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Table 4 presents the results from multilevel analysis examining the effects of intervention (couple and individual risk reduction jointly vs. couple wellness promotion) and the effects of modality (couple risk reduction vs. individual risk reduction) with respect to the sexual risk behavior outcomes after adjusting for the baseline measures of the outcomes and gender. The results indicate that, over the entire follow-up period, there was a 30% reduction in the incidence rate of unprotected acts of intercourse with their study partners for the participants in the 2 risk-reduction intervention conditions compared with the participants in the couple wellness promotion condition (IRR = 0 70; 95% CI = 0 53 to 0 92) and a 29% reduction when comparing couple risk reduction with Individual Risk Reduction (IRR = 0 71; 95% CI = 0 51, 0 97). These intervention effects were significant at IPT (IRR = 0 58; 95% CI = 0 38, 0 88) and 6-month follow-up (IRR = 0 70; 95% CI = 0 54, 0 92) but not at 12-month follow-up (IRR = 0 85; 95% CI = 0 55, 1 32). Although the modality effect was not significant at IPT (IRR = 0 84; 95% CI = 0 52, 1 35), participants in the Couple Risk Reduction condition experienced a 30% reduction of unprotected acts of intercourse at 6-month follow-up (IRR = 0 70; 95% CI = 0 51, 0 96) and a 41% reduction at 12-month follow-up (IRR = 0 59; 95% CI = 0 35 to 0 99) compared with iIndividual risk reduction participants.

We also examined effects of the intervention and modality on injecting drug use in the past 90 days among the total sample.

OR

Table 3 presents results from random-effects generalized linear models examining the effects of the intervention (multimedia and traditional WORTH jointly vs. Wellness Promotion) with respect to sexual behavior outcomes. Over the 12-month follow-up period, there was a 28% reduction in the number of unprotected sex acts with primary partners for participants in multimedia and traditional WORTH when compared with participants in the Wellness Promotion condition (IRR = 0.72; 95% CI = 0.57–0.90). These intervention effects were significant at three- (IRR=0.62; 95% CI=0.45–0.86) and six-month follow-up (IRR=0.70; 95% CI=0.55–0.88) but not at the 12-month follow-up assessment (IRR = 0.87; 95% CI = 0.59–1.26). Women assigned to one of the two WORTH conditions reported on average a 10% higher proportion of protected sex acts with their primary partners than women in the control condition over the entire follow-up period (b=0.10; 95% CI=0.02–0.18). Significant effects for proportion of protected sex acts were found at three- (b = 0.14; 95% CI=0.04–0.24) and six-month follow-up assessments (b=0.11; 95% CI=0.03–0.19). Women assigned to the two intervention conditions were more likely to report consistent condom use during sex with their primary partners than women assigned to Wellness Promotion over the 12-month follow-up period (OR = 2.36; 95% CI = 1.28–4.37) and at three- (OR = 3.42; 95% CI = 1.61–7.27) and six-month follow-up assessments (OR = 2.61; 95% CI = 1.38–4.95). Similar intervention effects were also found in the reports of sexual behavior outcomes with all partners.

OR

Table 3 also presents the effects of modality, comparing multimedia and traditional WORTH with respect to sexual behavior outcomes. We did not find significant modality effects in any of the sexual behavior endpoints. In order to identify whether one or both intervention conditions were more efficacious than the control condition, additional analyses were performed to examine the effects of the two intervention conditions separately (i.e. multimedia WORTH vs. Wellness Promotion and traditional WORTH vs. Wellness Promotion). Dummy coding, which set Wellness Promotion as the reference condition, was used in the random-effect models to examine the respective effects of multimedia and traditional WORTH on sexual risk behaviors. The results (not represented in Table 3) confirmed that both intervention conditions had significant effects in lowering the number of unprotected sex acts (e.g. with the primary partner over the entire follow-up period, IRR = 0.72 and 95% CI = 0.55–0.93 for multimedia WORTH; IRR=0.72 and 95% CI=0.55–0.95

for traditional WORTH), increasing the proportion of protected sex acts (e.g., with the primary partner over the entire follow-up period, b = 0.11 and 95% CI = 0.02–0.20 for multimedia WORTH; b = 0.10 and 95% CI = 0.01–0.19 for traditional WORTH), and increasing consistent condom use (e.g., with the primary partner over the entire follow-up period, OR = 2.38 and 95% CI=1.16–4.87 for multimedia WORTH; OR=2.34 and 95% CI = 1.16–4.75 for traditional WORTH compared with the control condition).