Additionally, there was a positive association between triadic concurrency and UAI: triads were more likely to involve UAI with both partners if they were concurrent (unadj. OR [95% CI] = 1.93 [1.75, 2.14], adj. OR = 1.57 [1.41 1.75]). This association was consistent across levels of by participant race/ethnicity (adjusted p = 0.95). Individual and triadic level concurrency results are also provided stratified by categories of participant age in Supplementary Digital Content Tables 1 and 2.