Menza et al. BMC Public Health 2010, 10:774 http://www.biomedcentral.com/1471-2458/10/774 Table 1 Characteristics of the study population at baselinea (Continued) “No, but I really want to start this month” (Preparation) “No, but I really would like to try in the next 6 months” (Contemplation) “No, and I am really not interested in trying” (Pre-contemplation) Missing Ever been in substance abuse treatment for methamphetamine use Ever attended a support group for methamphetamine use Other substance use, prior 6 weeks Cocaine Crack Inhaled nitrites Erectile dysfunction medications Ecstasy Gamma-hydroxybutyrate Urine testing results Urine positive for methamphetamine Urine positive for cocaine metabolites Urine positive for methamphetamine or cocaine metabolites IQR, interquartile range; UAI, unprotected anal intercourse. aData are n (%) unless otherwise noted. b P < 0.05 Comparing participants at study visits six weeks apart, control participants at the later study visit were less likely to report either weekly or daily methamphetamine use or using >8 quarters of methamphetamine in the prior six weeks than participants at the earlier study visit (aRR = 0.77; 95%CI: 0.68, 0.88 and aRR = 0.69; 95%CI: 0.56, 0.86, respectively); although the frequency and quantity of methamphetamine use declined over time among men in the CM arm, these changes were not as large with respect to frequency (aRR = 0.89; 95% CI: 0.83, 0.96) and not statistically significant with respect to quantity (aRR = 0.93; 95%CI: 0.85, 1.02). CM participants were significantly more likely than control participants to report weekly or daily methamphetamine use and to report using >8 quarters of methampheta- mine at each study visit; these differences were statisti- cally significant during the 12-week follow-up period (Table 4). Accounting for baseline stage of change, control group participants were more likely than CM partici- pants to report being in the action or maintenance stage of change for methamphetamine use during the intervention (74% v. 63%, P = 0.57) and follow-up peri- ods (81% v. 66%, P = 0.18); however, these differences were not statistically significant. In the 6 weeks prior to baseline, 19% of control participants and 14% of CM participants participated in a substance abuse treatment program or peer support group (P = 0.45). After baseline, 26% of control participants and 21% of CM participants reported participating in such inter- ventions (P = 0.38). 14 (11) 14 (11) 6 (5) 20 (16) 32 (25) 52 (41) 35 (28) 53 (42) 59 (46) 39 (31) 19 (15) 25 (20) 44 (35) 31 (24) 65 (51) 11 (16) 9 (13) 3 (4) 10 (14) 17 (24) 25 (36) 17 (24) 26 (37) 35 (50) 26 (37) 8 (11) 16 (23) 28 (40) 12 (17) 35 (50) Page 7 of 13 3 (5) 5 (9) 3 (5) 10 (17) 15 (26) 27 (47) 18 (32) 27 (47) 24 (42) 13 (23) 11 (19) 9 (16) 16 (28) 19 (33) 30 (53) Discussion In this randomized controlled trial of CM, we enrolled 127 non-treatment-seeking MSM over 15 months and successfully collected follow-up data on over 80% of participants. These findings suggest that a randomized controlled trial that specifically seeks to enroll this population is acceptable and feasible. However, less than half of our participants were HIV-negative and restrict- ing enrollment to HIV-negative MSM who use metham- phetamine, the population of interest for a trial using HIV as an outcome, would be challenging. Unlike HIV- negative men, HIV-positive men are often enrolled in ongoing medical care and case management. HIV-posi- tive men may also be more likely to recognize their methamphetamine use as problematic with some attributing their HIV infection to their methampheta- mine use [35]. In addition, the success of peer recruit- ment (over 50% of HIV-negative participants were recruited through peers) over place-based recruitment strategies that have been successful in other HIV pre- vention trials [36] indicates that HIV-negative MSM who use methamphetamine may not share the same social and geographic spaces as HIV-negative men who do not use methamphetamine. HIV-negative men may have also been uncomfortable participating in a trial conducted at an organization well known for its services for HIV-positive individuals. Unfortunately, our findings related to CM are dis- couraging. First, a relatively small proportion of men consistently provided urine specimens for the interven- tion meaning that actual exposure to the intervention