Table 3.

DHEA-S subgroup analysis.

	Number of studies	SMD (95% CI)	Z	P-value	Heterogeneity
					Q statistic (DF; p-value)	τ2	I2
All	28	−0.69 [−1.17; −0.22]	−2.84	0.004	570.78 27 < 0.0001	1.49	95.30%
MATERIAL
Plasma	11	−0.66 [−1.53; 0.21]	−1.49	0.136	185.75 10 < 0.0001	2.01	95.90%
Serum	17	−0.71 [−1.32; −0.11]	−2.31	0.021	376.20 16 < 0.0001	1.45	95.70%
STUDY COUNTRY
Italy	7	−1.85 [−3.01; −0.69]	−3.12	0.002	150.94 6 < 0.0001	2.30	96.00%
Not Italy	21	−0.30 [−0.87; 0.27]	−1.05	0.296	411.53 20 < 0.0001	1.60	95.10%
NOS
High	3	−0.12 [−0.47; 0.22]	−0.69	0.490	4.39 2 0.1116	0.05	54.40%
Medium	25	−0.74 [−1.32; −0.16]	−2.49	0.013	537.97 24 < 0.0001	2.02	95.50%
AD ASSESSMENT
NINCDS-ARDRA	18	−0.68 [−1.27; −0.09]	−2.24	0.025	402.64 17 < 0.0001	1.48	95.80%
Other	10	−0.72 [−1.63; 0.20]	−1.54	0.125	166.36 9 < 0.0001	2.02	94.60%
ASSAYED METHODS
RIA	17	−0.97 [−1.59; −0.35]	−3.06	0.002	333.42 16 < 0.0001	1.54	95.20%
Other	11	−0.23 [−1.14; 0.68]	−0.50	0.620	237.34 10 < 0.0001	2.16	95.80%
SEVERITY OF AD
Mild	4	−0.33 [−1.98; 1.33]	−0.39	0.699	80.50 3 < 0.0001	2.72	96.30%
Moderate	17	−1.12 [−1.71; −0.53]	−3.72	0.002	361.47 16 < 0.0001	1.38	95.60%
Severe	7	0.23 [−1.07; 1.53]	0.35	0.729	123.91 6 < 0.0001	2.84	95.20%

USA, United States of America; RIA, radioimmunoassay; SMD, standardized mean difference; DF, degrees of Freedom; DSM, Diagnostic, and Statistical Manual of Mental Disorders; AD, Alzheimer's disease.