Table 2.

Subgroup analysis of the source of heterogeneity in meta-analysis of randomized controlled trials comparing efficacy of music therapy with inactive control groups.

Characteristics	Number of studies	Sample size		Heterogeneity [I2], % (P)	Standardized Mean Difference (95%CI)	Q	P
		Experimental group	Control group
Participants
Medically ill patients	4	143	141	96.1(<0.001)	−2.04(−3.11,−0.96)
Psychiatric patients	2	29	31	76.2(0.040)	−1.26(−2.70,0.18)
Veterans	1	25	15	Not applicable	−0.70(−1.36,−0.04)	4.37	0.113
Sample
Males + females	4	113	102	85.1(<0.001)	−1.84(−2.82,−0.85)
Females only	3	84	85	93.8(<0.001)	−1.39(−2.83,0.06)	0.26	0.612
Mean age
< 40 years	4	111	109	86.5(<0.001)	−1.83(−2.83,−0.83)
> 40 years	3	86	78	93.6(<0.001)	−1.40(−2.84,0.04)	0.23	0.630
Diagnostic criteria of PTSD
DSM	2	35	35	28.7(0.240)	−2.78(−3.46,−2.10)
DSM + ICD	1	21	23	Not applicable	−0.63(−1.24,−0.02)
Not reported	3	116	114	91.8(<0.001)	−1.72(−2.95,−0.50)
ICD	1	25	15	Not applicable	−0.70(−1.36,−0.04)	18.60	<0.001
Music therapy
Led by music therapists	4	81	73	89.1(<0.001)	−1.58(−2.75,−0.40)
Music listening only	3	116	114	91.8(<0.001)	−1.72(−2.95,−0.50)	0.030	0.866
Treatment duration
2–4 months	3	75	75	0.0(0.49)	−2.83(−3.29,−2.36)
<2 months	4	122	112	73.6(0.038)	−0.95(−1.47,−0.42)	27.79	<0.001
Treatment frequency
Daily	3	116	114	92.3(<0.001)	−1.72(−2.95,−0.50)
Weekly or biweekly	4	81	73	89.1(<0.001)	−1.58(−2.75,−0.40)	0.030	0.866
Intervention of the control group
Care as usual alone	4	143	141	91.1(<0.001)	−2.04(−3.11,−0.96)
Waitlist + care as usual	3	54	46	54.7(0.110)	−0.95(−1.63,−0.26)	2.79	0.095

Note: DSM, Diagnostic & Statistical Manual of Mental Disorders; ICD, International Classification of Diseases; NR, not reported