0.69	−0.94	−0.43	5.24	<0.00001	82	<0.00001
	<50 (13)	−0.77	−1.17	−0.37	3.75	0.0002	74	<0.00001
Publication year	≥2015 (14)	−0.89	−1.25	−0.53	4.83	<0.00001	82	<0.00001
	<2015 (22)	−0.60	−0.87	−0.34	4.43	<0.00001	78	<0.00001
Mean AHI in cases, event/h	≥30 (19)	−0.76	−1.11	−0.41	4.24	<0.0001	84	<0.00001
	15–30 (10)	−0.61	−0.87	−0.34	4.43	<0.00001	61	0.006
	5–15 (5)	−0.42	−0.66	−0.18	3.40	0.0007	30	0.22
Mean BMI, kg/m2	BMI ≥ 30 (15)	−0.52	−0.80	−0.24	3.64	0.0003	75	<0.00001
	BMI < 30 (21)	−0.87	−1.16	−0.57	5.69	<0.00001	81	<0.00001
Mean age, y	Age ≥ 50 (18)	−0.79	−1.06	−0.53	5.86	<0.00001	75	<0.00001
	Age < 50 (18)	−0.64	−0.96	−0.31	3.87	0.0001	81	<0.00001

N, number of studies; SD, standard deviation; BMI, body mass index; AHI, apnea-hypopnea index, P_h, P_{heterogeneity}; ELISA, enzyme linked immunosorbent assay; RIA, radioimmunoassay.