Contingency management to reduce methamphetamine use and sexual risk among men who have sex with men: a randomized controlled trial

Table 4 Effect of a contingency management intervention on detection of methamphetamine use by rapid urine screen and on self-reported frequency and quantity of methamphetamine use in the prior 6 weeks

	Positive methamphetamine urinalysis, n (%)
Visit	Total	Contingency Management	Control	Unadjusted RR (95% CI)	Adjusted RR^a(95% CI)
Baseline	44/127 (35)	28/70 (40)	16/57 (28)
Week 6	27/92 (29)	17/48 (35)	10/44 (23)
Week 12	33/100 (33)	20/55 (36)	13/45 (29)	1.39 (0.81, 2.38)	1.09 (0.76, 1.57)
Week 18	39/97 (40)	24/52 (46)	15/45 (33)
Week 24	39/105 (37)	29/58 (50)	10/47 (21)	1.77 (1.13, 2.78)	1.21 (0.95, 1.54)
	Self-reported weekly or more frequent methamphetamine use, n (%)
Visit	Total	Contingency Management	Control	Unadjusted RR (95% CI)	Adjusted RR^b (95% CI)
Baseline	83/127 (65)	51/70 (73)	32/57 (56)
Week 6	32/92 (35)	20/48 (42)	12/44 (27)
Week 12	39/102 (38)	25/56 (45)	14/46 (30)	1.50 (0.93, 2.42)	1.29 (0.82, 2.04)
Week 18	37/99 (37)	26/53 (49)	11/46 (24)
Week 24	40/107 (37)	29/60 (48)	11/47 (23)	2.06 (1.29, 3.29)	1.76 (1.13, 2.73)
	Self-reported use of more than eight quarters of methamphetamine, n (%)
Visit	Total	Contingency Management	Control	Unadjusted RR (95% CI)	Adjusted RR^c (95% CI)
Baseline	59/127 (46)	37/70 (53)	22/57 (39)
Week 6	22/91 (24)	14/47 (29)	8/44 (18)
Week 12	28/99 (28)	21/55 (37)	7/44 (16)	2.01 (1.09, 3.73)	1.80 (0.95, 3.40)
Week 18	23/97 (24)	19/52 (36)	4/45 (9)
Week 24	30/105 (29)	24/59 (40)	6/46 (13)	3.52 (1.70, 7.30)	3.02 (1.47, 6.23)

CI, confidence interval; RR, relative risk; one quarter of methamphetamine is equivalent to 0.25 grams. Statistically significant results (P < 0.05) are bolded.
^aAdjusted for methamphetamine urinalysis result at baseline and stage of change for methamphetamine use at baseline (maintenance, action, preparation, contemplation, pre-contemplation, missing).
^bAdjusted for baseline self-reported weekly or more frequent use of methamphetamine in the prior 6 weeks.
^cAdjusted for baseline self-reported use of more than eight quarters of methamphetamine in the prior 6 weeks.

ISSN: 1471-2458