Substance use: 4b. Drug use: average number of days using in last 6 months (skewed data)
Study	Intervention	Mean	SD	N
6 months
Drake 1998a	Treatment	42.60	53.50	45
Drake 1998a	Control	45.30	44.30	40
Essock 2006	Treatment	40.80	50.90	75
Essock 2006	Control	44.10	57.70	55
12 months
Drake 1998a	Treatment	26.90	33.40	45
Drake 1998a	Control	47.30	54.50	40
Essock 2006	Treatment	36.80	55.30	76
Essock 2006	Control	36.30	51.70	60
18 months
Drake 1998a	Treatment	41.60	54.90	45
Drake 1998a	Control	34.40	53.30	40
Essock 2006	Treatment	37.70	54.20	78
Essock 2006	Control	39.90	51.70	64
24 months
Drake 1998a	Treatment	35.50	48.00	45
Drake 1998a	Control	37.00	48.80	40
Essock 2006	Treatment	28.20	47.20	69
Essock 2006	Control	39.10	56.20	66
30 months
Drake 1998a	Treatment	33.90	50.00	45
Drake 1998a	Control	46.40	53.10	40
Essock 2006	Treatment	35.00	51.30	73
Essock 2006	Control	35.90	54.50	60
36 months
Drake 1998a	Treatment	38.20	54.70	45
Drake 1998a	Control	51.50	67.20	40
Essock 2006	Treatment	31.70	47.80	71
Essock 2006	Control	32.10	49.00	60